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It's been a relatively busy cycle for docs: 

- A fair pile of RST conversions, many from Mauro.  These create more
    than the usual number of simple but annoying merge conflicts with other
    trees, unfortunately.  He has a lot more of these waiting on the wings
    that, I think, will go to you directly later on.
 
  - A new document on how to use merges and rebases in kernel repos, and one
    on Spectre vulnerabilities.
 
  - Various improvements to the build system, including automatic markup of
    function() references because some people, for reasons I will never
    understand, were of the opinion that :c:func:``function()`` is
    unattractive and not fun to type.
 
  - We now recommend using sphinx 1.7, but still support back to 1.4.
 
  - Lots of smaller improvements, warning fixes, typo fixes, etc.
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Merge tag 'docs-5.3' of git://git.lwn.net/linux

Pull Documentation updates from Jonathan Corbet:
 "It's been a relatively busy cycle for docs:

   - A fair pile of RST conversions, many from Mauro. These create more
     than the usual number of simple but annoying merge conflicts with
     other trees, unfortunately. He has a lot more of these waiting on
     the wings that, I think, will go to you directly later on.

   - A new document on how to use merges and rebases in kernel repos,
     and one on Spectre vulnerabilities.

   - Various improvements to the build system, including automatic
     markup of function() references because some people, for reasons I
     will never understand, were of the opinion that
     :c:func:``function()`` is unattractive and not fun to type.

   - We now recommend using sphinx 1.7, but still support back to 1.4.

   - Lots of smaller improvements, warning fixes, typo fixes, etc"

* tag 'docs-5.3' of git://git.lwn.net/linux: (129 commits)
  docs: automarkup.py: ignore exceptions when seeking for xrefs
  docs: Move binderfs to admin-guide
  Disable Sphinx SmartyPants in HTML output
  doc: RCU callback locks need only _bh, not necessarily _irq
  docs: format kernel-parameters -- as code
  Doc : doc-guide : Fix a typo
  platform: x86: get rid of a non-existent document
  Add the RCU docs to the core-api manual
  Documentation: RCU: Add TOC tree hooks
  Documentation: RCU: Rename txt files to rst
  Documentation: RCU: Convert RCU UP systems to reST
  Documentation: RCU: Convert RCU linked list to reST
  Documentation: RCU: Convert RCU basic concepts to reST
  docs: filesystems: Remove uneeded .rst extension on toctables
  scripts/sphinx-pre-install: fix out-of-tree build
  docs: zh_CN: submitting-drivers.rst: Remove a duplicated Documentation/
  Documentation: PGP: update for newer HW devices
  Documentation: Add section about CPU vulnerabilities for Spectre
  Documentation: platform: Delete x86-laptop-drivers.txt
  docs: Note that :c:func: should no longer be used
  ...
This commit is contained in:
Linus Torvalds 2019-07-09 12:34:26 -07:00
parent 7011b7e1b7 454f96f2b7
commit e9a83bd232
416 changed files with 12093 additions and 8515 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
Documentation/ABI/testing/sysfs-devices-system-cpu
View File

@ -137,7 +137,8 @@ Description: Discover cpuidle policy and mechanism
current_governor: (RW) displays current idle policy. Users can current_governor: (RW) displays current idle policy. Users can
switch the governor at runtime by writing to this file. switch the governor at runtime by writing to this file.
See files in Documentation/cpuidle/ for more information. See Documentation/admin-guide/pm/cpuidle.rst and
Documentation/driver-api/pm/cpuidle.rst for more information.
What: /sys/devices/system/cpu/cpuX/cpuidle/stateN/name What: /sys/devices/system/cpu/cpuX/cpuidle/stateN/name

2
Documentation/ABI/testing/sysfs-kernel-uids
View File

@ -11,4 +11,4 @@ Description:
example would be, if User A has shares = 1024 and user example would be, if User A has shares = 1024 and user
B has shares = 2048, User B will get twice the CPU B has shares = 2048, User B will get twice the CPU
bandwidth user A will. For more details refer bandwidth user A will. For more details refer
Documentation/scheduler/sched-design-CFS.txt Documentation/scheduler/sched-design-CFS.rst

2
Documentation/DMA-API.txt
View File

@ -198,7 +198,7 @@ call to set the mask to the value returned.
:: ::
size_t size_t
dma_direct_max_mapping_size(struct device *dev); dma_max_mapping_size(struct device *dev);
Returns the maximum size of a mapping for the device. The size parameter Returns the maximum size of a mapping for the device. The size parameter
of the mapping functions like dma_map_single(), dma_map_page() and of the mapping functions like dma_map_single(), dma_map_page() and

31
Documentation/EDID/HOWTO.txt → Documentation/EDID/howto.rst
View File

@ -1,3 +1,9 @@
:orphan:
====
EDID
====
In the good old days when graphics parameters were configured explicitly In the good old days when graphics parameters were configured explicitly
in a file called xorg.conf, even broken hardware could be managed. in a file called xorg.conf, even broken hardware could be managed.
@ -34,16 +40,19 @@ Makefile. Please note that the EDID data structure expects the timing
values in a different way as compared to the standard X11 format. values in a different way as compared to the standard X11 format.
X11: X11:
HTimings: hdisp hsyncstart hsyncend htotal HTimings:
VTimings: vdisp vsyncstart vsyncend vtotal hdisp hsyncstart hsyncend htotal
VTimings:
vdisp vsyncstart vsyncend vtotal
EDID: EDID::
#define XPIX hdisp
#define XBLANK htotal-hdisp
#define XOFFSET hsyncstart-hdisp
#define XPULSE hsyncend-hsyncstart
#define YPIX vdisp #define XPIX hdisp
#define YBLANK vtotal-vdisp #define XBLANK htotal-hdisp
#define YOFFSET vsyncstart-vdisp #define XOFFSET hsyncstart-hdisp
#define YPULSE vsyncend-vsyncstart #define XPULSE hsyncend-hsyncstart
#define YPIX vdisp
#define YBLANK vtotal-vdisp
#define YOFFSET vsyncstart-vdisp
#define YPULSE vsyncend-vsyncstart

13
Documentation/Kconfig Normal file
View File

@ -0,0 +1,13 @@
config WARN_MISSING_DOCUMENTS
bool "Warn if there's a missing documentation file"
depends on COMPILE_TEST
help
It is not uncommon that a document gets renamed.
This option makes the Kernel to check for missing dependencies,
warning when something is missing. Works only if the Kernel
is built from a git tree.
If unsure, select 'N'.

14
Documentation/Makefile
View File

@ -4,6 +4,11 @@
subdir-y := devicetree/bindings/ subdir-y := devicetree/bindings/
# Check for broken documentation file references
ifeq ($(CONFIG_WARN_MISSING_DOCUMENTS),y)
$(shell $(srctree)/scripts/documentation-file-ref-check --warn)
endif
# You can set these variables from the command line. # You can set these variables from the command line.
SPHINXBUILD = sphinx-build SPHINXBUILD = sphinx-build
SPHINXOPTS = SPHINXOPTS =
@ -23,11 +28,13 @@ ifeq ($(HAVE_SPHINX),0)
.DEFAULT: .DEFAULT:
$(warning The '$(SPHINXBUILD)' command was not found. Make sure you have Sphinx installed and in PATH, or set the SPHINXBUILD make variable to point to the full path of the '$(SPHINXBUILD)' executable.) $(warning The '$(SPHINXBUILD)' command was not found. Make sure you have Sphinx installed and in PATH, or set the SPHINXBUILD make variable to point to the full path of the '$(SPHINXBUILD)' executable.)
@echo @echo
@./scripts/sphinx-pre-install @$(srctree)/scripts/sphinx-pre-install
@echo " SKIP Sphinx $@ target." @echo " SKIP Sphinx $@ target."
else # HAVE_SPHINX else # HAVE_SPHINX
export SPHINXOPTS = $(shell perl -e 'open IN,"sphinx-build --version 2>&1 |"; while (<IN>) { if (m/([\d\.]+)/) { print "-jauto" if ($$1 >= "1.7") } ;} close IN')
# User-friendly check for pdflatex and latexmk # User-friendly check for pdflatex and latexmk
HAVE_PDFLATEX := $(shell if which $(PDFLATEX) >/dev/null 2>&1; then echo 1; else echo 0; fi) HAVE_PDFLATEX := $(shell if which $(PDFLATEX) >/dev/null 2>&1; then echo 1; else echo 0; fi)
HAVE_LATEXMK := $(shell if which latexmk >/dev/null 2>&1; then echo 1; else echo 0; fi) HAVE_LATEXMK := $(shell if which latexmk >/dev/null 2>&1; then echo 1; else echo 0; fi)
@ -70,12 +77,14 @@ quiet_cmd_sphinx = SPHINX $@ --> file://$(abspath $(BUILDDIR)/$3/$4)
$(abspath $(BUILDDIR)/$3/$4) $(abspath $(BUILDDIR)/$3/$4)
htmldocs: htmldocs:
@$(srctree)/scripts/sphinx-pre-install --version-check
@+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,html,$(var),,$(var))) @+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,html,$(var),,$(var)))
linkcheckdocs: linkcheckdocs:
@$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,linkcheck,$(var),,$(var))) @$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,linkcheck,$(var),,$(var)))
latexdocs: latexdocs:
@$(srctree)/scripts/sphinx-pre-install --version-check
@+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,latex,$(var),latex,$(var))) @+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,latex,$(var),latex,$(var)))
ifeq ($(HAVE_PDFLATEX),0) ifeq ($(HAVE_PDFLATEX),0)
@ -87,14 +96,17 @@ pdfdocs:
else # HAVE_PDFLATEX else # HAVE_PDFLATEX
pdfdocs: latexdocs pdfdocs: latexdocs
@$(srctree)/scripts/sphinx-pre-install --version-check
$(foreach var,$(SPHINXDIRS), $(MAKE) PDFLATEX="$(PDFLATEX)" LATEXOPTS="$(LATEXOPTS)" -C $(BUILDDIR)/$(var)/latex || exit;) $(foreach var,$(SPHINXDIRS), $(MAKE) PDFLATEX="$(PDFLATEX)" LATEXOPTS="$(LATEXOPTS)" -C $(BUILDDIR)/$(var)/latex || exit;)
endif # HAVE_PDFLATEX endif # HAVE_PDFLATEX
epubdocs: epubdocs:
@$(srctree)/scripts/sphinx-pre-install --version-check
@+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,epub,$(var),epub,$(var))) @+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,epub,$(var),epub,$(var)))
xmldocs: xmldocs:
@$(srctree)/scripts/sphinx-pre-install --version-check
@+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,xml,$(var),xml,$(var))) @+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,xml,$(var),xml,$(var)))
endif # HAVE_SPHINX endif # HAVE_SPHINX

50
Documentation/RCU/UP.txt → Documentation/RCU/UP.rst
View File

@ -1,17 +1,19 @@
RCU on Uniprocessor Systems .. _up_doc:
RCU on Uniprocessor Systems
===========================
A common misconception is that, on UP systems, the call_rcu() primitive A common misconception is that, on UP systems, the call_rcu() primitive
may immediately invoke its function. The basis of this misconception may immediately invoke its function. The basis of this misconception
is that since there is only one CPU, it should not be necessary to is that since there is only one CPU, it should not be necessary to
wait for anything else to get done, since there are no other CPUs for wait for anything else to get done, since there are no other CPUs for
anything else to be happening on. Although this approach will -sort- -of- anything else to be happening on. Although this approach will *sort of*
work a surprising amount of the time, it is a very bad idea in general. work a surprising amount of the time, it is a very bad idea in general.
This document presents three examples that demonstrate exactly how bad This document presents three examples that demonstrate exactly how bad
an idea this is. an idea this is.
Example 1: softirq Suicide Example 1: softirq Suicide
--------------------------
Suppose that an RCU-based algorithm scans a linked list containing Suppose that an RCU-based algorithm scans a linked list containing
elements A, B, and C in process context, and can delete elements from elements A, B, and C in process context, and can delete elements from
@ -28,8 +30,8 @@ your kernel.
This same problem can occur if call_rcu() is invoked from a hardware This same problem can occur if call_rcu() is invoked from a hardware
interrupt handler. interrupt handler.
Example 2: Function-Call Fatality Example 2: Function-Call Fatality
---------------------------------
Of course, one could avert the suicide described in the preceding example Of course, one could avert the suicide described in the preceding example
by having call_rcu() directly invoke its arguments only if it was called by having call_rcu() directly invoke its arguments only if it was called
@ -46,11 +48,13 @@ its arguments would cause it to fail to make the fundamental guarantee
underlying RCU, namely that call_rcu() defers invoking its arguments until underlying RCU, namely that call_rcu() defers invoking its arguments until
all RCU read-side critical sections currently executing have completed. all RCU read-side critical sections currently executing have completed.
Quick Quiz #1: why is it -not- legal to invoke synchronize_rcu() in Quick Quiz #1:
this case? Why is it *not* legal to invoke synchronize_rcu() in this case?
:ref:`Answers to Quick Quiz <answer_quick_quiz_up>`
Example 3: Death by Deadlock Example 3: Death by Deadlock
----------------------------
Suppose that call_rcu() is invoked while holding a lock, and that the Suppose that call_rcu() is invoked while holding a lock, and that the
callback function must acquire this same lock. In this case, if callback function must acquire this same lock. In this case, if
@ -76,25 +80,30 @@ there are cases where this can be quite ugly:
If call_rcu() directly invokes the callback, painful locking restrictions If call_rcu() directly invokes the callback, painful locking restrictions
or API changes would be required. or API changes would be required.
Quick Quiz #2: What locking restriction must RCU callbacks respect? Quick Quiz #2:
What locking restriction must RCU callbacks respect?
:ref:`Answers to Quick Quiz <answer_quick_quiz_up>`
Summary Summary
-------
Permitting call_rcu() to immediately invoke its arguments breaks RCU, Permitting call_rcu() to immediately invoke its arguments breaks RCU,
even on a UP system. So do not do it! Even on a UP system, the RCU even on a UP system. So do not do it! Even on a UP system, the RCU
infrastructure -must- respect grace periods, and -must- invoke callbacks infrastructure *must* respect grace periods, and *must* invoke callbacks
from a known environment in which no locks are held. from a known environment in which no locks are held.
Note that it -is- safe for synchronize_rcu() to return immediately on Note that it *is* safe for synchronize_rcu() to return immediately on
UP systems, including !PREEMPT SMP builds running on UP systems. UP systems, including PREEMPT SMP builds running on UP systems.
Quick Quiz #3: Why can't synchronize_rcu() return immediately on Quick Quiz #3:
UP systems running preemptable RCU? Why can't synchronize_rcu() return immediately on UP systems running
preemptable RCU?
.. _answer_quick_quiz_up:
Answer to Quick Quiz #1: Answer to Quick Quiz #1:
Why is it -not- legal to invoke synchronize_rcu() in this case? Why is it *not* legal to invoke synchronize_rcu() in this case?
Because the calling function is scanning an RCU-protected linked Because the calling function is scanning an RCU-protected linked
list, and is therefore within an RCU read-side critical section. list, and is therefore within an RCU read-side critical section.
@ -104,12 +113,13 @@ Answer to Quick Quiz #1:
Answer to Quick Quiz #2: Answer to Quick Quiz #2:
What locking restriction must RCU callbacks respect? What locking restriction must RCU callbacks respect?
Any lock that is acquired within an RCU callback must be Any lock that is acquired within an RCU callback must be acquired
acquired elsewhere using an _irq variant of the spinlock elsewhere using an _bh variant of the spinlock primitive.
primitive. For example, if "mylock" is acquired by an For example, if "mylock" is acquired by an RCU callback, then
RCU callback, then a process-context acquisition of this a process-context acquisition of this lock must use something
lock must use something like spin_lock_irqsave() to like spin_lock_bh() to acquire the lock. Please note that
acquire the lock. it is also OK to use _irq variants of spinlocks, for example,
spin_lock_irqsave().
If the process-context code were to simply use spin_lock(), If the process-context code were to simply use spin_lock(),
then, since RCU callbacks can be invoked from softirq context, then, since RCU callbacks can be invoked from softirq context,
@ -119,7 +129,7 @@ Answer to Quick Quiz #2:
This restriction might seem gratuitous, since very few RCU This restriction might seem gratuitous, since very few RCU
callbacks acquire locks directly. However, a great many RCU callbacks acquire locks directly. However, a great many RCU
callbacks do acquire locks -indirectly-, for example, via callbacks do acquire locks *indirectly*, for example, via
the kfree() primitive. the kfree() primitive.
Answer to Quick Quiz #3: Answer to Quick Quiz #3:

19
Documentation/RCU/index.rst Normal file
View File

@ -0,0 +1,19 @@
.. _rcu_concepts:
============
RCU concepts
============
.. toctree::
:maxdepth: 1
rcu
listRCU
UP
.. only:: subproject and html
Indices
=======
* :ref:`genindex`

38
Documentation/RCU/listRCU.txt → Documentation/RCU/listRCU.rst
View File

@ -1,5 +1,7 @@
Using RCU to Protect Read-Mostly Linked Lists .. _list_rcu_doc:
Using RCU to Protect Read-Mostly Linked Lists
=============================================
One of the best applications of RCU is to protect read-mostly linked lists One of the best applications of RCU is to protect read-mostly linked lists
("struct list_head" in list.h). One big advantage of this approach ("struct list_head" in list.h). One big advantage of this approach
@ -7,8 +9,8 @@ is that all of the required memory barriers are included for you in
the list macros. This document describes several applications of RCU, the list macros. This document describes several applications of RCU,
with the best fits first. with the best fits first.
Example 1: Read-Side Action Taken Outside of Lock, No In-Place Updates Example 1: Read-Side Action Taken Outside of Lock, No In-Place Updates
----------------------------------------------------------------------
The best applications are cases where, if reader-writer locking were The best applications are cases where, if reader-writer locking were
used, the read-side lock would be dropped before taking any action used, the read-side lock would be dropped before taking any action
@ -24,7 +26,7 @@ added or deleted, rather than being modified in place.
A straightforward example of this use of RCU may be found in the A straightforward example of this use of RCU may be found in the
system-call auditing support. For example, a reader-writer locked system-call auditing support. For example, a reader-writer locked
implementation of audit_filter_task() might be as follows: implementation of audit_filter_task() might be as follows::
static enum audit_state audit_filter_task(struct task_struct *tsk) static enum audit_state audit_filter_task(struct task_struct *tsk)
{ {
@ -48,7 +50,7 @@ the corresponding value is returned. By the time that this value is acted
on, the list may well have been modified. This makes sense, since if on, the list may well have been modified. This makes sense, since if
you are turning auditing off, it is OK to audit a few extra system calls. you are turning auditing off, it is OK to audit a few extra system calls.
This means that RCU can be easily applied to the read side, as follows: This means that RCU can be easily applied to the read side, as follows::
static enum audit_state audit_filter_task(struct task_struct *tsk) static enum audit_state audit_filter_task(struct task_struct *tsk)
{ {
@ -73,7 +75,7 @@ become list_for_each_entry_rcu(). The _rcu() list-traversal primitives
insert the read-side memory barriers that are required on DEC Alpha CPUs. insert the read-side memory barriers that are required on DEC Alpha CPUs.
The changes to the update side are also straightforward. A reader-writer The changes to the update side are also straightforward. A reader-writer
lock might be used as follows for deletion and insertion: lock might be used as follows for deletion and insertion::
static inline int audit_del_rule(struct audit_rule *rule, static inline int audit_del_rule(struct audit_rule *rule,
struct list_head *list) struct list_head *list)
@ -106,7 +108,7 @@ lock might be used as follows for deletion and insertion:
return 0; return 0;
} }
Following are the RCU equivalents for these two functions: Following are the RCU equivalents for these two functions::
static inline int audit_del_rule(struct audit_rule *rule, static inline int audit_del_rule(struct audit_rule *rule,
struct list_head *list) struct list_head *list)
@ -154,13 +156,13 @@ otherwise cause concurrent readers to fail spectacularly.
So, when readers can tolerate stale data and when entries are either added So, when readers can tolerate stale data and when entries are either added
or deleted, without in-place modification, it is very easy to use RCU! or deleted, without in-place modification, it is very easy to use RCU!
Example 2: Handling In-Place Updates Example 2: Handling In-Place Updates
------------------------------------
The system-call auditing code does not update auditing rules in place. The system-call auditing code does not update auditing rules in place.
However, if it did, reader-writer-locked code to do so might look as However, if it did, reader-writer-locked code to do so might look as
follows (presumably, the field_count is only permitted to decrease, follows (presumably, the field_count is only permitted to decrease,
otherwise, the added fields would need to be filled in): otherwise, the added fields would need to be filled in)::
static inline int audit_upd_rule(struct audit_rule *rule, static inline int audit_upd_rule(struct audit_rule *rule,
struct list_head *list, struct list_head *list,
@ -187,7 +189,7 @@ otherwise, the added fields would need to be filled in):
The RCU version creates a copy, updates the copy, then replaces the old The RCU version creates a copy, updates the copy, then replaces the old
entry with the newly updated entry. This sequence of actions, allowing entry with the newly updated entry. This sequence of actions, allowing
concurrent reads while doing a copy to perform an update, is what gives concurrent reads while doing a copy to perform an update, is what gives
RCU ("read-copy update") its name. The RCU code is as follows: RCU ("read-copy update") its name. The RCU code is as follows::
static inline int audit_upd_rule(struct audit_rule *rule, static inline int audit_upd_rule(struct audit_rule *rule,
struct list_head *list, struct list_head *list,
@ -216,8 +218,8 @@ RCU ("read-copy update") its name. The RCU code is as follows:
Again, this assumes that the caller holds audit_netlink_sem. Normally, Again, this assumes that the caller holds audit_netlink_sem. Normally,
the reader-writer lock would become a spinlock in this sort of code. the reader-writer lock would become a spinlock in this sort of code.
Example 3: Eliminating Stale Data Example 3: Eliminating Stale Data
---------------------------------
The auditing examples above tolerate stale data, as do most algorithms The auditing examples above tolerate stale data, as do most algorithms
that are tracking external state. Because there is a delay from the that are tracking external state. Because there is a delay from the
@ -231,13 +233,16 @@ per-entry spinlock, and, if the "deleted" flag is set, pretends that the
entry does not exist. For this to be helpful, the search function must entry does not exist. For this to be helpful, the search function must
return holding the per-entry spinlock, as ipc_lock() does in fact do. return holding the per-entry spinlock, as ipc_lock() does in fact do.
Quick Quiz: Why does the search function need to return holding the Quick Quiz:
per-entry lock for this deleted-flag technique to be helpful? Why does the search function need to return holding the per-entry lock for
this deleted-flag technique to be helpful?
:ref:`Answer to Quick Quiz <answer_quick_quiz_list>`
If the system-call audit module were to ever need to reject stale data, If the system-call audit module were to ever need to reject stale data,
one way to accomplish this would be to add a "deleted" flag and a "lock" one way to accomplish this would be to add a "deleted" flag and a "lock"
spinlock to the audit_entry structure, and modify audit_filter_task() spinlock to the audit_entry structure, and modify audit_filter_task()
as follows: as follows::
static enum audit_state audit_filter_task(struct task_struct *tsk) static enum audit_state audit_filter_task(struct task_struct *tsk)
{ {
@ -268,7 +273,7 @@ audit_upd_rule() would need additional memory barriers to ensure
that the list_add_rcu() was really executed before the list_del_rcu(). that the list_add_rcu() was really executed before the list_del_rcu().
The audit_del_rule() function would need to set the "deleted" The audit_del_rule() function would need to set the "deleted"
flag under the spinlock as follows: flag under the spinlock as follows::
static inline int audit_del_rule(struct audit_rule *rule, static inline int audit_del_rule(struct audit_rule *rule,
struct list_head *list) struct list_head *list)
@ -290,8 +295,8 @@ flag under the spinlock as follows:
return -EFAULT; /* No matching rule */ return -EFAULT; /* No matching rule */
} }
Summary Summary
-------
Read-mostly list-based data structures that can tolerate stale data are Read-mostly list-based data structures that can tolerate stale data are
the most amenable to use of RCU. The simplest case is where entries are the most amenable to use of RCU. The simplest case is where entries are
@ -302,8 +307,9 @@ If stale data cannot be tolerated, then a "deleted" flag may be used
in conjunction with a per-entry spinlock in order to allow the search in conjunction with a per-entry spinlock in order to allow the search
function to reject newly deleted data. function to reject newly deleted data.
.. _answer_quick_quiz_list:
Answer to Quick Quiz Answer to Quick Quiz:
Why does the search function need to return holding the per-entry Why does the search function need to return holding the per-entry
lock for this deleted-flag technique to be helpful? lock for this deleted-flag technique to be helpful?

92
Documentation/RCU/rcu.rst Normal file
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@ -0,0 +1,92 @@
.. _rcu_doc:
RCU Concepts
============
The basic idea behind RCU (read-copy update) is to split destructive
operations into two parts, one that prevents anyone from seeing the data
item being destroyed, and one that actually carries out the destruction.
A "grace period" must elapse between the two parts, and this grace period
must be long enough that any readers accessing the item being deleted have
since dropped their references. For example, an RCU-protected deletion
from a linked list would first remove the item from the list, wait for
a grace period to elapse, then free the element. See the
Documentation/RCU/listRCU.rst file for more information on using RCU with
linked lists.
Frequently Asked Questions
--------------------------
- Why would anyone want to use RCU?
The advantage of RCU's two-part approach is that RCU readers need
not acquire any locks, perform any atomic instructions, write to
shared memory, or (on CPUs other than Alpha) execute any memory
barriers. The fact that these operations are quite expensive
on modern CPUs is what gives RCU its performance advantages
in read-mostly situations. The fact that RCU readers need not
acquire locks can also greatly simplify deadlock-avoidance code.
- How can the updater tell when a grace period has completed
if the RCU readers give no indication when they are done?
Just as with spinlocks, RCU readers are not permitted to
block, switch to user-mode execution, or enter the idle loop.
Therefore, as soon as a CPU is seen passing through any of these
three states, we know that that CPU has exited any previous RCU
read-side critical sections. So, if we remove an item from a
linked list, and then wait until all CPUs have switched context,
executed in user mode, or executed in the idle loop, we can
safely free up that item.
Preemptible variants of RCU (CONFIG_PREEMPT_RCU) get the
same effect, but require that the readers manipulate CPU-local
counters. These counters allow limited types of blocking within
RCU read-side critical sections. SRCU also uses CPU-local
counters, and permits general blocking within RCU read-side
critical sections. These variants of RCU detect grace periods
by sampling these counters.
- If I am running on a uniprocessor kernel, which can only do one
thing at a time, why should I wait for a grace period?
See the Documentation/RCU/UP.rst file for more information.
- How can I see where RCU is currently used in the Linux kernel?
Search for "rcu_read_lock", "rcu_read_unlock", "call_rcu",
"rcu_read_lock_bh", "rcu_read_unlock_bh", "srcu_read_lock",
"srcu_read_unlock", "synchronize_rcu", "synchronize_net",
"synchronize_srcu", and the other RCU primitives. Or grab one
of the cscope databases from:
(http://www.rdrop.com/users/paulmck/RCU/linuxusage/rculocktab.html).
- What guidelines should I follow when writing code that uses RCU?
See the checklist.txt file in this directory.
- Why the name "RCU"?
"RCU" stands for "read-copy update". The file Documentation/RCU/listRCU.rst
has more information on where this name came from, search for
"read-copy update" to find it.
- I hear that RCU is patented? What is with that?
Yes, it is. There are several known patents related to RCU,
search for the string "Patent" in RTFP.txt to find them.
Of these, one was allowed to lapse by the assignee, and the
others have been contributed to the Linux kernel under GPL.
There are now also LGPL implementations of user-level RCU
available (http://liburcu.org/).
- I hear that RCU needs work in order to support realtime kernels?
Realtime-friendly RCU can be enabled via the CONFIG_PREEMPT_RCU
kernel configuration parameter.
- Where can I find more information on RCU?
See the RTFP.txt file in this directory.
Or point your browser at (http://www.rdrop.com/users/paulmck/RCU/).

89
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@ -1,89 +0,0 @@
RCU Concepts
The basic idea behind RCU (read-copy update) is to split destructive
operations into two parts, one that prevents anyone from seeing the data
item being destroyed, and one that actually carries out the destruction.
A "grace period" must elapse between the two parts, and this grace period
must be long enough that any readers accessing the item being deleted have
since dropped their references. For example, an RCU-protected deletion
from a linked list would first remove the item from the list, wait for
a grace period to elapse, then free the element. See the listRCU.txt
file for more information on using RCU with linked lists.
Frequently Asked Questions
o Why would anyone want to use RCU?
The advantage of RCU's two-part approach is that RCU readers need
not acquire any locks, perform any atomic instructions, write to
shared memory, or (on CPUs other than Alpha) execute any memory
barriers. The fact that these operations are quite expensive
on modern CPUs is what gives RCU its performance advantages
in read-mostly situations. The fact that RCU readers need not
acquire locks can also greatly simplify deadlock-avoidance code.
o How can the updater tell when a grace period has completed
if the RCU readers give no indication when they are done?
Just as with spinlocks, RCU readers are not permitted to
block, switch to user-mode execution, or enter the idle loop.
Therefore, as soon as a CPU is seen passing through any of these
three states, we know that that CPU has exited any previous RCU
read-side critical sections. So, if we remove an item from a
linked list, and then wait until all CPUs have switched context,
executed in user mode, or executed in the idle loop, we can
safely free up that item.
Preemptible variants of RCU (CONFIG_PREEMPT_RCU) get the
same effect, but require that the readers manipulate CPU-local
counters. These counters allow limited types of blocking within
RCU read-side critical sections. SRCU also uses CPU-local
counters, and permits general blocking within RCU read-side
critical sections. These variants of RCU detect grace periods
by sampling these counters.
o If I am running on a uniprocessor kernel, which can only do one
thing at a time, why should I wait for a grace period?
See the UP.txt file in this directory.
o How can I see where RCU is currently used in the Linux kernel?
Search for "rcu_read_lock", "rcu_read_unlock", "call_rcu",
"rcu_read_lock_bh", "rcu_read_unlock_bh", "srcu_read_lock",
"srcu_read_unlock", "synchronize_rcu", "synchronize_net",
"synchronize_srcu", and the other RCU primitives. Or grab one
of the cscope databases from:
http://www.rdrop.com/users/paulmck/RCU/linuxusage/rculocktab.html
o What guidelines should I follow when writing code that uses RCU?
See the checklist.txt file in this directory.
o Why the name "RCU"?
"RCU" stands for "read-copy update". The file listRCU.txt has
more information on where this name came from, search for
"read-copy update" to find it.
o I hear that RCU is patented? What is with that?
Yes, it is. There are several known patents related to RCU,
search for the string "Patent" in RTFP.txt to find them.
Of these, one was allowed to lapse by the assignee, and the
others have been contributed to the Linux kernel under GPL.
There are now also LGPL implementations of user-level RCU
available (http://liburcu.org/).
o I hear that RCU needs work in order to support realtime kernels?
Realtime-friendly RCU can be enabled via the CONFIG_PREEMPT_RCU
kernel configuration parameter.
o Where can I find more information on RCU?
See the RTFP.txt file in this directory.
Or point your browser at http://www.rdrop.com/users/paulmck/RCU/.

2
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View File

@ -1,3 +1,5 @@
:orphan:
======================================================== ========================================================
OpenCAPI (Open Coherent Accelerator Processor Interface) OpenCAPI (Open Coherent Accelerator Processor Interface)
======================================================== ========================================================

2
Documentation/acpi/dsd/leds.txt
View File

@ -96,4 +96,4 @@ where
<URL:http://www.uefi.org/sites/default/files/resources/_DSD-hierarchical-data-extension-UUID-v1.1.pdf>, <URL:http://www.uefi.org/sites/default/files/resources/_DSD-hierarchical-data-extension-UUID-v1.1.pdf>,
referenced 2019-02-21. referenced 2019-02-21.
[7] Documentation/acpi/dsd/data-node-reference.txt [7] Documentation/firmware-guide/acpi/dsd/data-node-references.rst

2
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View File

@ -227,7 +227,7 @@ Configuring the kernel
"make tinyconfig" Configure the tiniest possible kernel. "make tinyconfig" Configure the tiniest possible kernel.
You can find more information on using the Linux kernel config tools You can find more information on using the Linux kernel config tools
in Documentation/kbuild/kconfig.txt. in Documentation/kbuild/kconfig.rst.
- NOTES on ``make config``: - NOTES on ``make config``:

0
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View File

2
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View File

@ -90,7 +90,7 @@ the disk is not available then you have three options:
run a null modem to a second machine and capture the output there run a null modem to a second machine and capture the output there
using your favourite communication program. Minicom works well. using your favourite communication program. Minicom works well.
(3) Use Kdump (see Documentation/kdump/kdump.txt), (3) Use Kdump (see Documentation/kdump/kdump.rst),
extract the kernel ring buffer from old memory with using dmesg extract the kernel ring buffer from old memory with using dmesg
gdbmacro in Documentation/kdump/gdbmacros.txt. gdbmacro in Documentation/kdump/gdbmacros.txt.

1
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View File

@ -9,5 +9,6 @@ are configurable at compile, boot or run time.
.. toctree:: .. toctree::
:maxdepth: 1 :maxdepth: 1
spectre
l1tf l1tf
mds mds

697
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View File

@ -0,0 +1,697 @@
.. SPDX-License-Identifier: GPL-2.0
Spectre Side Channels
=====================
Spectre is a class of side channel attacks that exploit branch prediction
and speculative execution on modern CPUs to read memory, possibly
bypassing access controls. Speculative execution side channel exploits
do not modify memory but attempt to infer privileged data in the memory.
This document covers Spectre variant 1 and Spectre variant 2.
Affected processors
-------------------
Speculative execution side channel methods affect a wide range of modern
high performance processors, since most modern high speed processors
use branch prediction and speculative execution.
The following CPUs are vulnerable:
- Intel Core, Atom, Pentium, and Xeon processors
- AMD Phenom, EPYC, and Zen processors
- IBM POWER and zSeries processors
- Higher end ARM processors
- Apple CPUs
- Higher end MIPS CPUs
- Likely most other high performance CPUs. Contact your CPU vendor for details.
Whether a processor is affected or not can be read out from the Spectre
vulnerability files in sysfs. See :ref:`spectre_sys_info`.
Related CVEs
------------
The following CVE entries describe Spectre variants:
============= ======================= =================
CVE-2017-5753 Bounds check bypass Spectre variant 1
CVE-2017-5715 Branch target injection Spectre variant 2
============= ======================= =================
Problem
-------
CPUs use speculative operations to improve performance. That may leave
traces of memory accesses or computations in the processor's caches,
buffers, and branch predictors. Malicious software may be able to
influence the speculative execution paths, and then use the side effects
of the speculative execution in the CPUs' caches and buffers to infer
privileged data touched during the speculative execution.
Spectre variant 1 attacks take advantage of speculative execution of
conditional branches, while Spectre variant 2 attacks use speculative
execution of indirect branches to leak privileged memory.
See :ref:`[1] <spec_ref1>` :ref:`[5] <spec_ref5>` :ref:`[7] <spec_ref7>`
:ref:`[10] <spec_ref10>` :ref:`[11] <spec_ref11>`.
Spectre variant 1 (Bounds Check Bypass)
---------------------------------------
The bounds check bypass attack :ref:`[2] <spec_ref2>` takes advantage
of speculative execution that bypasses conditional branch instructions
used for memory access bounds check (e.g. checking if the index of an
array results in memory access within a valid range). This results in
memory accesses to invalid memory (with out-of-bound index) that are
done speculatively before validation checks resolve. Such speculative
memory accesses can leave side effects, creating side channels which
leak information to the attacker.
There are some extensions of Spectre variant 1 attacks for reading data
over the network, see :ref:`[12] <spec_ref12>`. However such attacks
are difficult, low bandwidth, fragile, and are considered low risk.
Spectre variant 2 (Branch Target Injection)
-------------------------------------------
The branch target injection attack takes advantage of speculative
execution of indirect branches :ref:`[3] <spec_ref3>`. The indirect
branch predictors inside the processor used to guess the target of
indirect branches can be influenced by an attacker, causing gadget code
to be speculatively executed, thus exposing sensitive data touched by
the victim. The side effects left in the CPU's caches during speculative
execution can be measured to infer data values.
.. _poison_btb:
In Spectre variant 2 attacks, the attacker can steer speculative indirect
branches in the victim to gadget code by poisoning the branch target
buffer of a CPU used for predicting indirect branch addresses. Such
poisoning could be done by indirect branching into existing code,
with the address offset of the indirect branch under the attacker's
control. Since the branch prediction on impacted hardware does not
fully disambiguate branch address and uses the offset for prediction,
this could cause privileged code's indirect branch to jump to a gadget
code with the same offset.
The most useful gadgets take an attacker-controlled input parameter (such
as a register value) so that the memory read can be controlled. Gadgets
without input parameters might be possible, but the attacker would have
very little control over what memory can be read, reducing the risk of
the attack revealing useful data.
One other variant 2 attack vector is for the attacker to poison the
return stack buffer (RSB) :ref:`[13] <spec_ref13>` to cause speculative
subroutine return instruction execution to go to a gadget. An attacker's
imbalanced subroutine call instructions might "poison" entries in the
return stack buffer which are later consumed by a victim's subroutine
return instructions. This attack can be mitigated by flushing the return
stack buffer on context switch, or virtual machine (VM) exit.
On systems with simultaneous multi-threading (SMT), attacks are possible
from the sibling thread, as level 1 cache and branch target buffer
(BTB) may be shared between hardware threads in a CPU core. A malicious
program running on the sibling thread may influence its peer's BTB to
steer its indirect branch speculations to gadget code, and measure the
speculative execution's side effects left in level 1 cache to infer the
victim's data.
Attack scenarios
----------------
The following list of attack scenarios have been anticipated, but may
not cover all possible attack vectors.
1. A user process attacking the kernel
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The attacker passes a parameter to the kernel via a register or
via a known address in memory during a syscall. Such parameter may
be used later by the kernel as an index to an array or to derive
a pointer for a Spectre variant 1 attack. The index or pointer
is invalid, but bound checks are bypassed in the code branch taken
for speculative execution. This could cause privileged memory to be
accessed and leaked.
For kernel code that has been identified where data pointers could
potentially be influenced for Spectre attacks, new "nospec" accessor
macros are used to prevent speculative loading of data.
Spectre variant 2 attacker can :ref:`poison <poison_btb>` the branch
target buffer (BTB) before issuing syscall to launch an attack.
After entering the kernel, the kernel could use the poisoned branch
target buffer on indirect jump and jump to gadget code in speculative
execution.
If an attacker tries to control the memory addresses leaked during
speculative execution, he would also need to pass a parameter to the
gadget, either through a register or a known address in memory. After
the gadget has executed, he can measure the side effect.
The kernel can protect itself against consuming poisoned branch
target buffer entries by using return trampolines (also known as
"retpoline") :ref:`[3] <spec_ref3>` :ref:`[9] <spec_ref9>` for all
indirect branches. Return trampolines trap speculative execution paths
to prevent jumping to gadget code during speculative execution.
x86 CPUs with Enhanced Indirect Branch Restricted Speculation
(Enhanced IBRS) available in hardware should use the feature to
mitigate Spectre variant 2 instead of retpoline. Enhanced IBRS is
more efficient than retpoline.
There may be gadget code in firmware which could be exploited with
Spectre variant 2 attack by a rogue user process. To mitigate such
attacks on x86, Indirect Branch Restricted Speculation (IBRS) feature
is turned on before the kernel invokes any firmware code.
2. A user process attacking another user process
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
A malicious user process can try to attack another user process,
either via a context switch on the same hardware thread, or from the
sibling hyperthread sharing a physical processor core on simultaneous
multi-threading (SMT) system.
Spectre variant 1 attacks generally require passing parameters
between the processes, which needs a data passing relationship, such
as remote procedure calls (RPC). Those parameters are used in gadget
code to derive invalid data pointers accessing privileged memory in
the attacked process.
Spectre variant 2 attacks can be launched from a rogue process by
:ref:`poisoning <poison_btb>` the branch target buffer. This can
influence the indirect branch targets for a victim process that either
runs later on the same hardware thread, or running concurrently on
a sibling hardware thread sharing the same physical core.
A user process can protect itself against Spectre variant 2 attacks
by using the prctl() syscall to disable indirect branch speculation
for itself. An administrator can also cordon off an unsafe process
from polluting the branch target buffer by disabling the process's
indirect branch speculation. This comes with a performance cost
from not using indirect branch speculation and clearing the branch
target buffer. When SMT is enabled on x86, for a process that has
indirect branch speculation disabled, Single Threaded Indirect Branch
Predictors (STIBP) :ref:`[4] <spec_ref4>` are turned on to prevent the
sibling thread from controlling branch target buffer. In addition,
the Indirect Branch Prediction Barrier (IBPB) is issued to clear the
branch target buffer when context switching to and from such process.
On x86, the return stack buffer is stuffed on context switch.
This prevents the branch target buffer from being used for branch
prediction when the return stack buffer underflows while switching to
a deeper call stack. Any poisoned entries in the return stack buffer
left by the previous process will also be cleared.
User programs should use address space randomization to make attacks
more difficult (Set /proc/sys/kernel/randomize_va_space = 1 or 2).
3. A virtualized guest attacking the host
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The attack mechanism is similar to how user processes attack the
kernel. The kernel is entered via hyper-calls or other virtualization
exit paths.
For Spectre variant 1 attacks, rogue guests can pass parameters
(e.g. in registers) via hyper-calls to derive invalid pointers to
speculate into privileged memory after entering the kernel. For places
where such kernel code has been identified, nospec accessor macros
are used to stop speculative memory access.
For Spectre variant 2 attacks, rogue guests can :ref:`poison
<poison_btb>` the branch target buffer or return stack buffer, causing
the kernel to jump to gadget code in the speculative execution paths.
To mitigate variant 2, the host kernel can use return trampolines
for indirect branches to bypass the poisoned branch target buffer,
and flushing the return stack buffer on VM exit. This prevents rogue
guests from affecting indirect branching in the host kernel.
To protect host processes from rogue guests, host processes can have
indirect branch speculation disabled via prctl(). The branch target
buffer is cleared before context switching to such processes.
4. A virtualized guest attacking other guest
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
A rogue guest may attack another guest to get data accessible by the
other guest.
Spectre variant 1 attacks are possible if parameters can be passed
between guests. This may be done via mechanisms such as shared memory
or message passing. Such parameters could be used to derive data
pointers to privileged data in guest. The privileged data could be
accessed by gadget code in the victim's speculation paths.
Spectre variant 2 attacks can be launched from a rogue guest by
:ref:`poisoning <poison_btb>` the branch target buffer or the return
stack buffer. Such poisoned entries could be used to influence
speculation execution paths in the victim guest.
Linux kernel mitigates attacks to other guests running in the same
CPU hardware thread by flushing the return stack buffer on VM exit,
and clearing the branch target buffer before switching to a new guest.
If SMT is used, Spectre variant 2 attacks from an untrusted guest
in the sibling hyperthread can be mitigated by the administrator,
by turning off the unsafe guest's indirect branch speculation via
prctl(). A guest can also protect itself by turning on microcode
based mitigations (such as IBPB or STIBP on x86) within the guest.
.. _spectre_sys_info:
Spectre system information
--------------------------
The Linux kernel provides a sysfs interface to enumerate the current
mitigation status of the system for Spectre: whether the system is
vulnerable, and which mitigations are active.
The sysfs file showing Spectre variant 1 mitigation status is:
/sys/devices/system/cpu/vulnerabilities/spectre_v1
The possible values in this file are:
======================================= =================================
'Mitigation: __user pointer sanitation' Protection in kernel on a case by
case base with explicit pointer
sanitation.
======================================= =================================
However, the protections are put in place on a case by case basis,
and there is no guarantee that all possible attack vectors for Spectre
variant 1 are covered.
The spectre_v2 kernel file reports if the kernel has been compiled with
retpoline mitigation or if the CPU has hardware mitigation, and if the
CPU has support for additional process-specific mitigation.
This file also reports CPU features enabled by microcode to mitigate
attack between user processes:
1. Indirect Branch Prediction Barrier (IBPB) to add additional
isolation between processes of different users.
2. Single Thread Indirect Branch Predictors (STIBP) to add additional
isolation between CPU threads running on the same core.
These CPU features may impact performance when used and can be enabled
per process on a case-by-case base.
The sysfs file showing Spectre variant 2 mitigation status is:
/sys/devices/system/cpu/vulnerabilities/spectre_v2
The possible values in this file are:
- Kernel status:
==================================== =================================
'Not affected' The processor is not vulnerable
'Vulnerable' Vulnerable, no mitigation
'Mitigation: Full generic retpoline' Software-focused mitigation
'Mitigation: Full AMD retpoline' AMD-specific software mitigation
'Mitigation: Enhanced IBRS' Hardware-focused mitigation
==================================== =================================
- Firmware status: Show if Indirect Branch Restricted Speculation (IBRS) is
used to protect against Spectre variant 2 attacks when calling firmware (x86 only).
========== =============================================================
'IBRS_FW' Protection against user program attacks when calling firmware
========== =============================================================
- Indirect branch prediction barrier (IBPB) status for protection between
processes of different users. This feature can be controlled through
prctl() per process, or through kernel command line options. This is
an x86 only feature. For more details see below.
=================== ========================================================
'IBPB: disabled' IBPB unused
'IBPB: always-on' Use IBPB on all tasks
'IBPB: conditional' Use IBPB on SECCOMP or indirect branch restricted tasks
=================== ========================================================
- Single threaded indirect branch prediction (STIBP) status for protection
between different hyper threads. This feature can be controlled through
prctl per process, or through kernel command line options. This is x86
only feature. For more details see below.
==================== ========================================================
'STIBP: disabled' STIBP unused
'STIBP: forced' Use STIBP on all tasks
'STIBP: conditional' Use STIBP on SECCOMP or indirect branch restricted tasks
==================== ========================================================
- Return stack buffer (RSB) protection status:
============= ===========================================
'RSB filling' Protection of RSB on context switch enabled
============= ===========================================
Full mitigation might require a microcode update from the CPU
vendor. When the necessary microcode is not available, the kernel will
report vulnerability.
Turning on mitigation for Spectre variant 1 and Spectre variant 2
-----------------------------------------------------------------
1. Kernel mitigation
^^^^^^^^^^^^^^^^^^^^
For the Spectre variant 1, vulnerable kernel code (as determined
by code audit or scanning tools) is annotated on a case by case
basis to use nospec accessor macros for bounds clipping :ref:`[2]
<spec_ref2>` to avoid any usable disclosure gadgets. However, it may
not cover all attack vectors for Spectre variant 1.
For Spectre variant 2 mitigation, the compiler turns indirect calls or
jumps in the kernel into equivalent return trampolines (retpolines)
:ref:`[3] <spec_ref3>` :ref:`[9] <spec_ref9>` to go to the target
addresses. Speculative execution paths under retpolines are trapped
in an infinite loop to prevent any speculative execution jumping to
a gadget.
To turn on retpoline mitigation on a vulnerable CPU, the kernel
needs to be compiled with a gcc compiler that supports the
-mindirect-branch=thunk-extern -mindirect-branch-register options.
If the kernel is compiled with a Clang compiler, the compiler needs
to support -mretpoline-external-thunk option. The kernel config
CONFIG_RETPOLINE needs to be turned on, and the CPU needs to run with
the latest updated microcode.
On Intel Skylake-era systems the mitigation covers most, but not all,
cases. See :ref:`[3] <spec_ref3>` for more details.
On CPUs with hardware mitigation for Spectre variant 2 (e.g. Enhanced
IBRS on x86), retpoline is automatically disabled at run time.
The retpoline mitigation is turned on by default on vulnerable
CPUs. It can be forced on or off by the administrator
via the kernel command line and sysfs control files. See
:ref:`spectre_mitigation_control_command_line`.
On x86, indirect branch restricted speculation is turned on by default
before invoking any firmware code to prevent Spectre variant 2 exploits
using the firmware.
Using kernel address space randomization (CONFIG_RANDOMIZE_SLAB=y
and CONFIG_SLAB_FREELIST_RANDOM=y in the kernel configuration) makes
attacks on the kernel generally more difficult.
2. User program mitigation
^^^^^^^^^^^^^^^^^^^^^^^^^^
User programs can mitigate Spectre variant 1 using LFENCE or "bounds
clipping". For more details see :ref:`[2] <spec_ref2>`.
For Spectre variant 2 mitigation, individual user programs
can be compiled with return trampolines for indirect branches.
This protects them from consuming poisoned entries in the branch
target buffer left by malicious software. Alternatively, the
programs can disable their indirect branch speculation via prctl()
(See :ref:`Documentation/userspace-api/spec_ctrl.rst <set_spec_ctrl>`).
On x86, this will turn on STIBP to guard against attacks from the
sibling thread when the user program is running, and use IBPB to
flush the branch target buffer when switching to/from the program.
Restricting indirect branch speculation on a user program will
also prevent the program from launching a variant 2 attack
on x86. All sand-boxed SECCOMP programs have indirect branch
speculation restricted by default. Administrators can change
that behavior via the kernel command line and sysfs control files.
See :ref:`spectre_mitigation_control_command_line`.
Programs that disable their indirect branch speculation will have
more overhead and run slower.
User programs should use address space randomization
(/proc/sys/kernel/randomize_va_space = 1 or 2) to make attacks more
difficult.
3. VM mitigation
^^^^^^^^^^^^^^^^
Within the kernel, Spectre variant 1 attacks from rogue guests are
mitigated on a case by case basis in VM exit paths. Vulnerable code
uses nospec accessor macros for "bounds clipping", to avoid any
usable disclosure gadgets. However, this may not cover all variant
1 attack vectors.
For Spectre variant 2 attacks from rogue guests to the kernel, the
Linux kernel uses retpoline or Enhanced IBRS to prevent consumption of
poisoned entries in branch target buffer left by rogue guests. It also
flushes the return stack buffer on every VM exit to prevent a return
stack buffer underflow so poisoned branch target buffer could be used,
or attacker guests leaving poisoned entries in the return stack buffer.
To mitigate guest-to-guest attacks in the same CPU hardware thread,
the branch target buffer is sanitized by flushing before switching
to a new guest on a CPU.
The above mitigations are turned on by default on vulnerable CPUs.
To mitigate guest-to-guest attacks from sibling thread when SMT is
in use, an untrusted guest running in the sibling thread can have
its indirect branch speculation disabled by administrator via prctl().
The kernel also allows guests to use any microcode based mitigation
they choose to use (such as IBPB or STIBP on x86) to protect themselves.
.. _spectre_mitigation_control_command_line:
Mitigation control on the kernel command line
---------------------------------------------
Spectre variant 2 mitigation can be disabled or force enabled at the
kernel command line.
nospectre_v2
[X86] Disable all mitigations for the Spectre variant 2
(indirect branch prediction) vulnerability. System may
allow data leaks with this option, which is equivalent
to spectre_v2=off.
spectre_v2=
[X86] Control mitigation of Spectre variant 2
(indirect branch speculation) vulnerability.
The default operation protects the kernel from
user space attacks.
on
unconditionally enable, implies
spectre_v2_user=on
off
unconditionally disable, implies
spectre_v2_user=off
auto
kernel detects whether your CPU model is
vulnerable
Selecting 'on' will, and 'auto' may, choose a
mitigation method at run time according to the
CPU, the available microcode, the setting of the
CONFIG_RETPOLINE configuration option, and the
compiler with which the kernel was built.
Selecting 'on' will also enable the mitigation
against user space to user space task attacks.
Selecting 'off' will disable both the kernel and
the user space protections.
Specific mitigations can also be selected manually:
retpoline
replace indirect branches
retpoline,generic
google's original retpoline
retpoline,amd
AMD-specific minimal thunk
Not specifying this option is equivalent to
spectre_v2=auto.
For user space mitigation:
spectre_v2_user=
[X86] Control mitigation of Spectre variant 2
(indirect branch speculation) vulnerability between
user space tasks
on
Unconditionally enable mitigations. Is
enforced by spectre_v2=on
off
Unconditionally disable mitigations. Is
enforced by spectre_v2=off
prctl
Indirect branch speculation is enabled,
but mitigation can be enabled via prctl
per thread. The mitigation control state
is inherited on fork.
prctl,ibpb
Like "prctl" above, but only STIBP is
controlled per thread. IBPB is issued
always when switching between different user
space processes.
seccomp
Same as "prctl" above, but all seccomp
threads will enable the mitigation unless
they explicitly opt out.
seccomp,ibpb
Like "seccomp" above, but only STIBP is
controlled per thread. IBPB is issued
always when switching between different
user space processes.
auto
Kernel selects the mitigation depending on
the available CPU features and vulnerability.
Default mitigation:
If CONFIG_SECCOMP=y then "seccomp", otherwise "prctl"
Not specifying this option is equivalent to
spectre_v2_user=auto.
In general the kernel by default selects
reasonable mitigations for the current CPU. To
disable Spectre variant 2 mitigations, boot with
spectre_v2=off. Spectre variant 1 mitigations
cannot be disabled.
Mitigation selection guide
--------------------------
1. Trusted userspace
^^^^^^^^^^^^^^^^^^^^
If all userspace applications are from trusted sources and do not
execute externally supplied untrusted code, then the mitigations can
be disabled.
2. Protect sensitive programs
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
For security-sensitive programs that have secrets (e.g. crypto
keys), protection against Spectre variant 2 can be put in place by
disabling indirect branch speculation when the program is running
(See :ref:`Documentation/userspace-api/spec_ctrl.rst <set_spec_ctrl>`).
3. Sandbox untrusted programs
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Untrusted programs that could be a source of attacks can be cordoned
off by disabling their indirect branch speculation when they are run
(See :ref:`Documentation/userspace-api/spec_ctrl.rst <set_spec_ctrl>`).
This prevents untrusted programs from polluting the branch target
buffer. All programs running in SECCOMP sandboxes have indirect
branch speculation restricted by default. This behavior can be
changed via the kernel command line and sysfs control files. See
:ref:`spectre_mitigation_control_command_line`.
3. High security mode
^^^^^^^^^^^^^^^^^^^^^
All Spectre variant 2 mitigations can be forced on
at boot time for all programs (See the "on" option in
:ref:`spectre_mitigation_control_command_line`). This will add
overhead as indirect branch speculations for all programs will be
restricted.
On x86, branch target buffer will be flushed with IBPB when switching
to a new program. STIBP is left on all the time to protect programs
against variant 2 attacks originating from programs running on
sibling threads.
Alternatively, STIBP can be used only when running programs
whose indirect branch speculation is explicitly disabled,
while IBPB is still used all the time when switching to a new
program to clear the branch target buffer (See "ibpb" option in
:ref:`spectre_mitigation_control_command_line`). This "ibpb" option
has less performance cost than the "on" option, which leaves STIBP
on all the time.
References on Spectre
---------------------
Intel white papers:
.. _spec_ref1:
[1] `Intel analysis of speculative execution side channels <https://newsroom.intel.com/wp-content/uploads/sites/11/2018/01/Intel-Analysis-of-Speculative-Execution-Side-Channels.pdf>`_.
.. _spec_ref2:
[2] `Bounds check bypass <https://software.intel.com/security-software-guidance/software-guidance/bounds-check-bypass>`_.
.. _spec_ref3:
[3] `Deep dive: Retpoline: A branch target injection mitigation <https://software.intel.com/security-software-guidance/insights/deep-dive-retpoline-branch-target-injection-mitigation>`_.
.. _spec_ref4:
[4] `Deep Dive: Single Thread Indirect Branch Predictors <https://software.intel.com/security-software-guidance/insights/deep-dive-single-thread-indirect-branch-predictors>`_.
AMD white papers:
.. _spec_ref5:
[5] `AMD64 technology indirect branch control extension <https://developer.amd.com/wp-content/resources/Architecture_Guidelines_Update_Indirect_Branch_Control.pdf>`_.
.. _spec_ref6:
[6] `Software techniques for managing speculation on AMD processors <https://developer.amd.com/wp-content/resources/90343-B_SoftwareTechniquesforManagingSpeculation_WP_7-18Update_FNL.pdf>`_.
ARM white papers:
.. _spec_ref7:
[7] `Cache speculation side-channels <https://developer.arm.com/support/arm-security-updates/speculative-processor-vulnerability/download-the-whitepaper>`_.
.. _spec_ref8:
[8] `Cache speculation issues update <https://developer.arm.com/support/arm-security-updates/speculative-processor-vulnerability/latest-updates/cache-speculation-issues-update>`_.
Google white paper:
.. _spec_ref9:
[9] `Retpoline: a software construct for preventing branch-target-injection <https://support.google.com/faqs/answer/7625886>`_.
MIPS white paper:
.. _spec_ref10:
[10] `MIPS: response on speculative execution and side channel vulnerabilities <https://www.mips.com/blog/mips-response-on-speculative-execution-and-side-channel-vulnerabilities/>`_.
Academic papers:
.. _spec_ref11:
[11] `Spectre Attacks: Exploiting Speculative Execution <https://spectreattack.com/spectre.pdf>`_.
.. _spec_ref12:
[12] `NetSpectre: Read Arbitrary Memory over Network <https://arxiv.org/abs/1807.10535>`_.
.. _spec_ref13:
[13] `Spectre Returns! Speculation Attacks using the Return Stack Buffer <https://www.usenix.org/system/files/conference/woot18/woot18-paper-koruyeh.pdf>`_.

1
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@ -70,6 +70,7 @@ configure specific aspects of kernel behavior to your liking.
ras ras
bcache bcache
ext4 ext4
binderfs
pm/index pm/index
thunderbolt thunderbolt
LSM/index LSM/index

10
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@ -9,11 +9,11 @@ and sorted into English Dictionary order (defined as ignoring all
punctuation and sorting digits before letters in a case insensitive punctuation and sorting digits before letters in a case insensitive
manner), and with descriptions where known. manner), and with descriptions where known.
The kernel parses parameters from the kernel command line up to "--"; The kernel parses parameters from the kernel command line up to "``--``";
if it doesn't recognize a parameter and it doesn't contain a '.', the if it doesn't recognize a parameter and it doesn't contain a '.', the
parameter gets passed to init: parameters with '=' go into init's parameter gets passed to init: parameters with '=' go into init's
environment, others are passed as command line arguments to init. environment, others are passed as command line arguments to init.
Everything after "--" is passed as an argument to init. Everything after "``--``" is passed as an argument to init.
Module parameters can be specified in two ways: via the kernel command Module parameters can be specified in two ways: via the kernel command
line with a module name prefix, or via modprobe, e.g.:: line with a module name prefix, or via modprobe, e.g.::
@ -167,7 +167,7 @@ parameter is applicable::
X86-32 X86-32, aka i386 architecture is enabled. X86-32 X86-32, aka i386 architecture is enabled.
X86-64 X86-64 architecture is enabled. X86-64 X86-64 architecture is enabled.
More X86-64 boot options can be found in More X86-64 boot options can be found in
Documentation/x86/x86_64/boot-options.txt . Documentation/x86/x86_64/boot-options.rst.
X86 Either 32-bit or 64-bit x86 (same as X86-32+X86-64) X86 Either 32-bit or 64-bit x86 (same as X86-32+X86-64)
X86_UV SGI UV support is enabled. X86_UV SGI UV support is enabled.
XEN Xen support is enabled XEN Xen support is enabled
@ -181,10 +181,10 @@ In addition, the following text indicates that the option::
Parameters denoted with BOOT are actually interpreted by the boot Parameters denoted with BOOT are actually interpreted by the boot
loader, and have no meaning to the kernel directly. loader, and have no meaning to the kernel directly.
Do not modify the syntax of boot loader parameters without extreme Do not modify the syntax of boot loader parameters without extreme
need or coordination with <Documentation/x86/boot.txt>. need or coordination with <Documentation/x86/boot.rst>.
There are also arch-specific kernel-parameters not documented here. There are also arch-specific kernel-parameters not documented here.
See for example <Documentation/x86/x86_64/boot-options.txt>. See for example <Documentation/x86/x86_64/boot-options.rst>.
Note that ALL kernel parameters listed below are CASE SENSITIVE, and that Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
a trailing = on the name of any parameter states that that parameter will a trailing = on the name of any parameter states that that parameter will

38
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@ -53,7 +53,7 @@
ACPI_DEBUG_PRINT statements, e.g., ACPI_DEBUG_PRINT statements, e.g.,
ACPI_DEBUG_PRINT((ACPI_DB_INFO, ... ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
The debug_level mask defaults to "info". See The debug_level mask defaults to "info". See
Documentation/acpi/debug.txt for more information about Documentation/firmware-guide/acpi/debug.rst for more information about
debug layers and levels. debug layers and levels.
Enable processor driver info messages: Enable processor driver info messages:
@ -708,14 +708,14 @@
[KNL, x86_64] select a region under 4G first, and [KNL, x86_64] select a region under 4G first, and
fall back to reserve region above 4G when '@offset' fall back to reserve region above 4G when '@offset'
hasn't been specified. hasn't been specified.
See Documentation/kdump/kdump.txt for further details. See Documentation/kdump/kdump.rst for further details.
crashkernel=range1:size1[,range2:size2,...][@offset] crashkernel=range1:size1[,range2:size2,...][@offset]
[KNL] Same as above, but depends on the memory [KNL] Same as above, but depends on the memory
in the running system. The syntax of range is in the running system. The syntax of range is
start-[end] where start and end are both start-[end] where start and end are both
a memory unit (amount[KMG]). See also a memory unit (amount[KMG]). See also
Documentation/kdump/kdump.txt for an example. Documentation/kdump/kdump.rst for an example.
crashkernel=size[KMG],high crashkernel=size[KMG],high
[KNL, x86_64] range could be above 4G. Allow kernel [KNL, x86_64] range could be above 4G. Allow kernel
@ -932,7 +932,7 @@
edid/1680x1050.bin, or edid/1920x1080.bin is given edid/1680x1050.bin, or edid/1920x1080.bin is given
and no file with the same name exists. Details and and no file with the same name exists. Details and
instructions how to build your own EDID data are instructions how to build your own EDID data are
available in Documentation/EDID/HOWTO.txt. An EDID available in Documentation/EDID/howto.rst. An EDID
data set will only be used for a particular connector, data set will only be used for a particular connector,
if its name and a colon are prepended to the EDID if its name and a colon are prepended to the EDID
name. Each connector may use a unique EDID data name. Each connector may use a unique EDID data
@ -963,7 +963,7 @@
for details. for details.
nompx [X86] Disables Intel Memory Protection Extensions. nompx [X86] Disables Intel Memory Protection Extensions.
See Documentation/x86/intel_mpx.txt for more See Documentation/x86/intel_mpx.rst for more
information about the feature. information about the feature.
nopku [X86] Disable Memory Protection Keys CPU feature found nopku [X86] Disable Memory Protection Keys CPU feature found
@ -1189,7 +1189,7 @@
that is to be dynamically loaded by Linux. If there are that is to be dynamically loaded by Linux. If there are
multiple variables with the same name but with different multiple variables with the same name but with different
vendor GUIDs, all of them will be loaded. See vendor GUIDs, all of them will be loaded. See
Documentation/acpi/ssdt-overlays.txt for details. Documentation/admin-guide/acpi/ssdt-overlays.rst for details.
eisa_irq_edge= [PARISC,HW] eisa_irq_edge= [PARISC,HW]
@ -1209,7 +1209,7 @@
Specifies physical address of start of kernel core Specifies physical address of start of kernel core
image elf header and optionally the size. Generally image elf header and optionally the size. Generally
kexec loader will pass this option to capture kernel. kexec loader will pass this option to capture kernel.
See Documentation/kdump/kdump.txt for details. See Documentation/kdump/kdump.rst for details.
enable_mtrr_cleanup [X86] enable_mtrr_cleanup [X86]
The kernel tries to adjust MTRR layout from continuous The kernel tries to adjust MTRR layout from continuous
@ -1388,9 +1388,6 @@
Valid parameters: "on", "off" Valid parameters: "on", "off"
Default: "on" Default: "on"
hisax= [HW,ISDN]
See Documentation/isdn/README.HiSax.
hlt [BUGS=ARM,SH] hlt [BUGS=ARM,SH]
hpet= [X86-32,HPET] option to control HPET usage hpet= [X86-32,HPET] option to control HPET usage
@ -1507,7 +1504,7 @@
Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
.vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
.cdrom .chs .ignore_cable are additional options .cdrom .chs .ignore_cable are additional options
See Documentation/ide/ide.txt. See Documentation/ide/ide.rst.
ide-generic.probe-mask= [HW] (E)IDE subsystem ide-generic.probe-mask= [HW] (E)IDE subsystem
Format: <int> Format: <int>
@ -2383,7 +2380,7 @@
mce [X86-32] Machine Check Exception mce [X86-32] Machine Check Exception
mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt mce=option [X86-64] See Documentation/x86/x86_64/boot-options.rst
md= [HW] RAID subsystems devices and level md= [HW] RAID subsystems devices and level
See Documentation/admin-guide/md.rst. See Documentation/admin-guide/md.rst.
@ -2439,7 +2436,7 @@
set according to the set according to the
CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE kernel config CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE kernel config
option. option.
See Documentation/memory-hotplug.txt. See Documentation/admin-guide/mm/memory-hotplug.rst.
memmap=exactmap [KNL,X86] Enable setting of an exact memmap=exactmap [KNL,X86] Enable setting of an exact
E820 memory map, as specified by the user. E820 memory map, as specified by the user.
@ -2528,7 +2525,7 @@
mem_encrypt=on: Activate SME mem_encrypt=on: Activate SME
mem_encrypt=off: Do not activate SME mem_encrypt=off: Do not activate SME
Refer to Documentation/x86/amd-memory-encryption.txt Refer to Documentation/virtual/kvm/amd-memory-encryption.rst
for details on when memory encryption can be activated. for details on when memory encryption can be activated.
mem_sleep_default= [SUSPEND] Default system suspend mode: mem_sleep_default= [SUSPEND] Default system suspend mode:
@ -2836,8 +2833,9 @@
0 - turn hardlockup detector in nmi_watchdog off 0 - turn hardlockup detector in nmi_watchdog off
1 - turn hardlockup detector in nmi_watchdog on 1 - turn hardlockup detector in nmi_watchdog on
When panic is specified, panic when an NMI watchdog When panic is specified, panic when an NMI watchdog
timeout occurs (or 'nopanic' to override the opposite timeout occurs (or 'nopanic' to not panic on an NMI
default). To disable both hard and soft lockup detectors, watchdog, if CONFIG_BOOTPARAM_HARDLOCKUP_PANIC is set)
To disable both hard and soft lockup detectors,
please see 'nowatchdog'. please see 'nowatchdog'.
This is useful when you use a panic=... timeout and This is useful when you use a panic=... timeout and
need the box quickly up again. need the box quickly up again.
@ -3528,7 +3526,7 @@
See Documentation/blockdev/paride.txt. See Documentation/blockdev/paride.txt.
pirq= [SMP,APIC] Manual mp-table setup pirq= [SMP,APIC] Manual mp-table setup
See Documentation/x86/i386/IO-APIC.txt. See Documentation/x86/i386/IO-APIC.rst.
plip= [PPT,NET] Parallel port network link plip= [PPT,NET] Parallel port network link
Format: { parport<nr> | timid | 0 } Format: { parport<nr> | timid | 0 }
@ -5032,7 +5030,7 @@
vector=percpu: enable percpu vector domain vector=percpu: enable percpu vector domain
video= [FB] Frame buffer configuration video= [FB] Frame buffer configuration
See Documentation/fb/modedb.txt. See Documentation/fb/modedb.rst.
video.brightness_switch_enabled= [0,1] video.brightness_switch_enabled= [0,1]
If set to 1, on receiving an ACPI notify event If set to 1, on receiving an ACPI notify event
@ -5060,7 +5058,7 @@
Can be used multiple times for multiple devices. Can be used multiple times for multiple devices.
vga= [BOOT,X86-32] Select a particular video mode vga= [BOOT,X86-32] Select a particular video mode
See Documentation/x86/boot.txt and See Documentation/x86/boot.rst and
Documentation/svga.txt. Documentation/svga.txt.
Use vga=ask for menu. Use vga=ask for menu.
This is actually a boot loader parameter; the value is This is actually a boot loader parameter; the value is
@ -5167,7 +5165,7 @@
Default: 3 = cyan. Default: 3 = cyan.
watchdog timers [HW,WDT] For information on watchdog timers, watchdog timers [HW,WDT] For information on watchdog timers,
see Documentation/watchdog/watchdog-parameters.txt see Documentation/watchdog/watchdog-parameters.rst
or other driver-specific files in the or other driver-specific files in the
Documentation/watchdog/ directory. Documentation/watchdog/ directory.

5
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@ -165,5 +165,6 @@ write-through caching.
======== ========
See Also See Also
======== ========
.. [1] https://www.uefi.org/sites/default/files/resources/ACPI_6_2.pdf
Section 5.2.27 [1] https://www.uefi.org/sites/default/files/resources/ACPI_6_2.pdf
- Section 5.2.27

2
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@ -199,7 +199,7 @@ Architecture (MCA)\ [#f3]_.
mode). mode).
.. [#f3] For more details about the Machine Check Architecture (MCA), .. [#f3] For more details about the Machine Check Architecture (MCA),
please read Documentation/x86/x86_64/machinecheck at the Kernel tree. please read Documentation/x86/x86_64/machinecheck.rst at the Kernel tree.
EDAC - Error Detection And Correction EDAC - Error Detection And Correction
************************************* *************************************

63
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@ -1,3 +1,6 @@
Introduction
============
ATA over Ethernet is a network protocol that provides simple access to ATA over Ethernet is a network protocol that provides simple access to
block storage on the LAN. block storage on the LAN.
@ -22,7 +25,8 @@ document the use of the driver and are not necessary if you install
the aoetools. the aoetools.
CREATING DEVICE NODES Creating Device Nodes
=====================
Users of udev should find the block device nodes created Users of udev should find the block device nodes created
automatically, but to create all the necessary device nodes, use the automatically, but to create all the necessary device nodes, use the
@ -38,7 +42,8 @@ CREATING DEVICE NODES
confusing when an AoE device is not present the first time the a confusing when an AoE device is not present the first time the a
command is run but appears a second later. command is run but appears a second later.
USING DEVICE NODES Using Device Nodes
==================
"cat /dev/etherd/err" blocks, waiting for error diagnostic output, "cat /dev/etherd/err" blocks, waiting for error diagnostic output,
like any retransmitted packets. like any retransmitted packets.
@ -55,7 +60,7 @@ USING DEVICE NODES
by sysfs counterparts. Using the commands in aoetools insulates by sysfs counterparts. Using the commands in aoetools insulates
users from these implementation details. users from these implementation details.
The block devices are named like this: The block devices are named like this::
e{shelf}.{slot} e{shelf}.{slot}
e{shelf}.{slot}p{part} e{shelf}.{slot}p{part}
@ -64,7 +69,8 @@ USING DEVICE NODES
first shelf (shelf address zero). That's the whole disk. The first first shelf (shelf address zero). That's the whole disk. The first
partition on that disk would be "e0.2p1". partition on that disk would be "e0.2p1".
USING SYSFS Using sysfs
===========
Each aoe block device in /sys/block has the extra attributes of Each aoe block device in /sys/block has the extra attributes of
state, mac, and netif. The state attribute is "up" when the device state, mac, and netif. The state attribute is "up" when the device
@ -78,29 +84,29 @@ USING SYSFS
There is a script in this directory that formats this information in There is a script in this directory that formats this information in
a convenient way. Users with aoetools should use the aoe-stat a convenient way. Users with aoetools should use the aoe-stat
command. command::
root@makki root# sh Documentation/aoe/status.sh root@makki root# sh Documentation/aoe/status.sh
e10.0 eth3 up e10.0 eth3 up
e10.1 eth3 up e10.1 eth3 up
e10.2 eth3 up e10.2 eth3 up
e10.3 eth3 up e10.3 eth3 up
e10.4 eth3 up e10.4 eth3 up
e10.5 eth3 up e10.5 eth3 up
e10.6 eth3 up e10.6 eth3 up
e10.7 eth3 up e10.7 eth3 up
e10.8 eth3 up e10.8 eth3 up
e10.9 eth3 up e10.9 eth3 up
e4.0 eth1 up e4.0 eth1 up
e4.1 eth1 up e4.1 eth1 up
e4.2 eth1 up e4.2 eth1 up
e4.3 eth1 up e4.3 eth1 up
e4.4 eth1 up e4.4 eth1 up
e4.5 eth1 up e4.5 eth1 up
e4.6 eth1 up e4.6 eth1 up
e4.7 eth1 up e4.7 eth1 up
e4.8 eth1 up e4.8 eth1 up
e4.9 eth1 up e4.9 eth1 up
Use /sys/module/aoe/parameters/aoe_iflist (or better, the driver Use /sys/module/aoe/parameters/aoe_iflist (or better, the driver
option discussed below) instead of /dev/etherd/interfaces to limit option discussed below) instead of /dev/etherd/interfaces to limit
@ -113,12 +119,13 @@ USING SYSFS
for this purpose. You can also directly use the for this purpose. You can also directly use the
/dev/etherd/discover special file described above. /dev/etherd/discover special file described above.
DRIVER OPTIONS Driver Options
==============
There is a boot option for the built-in aoe driver and a There is a boot option for the built-in aoe driver and a
corresponding module parameter, aoe_iflist. Without this option, corresponding module parameter, aoe_iflist. Without this option,
all network interfaces may be used for ATA over Ethernet. Here is a all network interfaces may be used for ATA over Ethernet. Here is a
usage example for the module parameter. usage example for the module parameter::
modprobe aoe_iflist="eth1 eth3" modprobe aoe_iflist="eth1 eth3"

23
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@ -0,0 +1,23 @@
Example of udev rules
---------------------
.. include:: udev.txt
:literal:
Example of udev install rules script
------------------------------------
.. literalinclude:: udev-install.sh
:language: shell
Example script to get status
----------------------------
.. literalinclude:: status.sh
:language: shell
Example of AoE autoload script
------------------------------
.. literalinclude:: autoload.sh
:language: shell

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@ -0,0 +1,19 @@
:orphan:
=======================
ATA over Ethernet (AoE)
=======================
.. toctree::
:maxdepth: 1
aoe
todo
examples
.. only:: subproject and html
Indices
=======
* :ref:`genindex`

3
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@ -1,3 +1,6 @@
TODO
====
There is a potential for deadlock when allocating a struct sk_buff for There is a potential for deadlock when allocating a struct sk_buff for
data that needs to be written out to aoe storage. If the data is data that needs to be written out to aoe storage. If the data is
being written from a dirty page in order to free that page, and if being written from a dirty page in order to free that page, and if

2
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@ -11,7 +11,7 @@
# udev_rules="/etc/udev/rules.d/" # udev_rules="/etc/udev/rules.d/"
# bash# ls /etc/udev/rules.d/ # bash# ls /etc/udev/rules.d/
# 10-wacom.rules 50-udev.rules # 10-wacom.rules 50-udev.rules
# bash# cp /path/to/linux-2.6.xx/Documentation/aoe/udev.txt \ # bash# cp /path/to/linux/Documentation/aoe/udev.txt \
# /etc/udev/rules.d/60-aoe.rules # /etc/udev/rules.d/60-aoe.rules
# #

2
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@ -1,4 +1,4 @@
Too many problems poped up because of unnoticed misaligned memory access in Too many problems popped up because of unnoticed misaligned memory access in
kernel code lately. Therefore the alignment fixup is now unconditionally kernel code lately. Therefore the alignment fixup is now unconditionally
configured in for SA11x0 based targets. According to Alan Cox, this is a configured in for SA11x0 based targets. According to Alan Cox, this is a
bad idea to configure it out, but Russell King has some good reasons for bad idea to configure it out, but Russell King has some good reasons for

2
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@ -1,3 +1,5 @@
:orphan:
======================== ========================
STM32 ARM Linux Overview STM32 ARM Linux Overview
======================== ========================

2
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@ -1,3 +1,5 @@
:orphan:
STM32F429 Overview STM32F429 Overview
================== ==================

2
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@ -1,3 +1,5 @@
:orphan:
STM32F746 Overview STM32F746 Overview
================== ==================

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STM32F769 Overview STM32F769 Overview
================== ==================

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STM32H743 Overview STM32H743 Overview
================== ==================

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STM32MP157 Overview STM32MP157 Overview
=================== ===================

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===========
ACPI Tables ACPI Tables
----------- ===========
The expectations of individual ACPI tables are discussed in the list that The expectations of individual ACPI tables are discussed in the list that
follows. follows.
@ -11,54 +13,71 @@ outside of the UEFI Forum (see Section 5.2.6 of the specification).
For ACPI on arm64, tables also fall into the following categories: For ACPI on arm64, tables also fall into the following categories:
-- Required: DSDT, FADT, GTDT, MADT, MCFG, RSDP, SPCR, XSDT - Required: DSDT, FADT, GTDT, MADT, MCFG, RSDP, SPCR, XSDT
-- Recommended: BERT, EINJ, ERST, HEST, PCCT, SSDT - Recommended: BERT, EINJ, ERST, HEST, PCCT, SSDT
-- Optional: BGRT, CPEP, CSRT, DBG2, DRTM, ECDT, FACS, FPDT, IORT, - Optional: BGRT, CPEP, CSRT, DBG2, DRTM, ECDT, FACS, FPDT, IORT,
MCHI, MPST, MSCT, NFIT, PMTT, RASF, SBST, SLIT, SPMI, SRAT, STAO, MCHI, MPST, MSCT, NFIT, PMTT, RASF, SBST, SLIT, SPMI, SRAT, STAO,
TCPA, TPM2, UEFI, XENV TCPA, TPM2, UEFI, XENV
-- Not supported: BOOT, DBGP, DMAR, ETDT, HPET, IBFT, IVRS, LPIT, - Not supported: BOOT, DBGP, DMAR, ETDT, HPET, IBFT, IVRS, LPIT,
MSDM, OEMx, PSDT, RSDT, SLIC, WAET, WDAT, WDRT, WPBT MSDM, OEMx, PSDT, RSDT, SLIC, WAET, WDAT, WDRT, WPBT
====== ========================================================================
Table Usage for ARMv8 Linux Table Usage for ARMv8 Linux
----- ---------------------------------------------------------------- ====== ========================================================================
BERT Section 18.3 (signature == "BERT") BERT Section 18.3 (signature == "BERT")
== Boot Error Record Table ==
**Boot Error Record Table**
Must be supplied if RAS support is provided by the platform. It Must be supplied if RAS support is provided by the platform. It
is recommended this table be supplied. is recommended this table be supplied.
BOOT Signature Reserved (signature == "BOOT") BOOT Signature Reserved (signature == "BOOT")
== simple BOOT flag table ==
**simple BOOT flag table**
Microsoft only table, will not be supported. Microsoft only table, will not be supported.
BGRT Section 5.2.22 (signature == "BGRT") BGRT Section 5.2.22 (signature == "BGRT")
== Boot Graphics Resource Table ==
**Boot Graphics Resource Table**
Optional, not currently supported, with no real use-case for an Optional, not currently supported, with no real use-case for an
ARM server. ARM server.
CPEP Section 5.2.18 (signature == "CPEP") CPEP Section 5.2.18 (signature == "CPEP")
== Corrected Platform Error Polling table ==
**Corrected Platform Error Polling table**
Optional, not currently supported, and not recommended until such Optional, not currently supported, and not recommended until such
time as ARM-compatible hardware is available, and the specification time as ARM-compatible hardware is available, and the specification
suitably modified. suitably modified.
CSRT Signature Reserved (signature == "CSRT") CSRT Signature Reserved (signature == "CSRT")
== Core System Resources Table ==
**Core System Resources Table**
Optional, not currently supported. Optional, not currently supported.
DBG2 Signature Reserved (signature == "DBG2") DBG2 Signature Reserved (signature == "DBG2")
== DeBuG port table 2 ==
**DeBuG port table 2**
License has changed and should be usable. Optional if used instead License has changed and should be usable. Optional if used instead
of earlycon=<device> on the command line. of earlycon=<device> on the command line.
DBGP Signature Reserved (signature == "DBGP") DBGP Signature Reserved (signature == "DBGP")
== DeBuG Port table ==
**DeBuG Port table**
Microsoft only table, will not be supported. Microsoft only table, will not be supported.
DSDT Section 5.2.11.1 (signature == "DSDT") DSDT Section 5.2.11.1 (signature == "DSDT")
== Differentiated System Description Table ==
**Differentiated System Description Table**
A DSDT is required; see also SSDT. A DSDT is required; see also SSDT.
ACPI tables contain only one DSDT but can contain one or more SSDTs, ACPI tables contain only one DSDT but can contain one or more SSDTs,
@ -66,22 +85,30 @@ DSDT Section 5.2.11.1 (signature == "DSDT")
but cannot modify or replace anything in the DSDT. but cannot modify or replace anything in the DSDT.
DMAR Signature Reserved (signature == "DMAR") DMAR Signature Reserved (signature == "DMAR")
== DMA Remapping table ==
**DMA Remapping table**
x86 only table, will not be supported. x86 only table, will not be supported.
DRTM Signature Reserved (signature == "DRTM") DRTM Signature Reserved (signature == "DRTM")
== Dynamic Root of Trust for Measurement table ==
**Dynamic Root of Trust for Measurement table**
Optional, not currently supported. Optional, not currently supported.
ECDT Section 5.2.16 (signature == "ECDT") ECDT Section 5.2.16 (signature == "ECDT")
== Embedded Controller Description Table ==
**Embedded Controller Description Table**
Optional, not currently supported, but could be used on ARM if and Optional, not currently supported, but could be used on ARM if and
only if one uses the GPE_BIT field to represent an IRQ number, since only if one uses the GPE_BIT field to represent an IRQ number, since
there are no GPE blocks defined in hardware reduced mode. This would there are no GPE blocks defined in hardware reduced mode. This would
need to be modified in the ACPI specification. need to be modified in the ACPI specification.
EINJ Section 18.6 (signature == "EINJ") EINJ Section 18.6 (signature == "EINJ")
== Error Injection table ==
**Error Injection table**
This table is very useful for testing platform response to error This table is very useful for testing platform response to error
conditions; it allows one to inject an error into the system as conditions; it allows one to inject an error into the system as
if it had actually occurred. However, this table should not be if it had actually occurred. However, this table should not be
@ -89,27 +116,35 @@ EINJ Section 18.6 (signature == "EINJ")
and executed with the ACPICA tools only during testing. and executed with the ACPICA tools only during testing.
ERST Section 18.5 (signature == "ERST") ERST Section 18.5 (signature == "ERST")
== Error Record Serialization Table ==
**Error Record Serialization Table**
On a platform supports RAS, this table must be supplied if it is not On a platform supports RAS, this table must be supplied if it is not
UEFI-based; if it is UEFI-based, this table may be supplied. When this UEFI-based; if it is UEFI-based, this table may be supplied. When this
table is not present, UEFI run time service will be utilized to save table is not present, UEFI run time service will be utilized to save
and retrieve hardware error information to and from a persistent store. and retrieve hardware error information to and from a persistent store.
ETDT Signature Reserved (signature == "ETDT") ETDT Signature Reserved (signature == "ETDT")
== Event Timer Description Table ==
**Event Timer Description Table**
Obsolete table, will not be supported. Obsolete table, will not be supported.
FACS Section 5.2.10 (signature == "FACS") FACS Section 5.2.10 (signature == "FACS")
== Firmware ACPI Control Structure ==
**Firmware ACPI Control Structure**
It is unlikely that this table will be terribly useful. If it is It is unlikely that this table will be terribly useful. If it is
provided, the Global Lock will NOT be used since it is not part of provided, the Global Lock will NOT be used since it is not part of
the hardware reduced profile, and only 64-bit address fields will the hardware reduced profile, and only 64-bit address fields will
be considered valid. be considered valid.
FADT Section 5.2.9 (signature == "FACP") FADT Section 5.2.9 (signature == "FACP")
== Fixed ACPI Description Table ==
**Fixed ACPI Description Table**
Required for arm64. Required for arm64.
The HW_REDUCED_ACPI flag must be set. All of the fields that are The HW_REDUCED_ACPI flag must be set. All of the fields that are
to be ignored when HW_REDUCED_ACPI is set are expected to be set to to be ignored when HW_REDUCED_ACPI is set are expected to be set to
zero. zero.
@ -118,22 +153,28 @@ FADT Section 5.2.9 (signature == "FACP")
used, not FIRMWARE_CTRL. used, not FIRMWARE_CTRL.
If PSCI is used (as is recommended), make sure that ARM_BOOT_ARCH is If PSCI is used (as is recommended), make sure that ARM_BOOT_ARCH is
filled in properly -- that the PSCI_COMPLIANT flag is set and that filled in properly - that the PSCI_COMPLIANT flag is set and that
PSCI_USE_HVC is set or unset as needed (see table 5-37). PSCI_USE_HVC is set or unset as needed (see table 5-37).
For the DSDT that is also required, the X_DSDT field is to be used, For the DSDT that is also required, the X_DSDT field is to be used,
not the DSDT field. not the DSDT field.
FPDT Section 5.2.23 (signature == "FPDT") FPDT Section 5.2.23 (signature == "FPDT")
== Firmware Performance Data Table ==
**Firmware Performance Data Table**
Optional, not currently supported. Optional, not currently supported.
GTDT Section 5.2.24 (signature == "GTDT") GTDT Section 5.2.24 (signature == "GTDT")
== Generic Timer Description Table ==
**Generic Timer Description Table**
Required for arm64. Required for arm64.
HEST Section 18.3.2 (signature == "HEST") HEST Section 18.3.2 (signature == "HEST")
== Hardware Error Source Table ==
**Hardware Error Source Table**
ARM-specific error sources have been defined; please use those or the ARM-specific error sources have been defined; please use those or the
PCI types such as type 6 (AER Root Port), 7 (AER Endpoint), or 8 (AER PCI types such as type 6 (AER Root Port), 7 (AER Endpoint), or 8 (AER
Bridge), or use type 9 (Generic Hardware Error Source). Firmware first Bridge), or use type 9 (Generic Hardware Error Source). Firmware first
@ -144,122 +185,174 @@ HEST Section 18.3.2 (signature == "HEST")
is recommended this table be supplied. is recommended this table be supplied.
HPET Signature Reserved (signature == "HPET") HPET Signature Reserved (signature == "HPET")
== High Precision Event timer Table ==
**High Precision Event timer Table**
x86 only table, will not be supported. x86 only table, will not be supported.
IBFT Signature Reserved (signature == "IBFT") IBFT Signature Reserved (signature == "IBFT")
== iSCSI Boot Firmware Table ==
**iSCSI Boot Firmware Table**
Microsoft defined table, support TBD. Microsoft defined table, support TBD.
IORT Signature Reserved (signature == "IORT") IORT Signature Reserved (signature == "IORT")
== Input Output Remapping Table ==
**Input Output Remapping Table**
arm64 only table, required in order to describe IO topology, SMMUs, arm64 only table, required in order to describe IO topology, SMMUs,
and GIC ITSs, and how those various components are connected together, and GIC ITSs, and how those various components are connected together,
such as identifying which components are behind which SMMUs/ITSs. such as identifying which components are behind which SMMUs/ITSs.
This table will only be required on certain SBSA platforms (e.g., This table will only be required on certain SBSA platforms (e.g.,
when using GICv3-ITS and an SMMU); on SBSA Level 0 platforms, it when using GICv3-ITS and an SMMU); on SBSA Level 0 platforms, it
remains optional. remains optional.
IVRS Signature Reserved (signature == "IVRS") IVRS Signature Reserved (signature == "IVRS")
== I/O Virtualization Reporting Structure ==
**I/O Virtualization Reporting Structure**
x86_64 (AMD) only table, will not be supported. x86_64 (AMD) only table, will not be supported.
LPIT Signature Reserved (signature == "LPIT") LPIT Signature Reserved (signature == "LPIT")
== Low Power Idle Table ==
**Low Power Idle Table**
x86 only table as of ACPI 5.1; starting with ACPI 6.0, processor x86 only table as of ACPI 5.1; starting with ACPI 6.0, processor
descriptions and power states on ARM platforms should use the DSDT descriptions and power states on ARM platforms should use the DSDT
and define processor container devices (_HID ACPI0010, Section 8.4, and define processor container devices (_HID ACPI0010, Section 8.4,
and more specifically 8.4.3 and and 8.4.4). and more specifically 8.4.3 and and 8.4.4).
MADT Section 5.2.12 (signature == "APIC") MADT Section 5.2.12 (signature == "APIC")
== Multiple APIC Description Table ==
**Multiple APIC Description Table**
Required for arm64. Only the GIC interrupt controller structures Required for arm64. Only the GIC interrupt controller structures
should be used (types 0xA - 0xF). should be used (types 0xA - 0xF).
MCFG Signature Reserved (signature == "MCFG") MCFG Signature Reserved (signature == "MCFG")
== Memory-mapped ConFiGuration space ==
**Memory-mapped ConFiGuration space**
If the platform supports PCI/PCIe, an MCFG table is required. If the platform supports PCI/PCIe, an MCFG table is required.
MCHI Signature Reserved (signature == "MCHI") MCHI Signature Reserved (signature == "MCHI")
== Management Controller Host Interface table ==
**Management Controller Host Interface table**
Optional, not currently supported. Optional, not currently supported.
MPST Section 5.2.21 (signature == "MPST") MPST Section 5.2.21 (signature == "MPST")
== Memory Power State Table ==
**Memory Power State Table**
Optional, not currently supported. Optional, not currently supported.
MSCT Section 5.2.19 (signature == "MSCT") MSCT Section 5.2.19 (signature == "MSCT")
== Maximum System Characteristic Table ==
**Maximum System Characteristic Table**
Optional, not currently supported. Optional, not currently supported.
MSDM Signature Reserved (signature == "MSDM") MSDM Signature Reserved (signature == "MSDM")
== Microsoft Data Management table ==
**Microsoft Data Management table**
Microsoft only table, will not be supported. Microsoft only table, will not be supported.
NFIT Section 5.2.25 (signature == "NFIT") NFIT Section 5.2.25 (signature == "NFIT")
== NVDIMM Firmware Interface Table ==
**NVDIMM Firmware Interface Table**
Optional, not currently supported. Optional, not currently supported.
OEMx Signature of "OEMx" only OEMx Signature of "OEMx" only
== OEM Specific Tables ==
**OEM Specific Tables**
All tables starting with a signature of "OEM" are reserved for OEM All tables starting with a signature of "OEM" are reserved for OEM
use. Since these are not meant to be of general use but are limited use. Since these are not meant to be of general use but are limited
to very specific end users, they are not recommended for use and are to very specific end users, they are not recommended for use and are
not supported by the kernel for arm64. not supported by the kernel for arm64.
PCCT Section 14.1 (signature == "PCCT) PCCT Section 14.1 (signature == "PCCT)
== Platform Communications Channel Table ==
**Platform Communications Channel Table**
Recommend for use on arm64; use of PCC is recommended when using CPPC Recommend for use on arm64; use of PCC is recommended when using CPPC
to control performance and power for platform processors. to control performance and power for platform processors.
PMTT Section 5.2.21.12 (signature == "PMTT") PMTT Section 5.2.21.12 (signature == "PMTT")
== Platform Memory Topology Table ==
**Platform Memory Topology Table**
Optional, not currently supported. Optional, not currently supported.
PSDT Section 5.2.11.3 (signature == "PSDT") PSDT Section 5.2.11.3 (signature == "PSDT")
== Persistent System Description Table ==
**Persistent System Description Table**
Obsolete table, will not be supported. Obsolete table, will not be supported.
RASF Section 5.2.20 (signature == "RASF") RASF Section 5.2.20 (signature == "RASF")
== RAS Feature table ==
**RAS Feature table**
Optional, not currently supported. Optional, not currently supported.
RSDP Section 5.2.5 (signature == "RSD PTR") RSDP Section 5.2.5 (signature == "RSD PTR")
== Root System Description PoinTeR ==
**Root System Description PoinTeR**
Required for arm64. Required for arm64.
RSDT Section 5.2.7 (signature == "RSDT") RSDT Section 5.2.7 (signature == "RSDT")
== Root System Description Table ==
**Root System Description Table**
Since this table can only provide 32-bit addresses, it is deprecated Since this table can only provide 32-bit addresses, it is deprecated
on arm64, and will not be used. If provided, it will be ignored. on arm64, and will not be used. If provided, it will be ignored.
SBST Section 5.2.14 (signature == "SBST") SBST Section 5.2.14 (signature == "SBST")
== Smart Battery Subsystem Table ==
**Smart Battery Subsystem Table**
Optional, not currently supported. Optional, not currently supported.
SLIC Signature Reserved (signature == "SLIC") SLIC Signature Reserved (signature == "SLIC")
== Software LIcensing table ==
**Software LIcensing table**
Microsoft only table, will not be supported. Microsoft only table, will not be supported.
SLIT Section 5.2.17 (signature == "SLIT") SLIT Section 5.2.17 (signature == "SLIT")
== System Locality distance Information Table ==
**System Locality distance Information Table**
Optional in general, but required for NUMA systems. Optional in general, but required for NUMA systems.
SPCR Signature Reserved (signature == "SPCR") SPCR Signature Reserved (signature == "SPCR")
== Serial Port Console Redirection table ==
**Serial Port Console Redirection table**
Required for arm64. Required for arm64.
SPMI Signature Reserved (signature == "SPMI") SPMI Signature Reserved (signature == "SPMI")
== Server Platform Management Interface table ==
**Server Platform Management Interface table**
Optional, not currently supported. Optional, not currently supported.
SRAT Section 5.2.16 (signature == "SRAT") SRAT Section 5.2.16 (signature == "SRAT")
== System Resource Affinity Table ==
**System Resource Affinity Table**
Optional, but if used, only the GICC Affinity structures are read. Optional, but if used, only the GICC Affinity structures are read.
To support arm64 NUMA, this table is required. To support arm64 NUMA, this table is required.
SSDT Section 5.2.11.2 (signature == "SSDT") SSDT Section 5.2.11.2 (signature == "SSDT")
== Secondary System Description Table ==
**Secondary System Description Table**
These tables are a continuation of the DSDT; these are recommended These tables are a continuation of the DSDT; these are recommended
for use with devices that can be added to a running system, but can for use with devices that can be added to a running system, but can
also serve the purpose of dividing up device descriptions into more also serve the purpose of dividing up device descriptions into more
@ -272,49 +365,69 @@ SSDT Section 5.2.11.2 (signature == "SSDT")
one DSDT but can contain many SSDTs. one DSDT but can contain many SSDTs.
STAO Signature Reserved (signature == "STAO") STAO Signature Reserved (signature == "STAO")
== _STA Override table ==
**_STA Override table**
Optional, but only necessary in virtualized environments in order to Optional, but only necessary in virtualized environments in order to
hide devices from guest OSs. hide devices from guest OSs.
TCPA Signature Reserved (signature == "TCPA") TCPA Signature Reserved (signature == "TCPA")
== Trusted Computing Platform Alliance table ==
**Trusted Computing Platform Alliance table**
Optional, not currently supported, and may need changes to fully Optional, not currently supported, and may need changes to fully
interoperate with arm64. interoperate with arm64.
TPM2 Signature Reserved (signature == "TPM2") TPM2 Signature Reserved (signature == "TPM2")
== Trusted Platform Module 2 table ==
**Trusted Platform Module 2 table**
Optional, not currently supported, and may need changes to fully Optional, not currently supported, and may need changes to fully
interoperate with arm64. interoperate with arm64.
UEFI Signature Reserved (signature == "UEFI") UEFI Signature Reserved (signature == "UEFI")
== UEFI ACPI data table ==
**UEFI ACPI data table**
Optional, not currently supported. No known use case for arm64, Optional, not currently supported. No known use case for arm64,
at present. at present.
WAET Signature Reserved (signature == "WAET") WAET Signature Reserved (signature == "WAET")
== Windows ACPI Emulated devices Table ==
**Windows ACPI Emulated devices Table**
Microsoft only table, will not be supported. Microsoft only table, will not be supported.
WDAT Signature Reserved (signature == "WDAT") WDAT Signature Reserved (signature == "WDAT")
== Watch Dog Action Table ==
**Watch Dog Action Table**
Microsoft only table, will not be supported. Microsoft only table, will not be supported.
WDRT Signature Reserved (signature == "WDRT") WDRT Signature Reserved (signature == "WDRT")
== Watch Dog Resource Table ==
**Watch Dog Resource Table**
Microsoft only table, will not be supported. Microsoft only table, will not be supported.
WPBT Signature Reserved (signature == "WPBT") WPBT Signature Reserved (signature == "WPBT")
== Windows Platform Binary Table ==
**Windows Platform Binary Table**
Microsoft only table, will not be supported. Microsoft only table, will not be supported.
XENV Signature Reserved (signature == "XENV") XENV Signature Reserved (signature == "XENV")
== Xen project table ==
**Xen project table**
Optional, used only by Xen at present. Optional, used only by Xen at present.
XSDT Section 5.2.8 (signature == "XSDT") XSDT Section 5.2.8 (signature == "XSDT")
== eXtended System Description Table ==
Required for arm64.
**eXtended System Description Table**
Required for arm64.
====== ========================================================================
ACPI Objects ACPI Objects
------------ ------------
@ -323,10 +436,11 @@ shown in the list that follows; any object not explicitly mentioned below
should be used as needed for a particular platform or particular subsystem, should be used as needed for a particular platform or particular subsystem,
such as power management or PCI. such as power management or PCI.
===== ================ ========================================================
Name Section Usage for ARMv8 Linux Name Section Usage for ARMv8 Linux
---- ------------ ------------------------------------------------- ===== ================ ========================================================
_CCA 6.2.17 This method must be defined for all bus masters _CCA 6.2.17 This method must be defined for all bus masters
on arm64 -- there are no assumptions made about on arm64 - there are no assumptions made about
whether such devices are cache coherent or not. whether such devices are cache coherent or not.
The _CCA value is inherited by all descendants of The _CCA value is inherited by all descendants of
these devices so it does not need to be repeated. these devices so it does not need to be repeated.
@ -422,8 +536,8 @@ _OSC 6.2.11 This method can be a global method in ACPI (i.e.,
by the kernel community, then register it with the by the kernel community, then register it with the
UEFI Forum. UEFI Forum.
\_OSI 5.7.2 Deprecated on ARM64. As far as ACPI firmware is \_OSI 5.7.2 Deprecated on ARM64. As far as ACPI firmware is
concerned, _OSI is not to be used to determine what concerned, _OSI is not to be used to determine what
sort of system is being used or what functionality sort of system is being used or what functionality
is provided. The _OSC method is to be used instead. is provided. The _OSC method is to be used instead.
@ -447,7 +561,7 @@ _PSx 7.3.2-5 Use as needed; power management specific. If _PS0 is
usage, change them in these methods. usage, change them in these methods.
_RDI 8.4.4.4 Recommended for use with processor definitions (_HID _RDI 8.4.4.4 Recommended for use with processor definitions (_HID
ACPI0010) on arm64. This should only be used in ACPI0010) on arm64. This should only be used in
conjunction with _LPI. conjunction with _LPI.
\_REV 5.7.4 Always returns the latest version of ACPI supported. \_REV 5.7.4 Always returns the latest version of ACPI supported.
@ -476,6 +590,7 @@ _SWS 7.4.3 Use as needed; power management specific; this may
_UID 6.1.12 Recommended for distinguishing devices of the same _UID 6.1.12 Recommended for distinguishing devices of the same
class; define it if at all possible. class; define it if at all possible.
===== ================ ========================================================
@ -488,7 +603,7 @@ platforms, ACPI events must be signaled differently.
There are two options: GPIO-signaled interrupts (Section 5.6.5), and There are two options: GPIO-signaled interrupts (Section 5.6.5), and
interrupt-signaled events (Section 5.6.9). Interrupt-signaled events are a interrupt-signaled events (Section 5.6.9). Interrupt-signaled events are a
new feature in the ACPI 6.1 specification. Either -- or both -- can be used new feature in the ACPI 6.1 specification. Either - or both - can be used
on a given platform, and which to use may be dependent of limitations in any on a given platform, and which to use may be dependent of limitations in any
given SoC. If possible, interrupt-signaled events are recommended. given SoC. If possible, interrupt-signaled events are recommended.
@ -564,39 +679,40 @@ supported.
The following classes of objects are not supported: The following classes of objects are not supported:
-- Section 9.2: ambient light sensor devices - Section 9.2: ambient light sensor devices
-- Section 9.3: battery devices - Section 9.3: battery devices
-- Section 9.4: lids (e.g., laptop lids) - Section 9.4: lids (e.g., laptop lids)
-- Section 9.8.2: IDE controllers - Section 9.8.2: IDE controllers
-- Section 9.9: floppy controllers - Section 9.9: floppy controllers
-- Section 9.10: GPE block devices - Section 9.10: GPE block devices
-- Section 9.15: PC/AT RTC/CMOS devices - Section 9.15: PC/AT RTC/CMOS devices
-- Section 9.16: user presence detection devices - Section 9.16: user presence detection devices
-- Section 9.17: I/O APIC devices; all GICs must be enumerable via MADT - Section 9.17: I/O APIC devices; all GICs must be enumerable via MADT
-- Section 9.18: time and alarm devices (see 9.15) - Section 9.18: time and alarm devices (see 9.15)
-- Section 10: power source and power meter devices - Section 10: power source and power meter devices
-- Section 11: thermal management - Section 11: thermal management
-- Section 12: embedded controllers interface - Section 12: embedded controllers interface
-- Section 13: SMBus interfaces - Section 13: SMBus interfaces
This also means that there is no support for the following objects: This also means that there is no support for the following objects:
==== =========================== ==== ==========
Name Section Name Section Name Section Name Section
---- ------------ ---- ------------ ==== =========================== ==== ==========
_ALC 9.3.4 _FDM 9.10.3 _ALC 9.3.4 _FDM 9.10.3
_ALI 9.3.2 _FIX 6.2.7 _ALI 9.3.2 _FIX 6.2.7
_ALP 9.3.6 _GAI 10.4.5 _ALP 9.3.6 _GAI 10.4.5
@ -619,4 +735,4 @@ _DCK 6.5.2 _UPD 9.16.1
_EC 12.12 _UPP 9.16.2 _EC 12.12 _UPP 9.16.2
_FDE 9.10.1 _WPC 10.5.2 _FDE 9.10.1 _WPC 10.5.2
_FDI 9.10.2 _WPP 10.5.3 _FDI 9.10.2 _WPP 10.5.3
==== =========================== ==== ==========

155
Documentation/arm64/arm-acpi.txt → Documentation/arm64/arm-acpi.rst
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@ -1,5 +1,7 @@
=====================
ACPI on ARMv8 Servers ACPI on ARMv8 Servers
--------------------- =====================
ACPI can be used for ARMv8 general purpose servers designed to follow ACPI can be used for ARMv8 general purpose servers designed to follow
the ARM SBSA (Server Base System Architecture) [0] and SBBR (Server the ARM SBSA (Server Base System Architecture) [0] and SBBR (Server
Base Boot Requirements) [1] specifications. Please note that the SBBR Base Boot Requirements) [1] specifications. Please note that the SBBR
@ -34,28 +36,28 @@ of the summary text almost directly, to be honest.
The short form of the rationale for ACPI on ARM is: The short form of the rationale for ACPI on ARM is:
-- ACPI’s byte code (AML) allows the platform to encode hardware behavior, - ACPI’s byte code (AML) allows the platform to encode hardware behavior,
while DT explicitly does not support this. For hardware vendors, being while DT explicitly does not support this. For hardware vendors, being
able to encode behavior is a key tool used in supporting operating able to encode behavior is a key tool used in supporting operating
system releases on new hardware. system releases on new hardware.
-- ACPI’s OSPM defines a power management model that constrains what the - ACPI’s OSPM defines a power management model that constrains what the
platform is allowed to do into a specific model, while still providing platform is allowed to do into a specific model, while still providing
flexibility in hardware design. flexibility in hardware design.
-- In the enterprise server environment, ACPI has established bindings (such - In the enterprise server environment, ACPI has established bindings (such
as for RAS) which are currently used in production systems. DT does not. as for RAS) which are currently used in production systems. DT does not.
Such bindings could be defined in DT at some point, but doing so means ARM Such bindings could be defined in DT at some point, but doing so means ARM
and x86 would end up using completely different code paths in both firmware and x86 would end up using completely different code paths in both firmware
and the kernel. and the kernel.
-- Choosing a single interface to describe the abstraction between a platform - Choosing a single interface to describe the abstraction between a platform
and an OS is important. Hardware vendors would not be required to implement and an OS is important. Hardware vendors would not be required to implement
both DT and ACPI if they want to support multiple operating systems. And, both DT and ACPI if they want to support multiple operating systems. And,
agreeing on a single interface instead of being fragmented into per OS agreeing on a single interface instead of being fragmented into per OS
interfaces makes for better interoperability overall. interfaces makes for better interoperability overall.
-- The new ACPI governance process works well and Linux is now at the same - The new ACPI governance process works well and Linux is now at the same
table as hardware vendors and other OS vendors. In fact, there is no table as hardware vendors and other OS vendors. In fact, there is no
longer any reason to feel that ACPI only belongs to Windows or that longer any reason to feel that ACPI only belongs to Windows or that
Linux is in any way secondary to Microsoft in this arena. The move of Linux is in any way secondary to Microsoft in this arena. The move of
@ -169,31 +171,31 @@ For the ACPI core to operate properly, and in turn provide the information
the kernel needs to configure devices, it expects to find the following the kernel needs to configure devices, it expects to find the following
tables (all section numbers refer to the ACPI 6.1 specification): tables (all section numbers refer to the ACPI 6.1 specification):
-- RSDP (Root System Description Pointer), section 5.2.5 - RSDP (Root System Description Pointer), section 5.2.5
-- XSDT (eXtended System Description Table), section 5.2.8 - XSDT (eXtended System Description Table), section 5.2.8
-- FADT (Fixed ACPI Description Table), section 5.2.9 - FADT (Fixed ACPI Description Table), section 5.2.9
-- DSDT (Differentiated System Description Table), section - DSDT (Differentiated System Description Table), section
5.2.11.1 5.2.11.1
-- MADT (Multiple APIC Description Table), section 5.2.12 - MADT (Multiple APIC Description Table), section 5.2.12
-- GTDT (Generic Timer Description Table), section 5.2.24 - GTDT (Generic Timer Description Table), section 5.2.24
-- If PCI is supported, the MCFG (Memory mapped ConFiGuration - If PCI is supported, the MCFG (Memory mapped ConFiGuration
Table), section 5.2.6, specifically Table 5-31. Table), section 5.2.6, specifically Table 5-31.
-- If booting without a console=<device> kernel parameter is - If booting without a console=<device> kernel parameter is
supported, the SPCR (Serial Port Console Redirection table), supported, the SPCR (Serial Port Console Redirection table),
section 5.2.6, specifically Table 5-31. section 5.2.6, specifically Table 5-31.
-- If necessary to describe the I/O topology, SMMUs and GIC ITSs, - If necessary to describe the I/O topology, SMMUs and GIC ITSs,
the IORT (Input Output Remapping Table, section 5.2.6, specifically the IORT (Input Output Remapping Table, section 5.2.6, specifically
Table 5-31). Table 5-31).
-- If NUMA is supported, the SRAT (System Resource Affinity Table) - If NUMA is supported, the SRAT (System Resource Affinity Table)
and SLIT (System Locality distance Information Table), sections and SLIT (System Locality distance Information Table), sections
5.2.16 and 5.2.17, respectively. 5.2.16 and 5.2.17, respectively.
@ -269,9 +271,9 @@ describes how to define the structure of an object returned via _DSD, and
how specific data structures are defined by specific UUIDs. Linux should how specific data structures are defined by specific UUIDs. Linux should
only use the _DSD Device Properties UUID [5]: only use the _DSD Device Properties UUID [5]:
-- UUID: daffd814-6eba-4d8c-8a91-bc9bbf4aa301 - UUID: daffd814-6eba-4d8c-8a91-bc9bbf4aa301
-- http://www.uefi.org/sites/default/files/resources/_DSD-device-properties-UUID.pdf - http://www.uefi.org/sites/default/files/resources/_DSD-device-properties-UUID.pdf
The UEFI Forum provides a mechanism for registering device properties [4] The UEFI Forum provides a mechanism for registering device properties [4]
so that they may be used across all operating systems supporting ACPI. so that they may be used across all operating systems supporting ACPI.
@ -327,10 +329,10 @@ turning a device full off.
There are two options for using those Power Resources. They can: There are two options for using those Power Resources. They can:
-- be managed in a _PSx method which gets called on entry to power - be managed in a _PSx method which gets called on entry to power
state Dx. state Dx.
-- be declared separately as power resources with their own _ON and _OFF - be declared separately as power resources with their own _ON and _OFF
methods. They are then tied back to D-states for a particular device methods. They are then tied back to D-states for a particular device
via _PRx which specifies which power resources a device needs to be on via _PRx which specifies which power resources a device needs to be on
while in Dx. Kernel then tracks number of devices using a power resource while in Dx. Kernel then tracks number of devices using a power resource
@ -339,16 +341,16 @@ There are two options for using those Power Resources. They can:
The kernel ACPI code will also assume that the _PSx methods follow the normal The kernel ACPI code will also assume that the _PSx methods follow the normal
ACPI rules for such methods: ACPI rules for such methods:
-- If either _PS0 or _PS3 is implemented, then the other method must also - If either _PS0 or _PS3 is implemented, then the other method must also
be implemented. be implemented.
-- If a device requires usage or setup of a power resource when on, the ASL - If a device requires usage or setup of a power resource when on, the ASL
should organize that it is allocated/enabled using the _PS0 method. should organize that it is allocated/enabled using the _PS0 method.
-- Resources allocated or enabled in the _PS0 method should be disabled - Resources allocated or enabled in the _PS0 method should be disabled
or de-allocated in the _PS3 method. or de-allocated in the _PS3 method.
-- Firmware will leave the resources in a reasonable state before handing - Firmware will leave the resources in a reasonable state before handing
over control to the kernel. over control to the kernel.
Such code in _PSx methods will of course be very platform specific. But, Such code in _PSx methods will of course be very platform specific. But,
@ -394,52 +396,52 @@ else must be discovered by the driver probe function. Then, have the rest
of the driver operate off of the contents of that struct. Doing so should of the driver operate off of the contents of that struct. Doing so should
allow most divergence between ACPI and DT functionality to be kept local to allow most divergence between ACPI and DT functionality to be kept local to
the probe function instead of being scattered throughout the driver. For the probe function instead of being scattered throughout the driver. For
example: example::
static int device_probe_dt(struct platform_device *pdev) static int device_probe_dt(struct platform_device *pdev)
{ {
/* DT specific functionality */ /* DT specific functionality */
... ...
} }
static int device_probe_acpi(struct platform_device *pdev) static int device_probe_acpi(struct platform_device *pdev)
{ {
/* ACPI specific functionality */ /* ACPI specific functionality */
... ...
} }
static int device_probe(struct platform_device *pdev) static int device_probe(struct platform_device *pdev)
{ {
... ...
struct device_node node = pdev->dev.of_node; struct device_node node = pdev->dev.of_node;
... ...
if (node) if (node)
ret = device_probe_dt(pdev); ret = device_probe_dt(pdev);
else if (ACPI_HANDLE(&pdev->dev)) else if (ACPI_HANDLE(&pdev->dev))
ret = device_probe_acpi(pdev); ret = device_probe_acpi(pdev);
else else
/* other initialization */ /* other initialization */
... ...
/* Continue with any generic probe operations */ /* Continue with any generic probe operations */
... ...
} }
DO keep the MODULE_DEVICE_TABLE entries together in the driver to make it DO keep the MODULE_DEVICE_TABLE entries together in the driver to make it
clear the different names the driver is probed for, both from DT and from clear the different names the driver is probed for, both from DT and from
ACPI: ACPI::
static struct of_device_id virtio_mmio_match[] = { static struct of_device_id virtio_mmio_match[] = {
{ .compatible = "virtio,mmio", }, { .compatible = "virtio,mmio", },
{ } { }
}; };
MODULE_DEVICE_TABLE(of, virtio_mmio_match); MODULE_DEVICE_TABLE(of, virtio_mmio_match);
static const struct acpi_device_id virtio_mmio_acpi_match[] = { static const struct acpi_device_id virtio_mmio_acpi_match[] = {
{ "LNRO0005", }, { "LNRO0005", },
{ } { }
}; };
MODULE_DEVICE_TABLE(acpi, virtio_mmio_acpi_match); MODULE_DEVICE_TABLE(acpi, virtio_mmio_acpi_match);
ASWG ASWG
@ -471,7 +473,8 @@ Linux Code
Individual items specific to Linux on ARM, contained in the the Linux Individual items specific to Linux on ARM, contained in the the Linux
source code, are in the list that follows: source code, are in the list that follows:
ACPI_OS_NAME This macro defines the string to be returned when ACPI_OS_NAME
This macro defines the string to be returned when
an ACPI method invokes the _OS method. On ARM64 an ACPI method invokes the _OS method. On ARM64
systems, this macro will be "Linux" by default. systems, this macro will be "Linux" by default.
The command line parameter acpi_os=<string> The command line parameter acpi_os=<string>
@ -482,38 +485,44 @@ ACPI_OS_NAME This macro defines the string to be returned when
ACPI Objects ACPI Objects
------------ ------------
Detailed expectations for ACPI tables and object are listed in the file Detailed expectations for ACPI tables and object are listed in the file
Documentation/arm64/acpi_object_usage.txt. Documentation/arm64/acpi_object_usage.rst.
References References
---------- ----------
[0] http://silver.arm.com -- document ARM-DEN-0029, or newer [0] http://silver.arm.com
document ARM-DEN-0029, or newer:
"Server Base System Architecture", version 2.3, dated 27 Mar 2014 "Server Base System Architecture", version 2.3, dated 27 Mar 2014
[1] http://infocenter.arm.com/help/topic/com.arm.doc.den0044a/Server_Base_Boot_Requirements.pdf [1] http://infocenter.arm.com/help/topic/com.arm.doc.den0044a/Server_Base_Boot_Requirements.pdf
Document ARM-DEN-0044A, or newer: "Server Base Boot Requirements, System Document ARM-DEN-0044A, or newer: "Server Base Boot Requirements, System
Software on ARM Platforms", dated 16 Aug 2014 Software on ARM Platforms", dated 16 Aug 2014
[2] http://www.secretlab.ca/archives/151, 10 Jan 2015, Copyright (c) 2015, [2] http://www.secretlab.ca/archives/151,
10 Jan 2015, Copyright (c) 2015,
Linaro Ltd., written by Grant Likely. Linaro Ltd., written by Grant Likely.
[3] AMD ACPI for Seattle platform documentation: [3] AMD ACPI for Seattle platform documentation
http://amd-dev.wpengine.netdna-cdn.com/wordpress/media/2012/10/Seattle_ACPI_Guide.pdf http://amd-dev.wpengine.netdna-cdn.com/wordpress/media/2012/10/Seattle_ACPI_Guide.pdf
[4] http://www.uefi.org/acpi -- please see the link for the "ACPI _DSD Device
[4] http://www.uefi.org/acpi
please see the link for the "ACPI _DSD Device
Property Registry Instructions" Property Registry Instructions"
[5] http://www.uefi.org/acpi -- please see the link for the "_DSD (Device [5] http://www.uefi.org/acpi
please see the link for the "_DSD (Device
Specific Data) Implementation Guide" Specific Data) Implementation Guide"
[6] Kernel code for the unified device property interface can be found in [6] Kernel code for the unified device
property interface can be found in
include/linux/property.h and drivers/base/property.c. include/linux/property.h and drivers/base/property.c.
Authors Authors
------- -------
Al Stone <al.stone@linaro.org> - Al Stone <al.stone@linaro.org>
Graeme Gregory <graeme.gregory@linaro.org> - Graeme Gregory <graeme.gregory@linaro.org>
Hanjun Guo <hanjun.guo@linaro.org> - Hanjun Guo <hanjun.guo@linaro.org>
Grant Likely <grant.likely@linaro.org>, for the "Why ACPI on ARM?" section - Grant Likely <grant.likely@linaro.org>, for the "Why ACPI on ARM?" section

91
Documentation/arm64/booting.txt → Documentation/arm64/booting.rst
View File

@ -1,7 +1,9 @@
Booting AArch64 Linux =====================
===================== Booting AArch64 Linux
=====================
Author: Will Deacon <will.deacon@arm.com> Author: Will Deacon <will.deacon@arm.com>
Date : 07 September 2012 Date : 07 September 2012
This document is based on the ARM booting document by Russell King and This document is based on the ARM booting document by Russell King and
@ -12,7 +14,7 @@ The AArch64 exception model is made up of a number of exception levels
counterpart. EL2 is the hypervisor level and exists only in non-secure counterpart. EL2 is the hypervisor level and exists only in non-secure
mode. EL3 is the highest priority level and exists only in secure mode. mode. EL3 is the highest priority level and exists only in secure mode.
For the purposes of this document, we will use the term `boot loader' For the purposes of this document, we will use the term `boot loader`
simply to define all software that executes on the CPU(s) before control simply to define all software that executes on the CPU(s) before control
is passed to the Linux kernel. This may include secure monitor and is passed to the Linux kernel. This may include secure monitor and
hypervisor code, or it may just be a handful of instructions for hypervisor code, or it may just be a handful of instructions for
@ -70,7 +72,7 @@ Image target is available instead.
Requirement: MANDATORY Requirement: MANDATORY
The decompressed kernel image contains a 64-byte header as follows: The decompressed kernel image contains a 64-byte header as follows::
u32 code0; /* Executable code */ u32 code0; /* Executable code */
u32 code1; /* Executable code */ u32 code1; /* Executable code */
@ -103,19 +105,26 @@ Header notes:
- The flags field (introduced in v3.17) is a little-endian 64-bit field - The flags field (introduced in v3.17) is a little-endian 64-bit field
composed as follows: composed as follows:
Bit 0: Kernel endianness. 1 if BE, 0 if LE.
Bit 1-2: Kernel Page size. ============= ===============================================================
0 - Unspecified. Bit 0 Kernel endianness. 1 if BE, 0 if LE.
1 - 4K Bit 1-2 Kernel Page size.
2 - 16K
3 - 64K * 0 - Unspecified.
Bit 3: Kernel physical placement * 1 - 4K
0 - 2MB aligned base should be as close as possible * 2 - 16K
to the base of DRAM, since memory below it is not * 3 - 64K
accessible via the linear mapping Bit 3 Kernel physical placement
1 - 2MB aligned base may be anywhere in physical
memory 0
Bits 4-63: Reserved. 2MB aligned base should be as close as possible
to the base of DRAM, since memory below it is not
accessible via the linear mapping
1
2MB aligned base may be anywhere in physical
memory
Bits 4-63 Reserved.
============= ===============================================================
- When image_size is zero, a bootloader should attempt to keep as much - When image_size is zero, a bootloader should attempt to keep as much
memory as possible free for use by the kernel immediately after the memory as possible free for use by the kernel immediately after the
@ -147,19 +156,22 @@ Before jumping into the kernel, the following conditions must be met:
corrupted by bogus network packets or disk data. This will save corrupted by bogus network packets or disk data. This will save
you many hours of debug. you many hours of debug.
- Primary CPU general-purpose register settings - Primary CPU general-purpose register settings:
x0 = physical address of device tree blob (dtb) in system RAM.
x1 = 0 (reserved for future use) - x0 = physical address of device tree blob (dtb) in system RAM.
x2 = 0 (reserved for future use) - x1 = 0 (reserved for future use)
x3 = 0 (reserved for future use) - x2 = 0 (reserved for future use)
- x3 = 0 (reserved for future use)
- CPU mode - CPU mode
All forms of interrupts must be masked in PSTATE.DAIF (Debug, SError, All forms of interrupts must be masked in PSTATE.DAIF (Debug, SError,
IRQ and FIQ). IRQ and FIQ).
The CPU must be in either EL2 (RECOMMENDED in order to have access to The CPU must be in either EL2 (RECOMMENDED in order to have access to
the virtualisation extensions) or non-secure EL1. the virtualisation extensions) or non-secure EL1.
- Caches, MMUs - Caches, MMUs
The MMU must be off. The MMU must be off.
Instruction cache may be on or off. Instruction cache may be on or off.
The address range corresponding to the loaded kernel image must be The address range corresponding to the loaded kernel image must be
@ -172,18 +184,21 @@ Before jumping into the kernel, the following conditions must be met:
operations (not recommended) must be configured and disabled. operations (not recommended) must be configured and disabled.
- Architected timers - Architected timers
CNTFRQ must be programmed with the timer frequency and CNTVOFF must CNTFRQ must be programmed with the timer frequency and CNTVOFF must
be programmed with a consistent value on all CPUs. If entering the be programmed with a consistent value on all CPUs. If entering the
kernel at EL1, CNTHCTL_EL2 must have EL1PCTEN (bit 0) set where kernel at EL1, CNTHCTL_EL2 must have EL1PCTEN (bit 0) set where
available. available.
- Coherency - Coherency
All CPUs to be booted by the kernel must be part of the same coherency All CPUs to be booted by the kernel must be part of the same coherency
domain on entry to the kernel. This may require IMPLEMENTATION DEFINED domain on entry to the kernel. This may require IMPLEMENTATION DEFINED
initialisation to enable the receiving of maintenance operations on initialisation to enable the receiving of maintenance operations on
each CPU. each CPU.
- System registers - System registers
All writable architected system registers at the exception level where All writable architected system registers at the exception level where
the kernel image will be entered must be initialised by software at a the kernel image will be entered must be initialised by software at a
higher exception level to prevent execution in an UNKNOWN state. higher exception level to prevent execution in an UNKNOWN state.
@ -195,28 +210,40 @@ Before jumping into the kernel, the following conditions must be met:
For systems with a GICv3 interrupt controller to be used in v3 mode: For systems with a GICv3 interrupt controller to be used in v3 mode:
- If EL3 is present: - If EL3 is present:
ICC_SRE_EL3.Enable (bit 3) must be initialiased to 0b1.
ICC_SRE_EL3.SRE (bit 0) must be initialised to 0b1. - ICC_SRE_EL3.Enable (bit 3) must be initialiased to 0b1.
- ICC_SRE_EL3.SRE (bit 0) must be initialised to 0b1.
- If the kernel is entered at EL1: - If the kernel is entered at EL1:
ICC.SRE_EL2.Enable (bit 3) must be initialised to 0b1
ICC_SRE_EL2.SRE (bit 0) must be initialised to 0b1. - ICC.SRE_EL2.Enable (bit 3) must be initialised to 0b1
- ICC_SRE_EL2.SRE (bit 0) must be initialised to 0b1.
- The DT or ACPI tables must describe a GICv3 interrupt controller. - The DT or ACPI tables must describe a GICv3 interrupt controller.
For systems with a GICv3 interrupt controller to be used in For systems with a GICv3 interrupt controller to be used in
compatibility (v2) mode: compatibility (v2) mode:
- If EL3 is present: - If EL3 is present:
ICC_SRE_EL3.SRE (bit 0) must be initialised to 0b0.
ICC_SRE_EL3.SRE (bit 0) must be initialised to 0b0.
- If the kernel is entered at EL1: - If the kernel is entered at EL1:
ICC_SRE_EL2.SRE (bit 0) must be initialised to 0b0.
ICC_SRE_EL2.SRE (bit 0) must be initialised to 0b0.
- The DT or ACPI tables must describe a GICv2 interrupt controller. - The DT or ACPI tables must describe a GICv2 interrupt controller.
For CPUs with pointer authentication functionality: For CPUs with pointer authentication functionality:
- If EL3 is present: - If EL3 is present:
SCR_EL3.APK (bit 16) must be initialised to 0b1
SCR_EL3.API (bit 17) must be initialised to 0b1 - SCR_EL3.APK (bit 16) must be initialised to 0b1
- SCR_EL3.API (bit 17) must be initialised to 0b1
- If the kernel is entered at EL1: - If the kernel is entered at EL1:
HCR_EL2.APK (bit 40) must be initialised to 0b1
HCR_EL2.API (bit 41) must be initialised to 0b1 - HCR_EL2.APK (bit 40) must be initialised to 0b1
- HCR_EL2.API (bit 41) must be initialised to 0b1
The requirements described above for CPU mode, caches, MMUs, architected The requirements described above for CPU mode, caches, MMUs, architected
timers, coherency and system registers apply to all CPUs. All CPUs must timers, coherency and system registers apply to all CPUs. All CPUs must

204
Documentation/arm64/cpu-feature-registers.txt → Documentation/arm64/cpu-feature-registers.rst
View File

@ -1,5 +1,6 @@
ARM64 CPU Feature Registers ===========================
=========================== ARM64 CPU Feature Registers
===========================
Author: Suzuki K Poulose <suzuki.poulose@arm.com> Author: Suzuki K Poulose <suzuki.poulose@arm.com>
@ -9,7 +10,7 @@ registers to userspace. The availability of this ABI is advertised
via the HWCAP_CPUID in HWCAPs. via the HWCAP_CPUID in HWCAPs.
1. Motivation 1. Motivation
--------------- -------------
The ARM architecture defines a set of feature registers, which describe The ARM architecture defines a set of feature registers, which describe
the capabilities of the CPU/system. Access to these system registers is the capabilities of the CPU/system. Access to these system registers is
@ -33,9 +34,10 @@ there are some issues with their usage.
2. Requirements 2. Requirements
----------------- ---------------
a) Safety:
a) Safety :
Applications should be able to use the information provided by the Applications should be able to use the information provided by the
infrastructure to run safely across the system. This has greater infrastructure to run safely across the system. This has greater
implications on a system with heterogeneous CPUs. implications on a system with heterogeneous CPUs.
@ -47,7 +49,8 @@ there are some issues with their usage.
Otherwise an application could crash when scheduled on the CPU Otherwise an application could crash when scheduled on the CPU
which doesn't support CRC32. which doesn't support CRC32.
b) Security : b) Security:
Applications should only be able to receive information that is Applications should only be able to receive information that is
relevant to the normal operation in userspace. Hence, some of the relevant to the normal operation in userspace. Hence, some of the
fields are masked out(i.e, made invisible) and their values are set to fields are masked out(i.e, made invisible) and their values are set to
@ -58,10 +61,12 @@ there are some issues with their usage.
(even when the CPU provides it). (even when the CPU provides it).
c) Implementation Defined Features c) Implementation Defined Features
The infrastructure doesn't expose any register which is The infrastructure doesn't expose any register which is
IMPLEMENTATION DEFINED as per ARMv8-A Architecture. IMPLEMENTATION DEFINED as per ARMv8-A Architecture.
d) CPU Identification : d) CPU Identification:
MIDR_EL1 is exposed to help identify the processor. On a MIDR_EL1 is exposed to help identify the processor. On a
heterogeneous system, this could be racy (just like getcpu()). The heterogeneous system, this could be racy (just like getcpu()). The
process could be migrated to another CPU by the time it uses the process could be migrated to another CPU by the time it uses the
@ -70,7 +75,7 @@ there are some issues with their usage.
currently executing on. The REVIDR is not exposed due to this currently executing on. The REVIDR is not exposed due to this
constraint, as REVIDR makes sense only in conjunction with the constraint, as REVIDR makes sense only in conjunction with the
MIDR. Alternately, MIDR_EL1 and REVIDR_EL1 are exposed via sysfs MIDR. Alternately, MIDR_EL1 and REVIDR_EL1 are exposed via sysfs
at: at::
/sys/devices/system/cpu/cpu$ID/regs/identification/ /sys/devices/system/cpu/cpu$ID/regs/identification/
\- midr \- midr
@ -85,7 +90,8 @@ exception and ends up in SIGILL being delivered to the process.
The infrastructure hooks into the exception handler and emulates the The infrastructure hooks into the exception handler and emulates the
operation if the source belongs to the supported system register space. operation if the source belongs to the supported system register space.
The infrastructure emulates only the following system register space: The infrastructure emulates only the following system register space::
Op0=3, Op1=0, CRn=0, CRm=0,4,5,6,7 Op0=3, Op1=0, CRn=0, CRm=0,4,5,6,7
(See Table C5-6 'System instruction encodings for non-Debug System (See Table C5-6 'System instruction encodings for non-Debug System
@ -107,73 +113,76 @@ infrastructure:
------------------------------------------- -------------------------------------------
1) ID_AA64ISAR0_EL1 - Instruction Set Attribute Register 0 1) ID_AA64ISAR0_EL1 - Instruction Set Attribute Register 0
x--------------------------------------------------x
+------------------------------+---------+---------+
| Name | bits | visible | | Name | bits | visible |
|--------------------------------------------------| +------------------------------+---------+---------+
| TS | [55-52] | y | | TS | [55-52] | y |
|--------------------------------------------------| +------------------------------+---------+---------+
| FHM | [51-48] | y | | FHM | [51-48] | y |
|--------------------------------------------------| +------------------------------+---------+---------+
| DP | [47-44] | y | | DP | [47-44] | y |
|--------------------------------------------------| +------------------------------+---------+---------+
| SM4 | [43-40] | y | | SM4 | [43-40] | y |
|--------------------------------------------------| +------------------------------+---------+---------+
| SM3 | [39-36] | y | | SM3 | [39-36] | y |
|--------------------------------------------------| +------------------------------+---------+---------+
| SHA3 | [35-32] | y | | SHA3 | [35-32] | y |
|--------------------------------------------------| +------------------------------+---------+---------+
| RDM | [31-28] | y | | RDM | [31-28] | y |
|--------------------------------------------------| +------------------------------+---------+---------+
| ATOMICS | [23-20] | y | | ATOMICS | [23-20] | y |
|--------------------------------------------------| +------------------------------+---------+---------+
| CRC32 | [19-16] | y | | CRC32 | [19-16] | y |
|--------------------------------------------------| +------------------------------+---------+---------+
| SHA2 | [15-12] | y | | SHA2 | [15-12] | y |
|--------------------------------------------------| +------------------------------+---------+---------+
| SHA1 | [11-8] | y | | SHA1 | [11-8] | y |
|--------------------------------------------------| +------------------------------+---------+---------+
| AES | [7-4] | y | | AES | [7-4] | y |
x--------------------------------------------------x +------------------------------+---------+---------+
2) ID_AA64PFR0_EL1 - Processor Feature Register 0 2) ID_AA64PFR0_EL1 - Processor Feature Register 0
x--------------------------------------------------x
+------------------------------+---------+---------+
| Name | bits | visible | | Name | bits | visible |
|--------------------------------------------------| +------------------------------+---------+---------+
| DIT | [51-48] | y | | DIT | [51-48] | y |
|--------------------------------------------------| +------------------------------+---------+---------+
| SVE | [35-32] | y | | SVE | [35-32] | y |
|--------------------------------------------------| +------------------------------+---------+---------+
| GIC | [27-24] | n | | GIC | [27-24] | n |
|--------------------------------------------------| +------------------------------+---------+---------+
| AdvSIMD | [23-20] | y | | AdvSIMD | [23-20] | y |
|--------------------------------------------------| +------------------------------+---------+---------+
| FP | [19-16] | y | | FP | [19-16] | y |
|--------------------------------------------------| +------------------------------+---------+---------+
| EL3 | [15-12] | n | | EL3 | [15-12] | n |
|--------------------------------------------------| +------------------------------+---------+---------+
| EL2 | [11-8] | n | | EL2 | [11-8] | n |
|--------------------------------------------------| +------------------------------+---------+---------+
| EL1 | [7-4] | n | | EL1 | [7-4] | n |
|--------------------------------------------------| +------------------------------+---------+---------+
| EL0 | [3-0] | n | | EL0 | [3-0] | n |
x--------------------------------------------------x +------------------------------+---------+---------+
3) MIDR_EL1 - Main ID Register 3) MIDR_EL1 - Main ID Register
x--------------------------------------------------x
+------------------------------+---------+---------+
| Name | bits | visible | | Name | bits | visible |
|--------------------------------------------------| +------------------------------+---------+---------+
| Implementer | [31-24] | y | | Implementer | [31-24] | y |
|--------------------------------------------------| +------------------------------+---------+---------+
| Variant | [23-20] | y | | Variant | [23-20] | y |
|--------------------------------------------------| +------------------------------+---------+---------+
| Architecture | [19-16] | y | | Architecture | [19-16] | y |
|--------------------------------------------------| +------------------------------+---------+---------+
| PartNum | [15-4] | y | | PartNum | [15-4] | y |
|--------------------------------------------------| +------------------------------+---------+---------+
| Revision | [3-0] | y | | Revision | [3-0] | y |
x--------------------------------------------------x +------------------------------+---------+---------+
NOTE: The 'visible' fields of MIDR_EL1 will contain the value NOTE: The 'visible' fields of MIDR_EL1 will contain the value
as available on the CPU where it is fetched and is not a system as available on the CPU where it is fetched and is not a system
@ -181,90 +190,92 @@ infrastructure:
4) ID_AA64ISAR1_EL1 - Instruction set attribute register 1 4) ID_AA64ISAR1_EL1 - Instruction set attribute register 1
x--------------------------------------------------x +------------------------------+---------+---------+
| Name | bits | visible | | Name | bits | visible |
|--------------------------------------------------| +------------------------------+---------+---------+
| GPI | [31-28] | y | | GPI | [31-28] | y |
|--------------------------------------------------| +------------------------------+---------+---------+
| GPA | [27-24] | y | | GPA | [27-24] | y |
|--------------------------------------------------| +------------------------------+---------+---------+
| LRCPC | [23-20] | y | | LRCPC | [23-20] | y |
|--------------------------------------------------| +------------------------------+---------+---------+
| FCMA | [19-16] | y | | FCMA | [19-16] | y |
|--------------------------------------------------| +------------------------------+---------+---------+
| JSCVT | [15-12] | y | | JSCVT | [15-12] | y |
|--------------------------------------------------| +------------------------------+---------+---------+
| API | [11-8] | y | | API | [11-8] | y |
|--------------------------------------------------| +------------------------------+---------+---------+
| APA | [7-4] | y | | APA | [7-4] | y |
|--------------------------------------------------| +------------------------------+---------+---------+
| DPB | [3-0] | y | | DPB | [3-0] | y |
x--------------------------------------------------x +------------------------------+---------+---------+
5) ID_AA64MMFR2_EL1 - Memory model feature register 2 5) ID_AA64MMFR2_EL1 - Memory model feature register 2
x--------------------------------------------------x +------------------------------+---------+---------+
| Name | bits | visible | | Name | bits | visible |
|--------------------------------------------------| +------------------------------+---------+---------+
| AT | [35-32] | y | | AT | [35-32] | y |
x--------------------------------------------------x +------------------------------+---------+---------+
6) ID_AA64ZFR0_EL1 - SVE feature ID register 0 6) ID_AA64ZFR0_EL1 - SVE feature ID register 0
x--------------------------------------------------x +------------------------------+---------+---------+
| Name | bits | visible | | Name | bits | visible |
|--------------------------------------------------| +------------------------------+---------+---------+
| SM4 | [43-40] | y | | SM4 | [43-40] | y |
|--------------------------------------------------| +------------------------------+---------+---------+
| SHA3 | [35-32] | y | | SHA3 | [35-32] | y |
|--------------------------------------------------| +------------------------------+---------+---------+
| BitPerm | [19-16] | y | | BitPerm | [19-16] | y |
|--------------------------------------------------| +------------------------------+---------+---------+
| AES | [7-4] | y | | AES | [7-4] | y |
|--------------------------------------------------| +------------------------------+---------+---------+
| SVEVer | [3-0] | y | | SVEVer | [3-0] | y |
x--------------------------------------------------x +------------------------------+---------+---------+
Appendix I: Example Appendix I: Example
--------------------------- -------------------
/* ::
* Sample program to demonstrate the MRS emulation ABI.
*
* Copyright (C) 2015-2016, ARM Ltd
*
* Author: Suzuki K Poulose <suzuki.poulose@arm.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <asm/hwcap.h> /*
#include <stdio.h> * Sample program to demonstrate the MRS emulation ABI.
#include <sys/auxv.h> *
* Copyright (C) 2015-2016, ARM Ltd
*
* Author: Suzuki K Poulose <suzuki.poulose@arm.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#define get_cpu_ftr(id) ({ \ #include <asm/hwcap.h>
#include <stdio.h>
#include <sys/auxv.h>
#define get_cpu_ftr(id) ({ \
unsigned long __val; \ unsigned long __val; \
asm("mrs %0, "#id : "=r" (__val)); \ asm("mrs %0, "#id : "=r" (__val)); \
printf("%-20s: 0x%016lx\n", #id, __val); \ printf("%-20s: 0x%016lx\n", #id, __val); \
}) })
int main(void) int main(void)
{ {
if (!(getauxval(AT_HWCAP) & HWCAP_CPUID)) { if (!(getauxval(AT_HWCAP) & HWCAP_CPUID)) {
fputs("CPUID registers unavailable\n", stderr); fputs("CPUID registers unavailable\n", stderr);
@ -284,13 +295,10 @@ int main(void)
get_cpu_ftr(MPIDR_EL1); get_cpu_ftr(MPIDR_EL1);
get_cpu_ftr(REVIDR_EL1); get_cpu_ftr(REVIDR_EL1);
#if 0 #if 0
/* Unexposed register access causes SIGILL */ /* Unexposed register access causes SIGILL */
get_cpu_ftr(ID_MMFR0_EL1); get_cpu_ftr(ID_MMFR0_EL1);
#endif #endif
return 0; return 0;
} }

56
Documentation/arm64/elf_hwcaps.txt → Documentation/arm64/elf_hwcaps.rst
View File

@ -1,3 +1,4 @@
================
ARM64 ELF hwcaps ARM64 ELF hwcaps
================ ================
@ -15,16 +16,16 @@ of flags called hwcaps, exposed in the auxilliary vector.
Userspace software can test for features by acquiring the AT_HWCAP or Userspace software can test for features by acquiring the AT_HWCAP or
AT_HWCAP2 entry of the auxiliary vector, and testing whether the relevant AT_HWCAP2 entry of the auxiliary vector, and testing whether the relevant
flags are set, e.g. flags are set, e.g.::
bool floating_point_is_present(void) bool floating_point_is_present(void)
{ {
unsigned long hwcaps = getauxval(AT_HWCAP); unsigned long hwcaps = getauxval(AT_HWCAP);
if (hwcaps & HWCAP_FP) if (hwcaps & HWCAP_FP)
return true; return true;
return false; return false;
} }
Where software relies on a feature described by a hwcap, it should check Where software relies on a feature described by a hwcap, it should check
the relevant hwcap flag to verify that the feature is present before the relevant hwcap flag to verify that the feature is present before
@ -45,7 +46,7 @@ userspace code at EL0. These hwcaps are defined in terms of ID register
fields, and should be interpreted with reference to the definition of fields, and should be interpreted with reference to the definition of
these fields in the ARM Architecture Reference Manual (ARM ARM). these fields in the ARM Architecture Reference Manual (ARM ARM).
Such hwcaps are described below in the form: Such hwcaps are described below in the form::
Functionality implied by idreg.field == val. Functionality implied by idreg.field == val.
@ -64,75 +65,58 @@ reference to ID registers, and may refer to other documentation.
--------------------------------- ---------------------------------
HWCAP_FP HWCAP_FP
Functionality implied by ID_AA64PFR0_EL1.FP == 0b0000. Functionality implied by ID_AA64PFR0_EL1.FP == 0b0000.
HWCAP_ASIMD HWCAP_ASIMD
Functionality implied by ID_AA64PFR0_EL1.AdvSIMD == 0b0000. Functionality implied by ID_AA64PFR0_EL1.AdvSIMD == 0b0000.
HWCAP_EVTSTRM HWCAP_EVTSTRM
The generic timer is configured to generate events at a frequency of The generic timer is configured to generate events at a frequency of
approximately 100KHz. approximately 100KHz.
HWCAP_AES HWCAP_AES
Functionality implied by ID_AA64ISAR0_EL1.AES == 0b0001. Functionality implied by ID_AA64ISAR0_EL1.AES == 0b0001.
HWCAP_PMULL HWCAP_PMULL
Functionality implied by ID_AA64ISAR0_EL1.AES == 0b0010. Functionality implied by ID_AA64ISAR0_EL1.AES == 0b0010.
HWCAP_SHA1 HWCAP_SHA1
Functionality implied by ID_AA64ISAR0_EL1.SHA1 == 0b0001. Functionality implied by ID_AA64ISAR0_EL1.SHA1 == 0b0001.
HWCAP_SHA2 HWCAP_SHA2
Functionality implied by ID_AA64ISAR0_EL1.SHA2 == 0b0001. Functionality implied by ID_AA64ISAR0_EL1.SHA2 == 0b0001.
HWCAP_CRC32 HWCAP_CRC32
Functionality implied by ID_AA64ISAR0_EL1.CRC32 == 0b0001. Functionality implied by ID_AA64ISAR0_EL1.CRC32 == 0b0001.
HWCAP_ATOMICS HWCAP_ATOMICS
Functionality implied by ID_AA64ISAR0_EL1.Atomic == 0b0010. Functionality implied by ID_AA64ISAR0_EL1.Atomic == 0b0010.
HWCAP_FPHP HWCAP_FPHP
Functionality implied by ID_AA64PFR0_EL1.FP == 0b0001. Functionality implied by ID_AA64PFR0_EL1.FP == 0b0001.
HWCAP_ASIMDHP HWCAP_ASIMDHP
Functionality implied by ID_AA64PFR0_EL1.AdvSIMD == 0b0001. Functionality implied by ID_AA64PFR0_EL1.AdvSIMD == 0b0001.
HWCAP_CPUID HWCAP_CPUID
EL0 access to certain ID registers is available, to the extent EL0 access to certain ID registers is available, to the extent
described by Documentation/arm64/cpu-feature-registers.txt. described by Documentation/arm64/cpu-feature-registers.rst.
These ID registers may imply the availability of features. These ID registers may imply the availability of features.
HWCAP_ASIMDRDM HWCAP_ASIMDRDM
Functionality implied by ID_AA64ISAR0_EL1.RDM == 0b0001. Functionality implied by ID_AA64ISAR0_EL1.RDM == 0b0001.
HWCAP_JSCVT HWCAP_JSCVT
Functionality implied by ID_AA64ISAR1_EL1.JSCVT == 0b0001. Functionality implied by ID_AA64ISAR1_EL1.JSCVT == 0b0001.
HWCAP_FCMA HWCAP_FCMA
Functionality implied by ID_AA64ISAR1_EL1.FCMA == 0b0001. Functionality implied by ID_AA64ISAR1_EL1.FCMA == 0b0001.
HWCAP_LRCPC HWCAP_LRCPC
Functionality implied by ID_AA64ISAR1_EL1.LRCPC == 0b0001. Functionality implied by ID_AA64ISAR1_EL1.LRCPC == 0b0001.
HWCAP_DCPOP HWCAP_DCPOP
Functionality implied by ID_AA64ISAR1_EL1.DPB == 0b0001. Functionality implied by ID_AA64ISAR1_EL1.DPB == 0b0001.
HWCAP2_DCPODP HWCAP2_DCPODP
@ -140,27 +124,21 @@ HWCAP2_DCPODP
Functionality implied by ID_AA64ISAR1_EL1.DPB == 0b0010. Functionality implied by ID_AA64ISAR1_EL1.DPB == 0b0010.
HWCAP_SHA3 HWCAP_SHA3
Functionality implied by ID_AA64ISAR0_EL1.SHA3 == 0b0001. Functionality implied by ID_AA64ISAR0_EL1.SHA3 == 0b0001.
HWCAP_SM3 HWCAP_SM3
Functionality implied by ID_AA64ISAR0_EL1.SM3 == 0b0001. Functionality implied by ID_AA64ISAR0_EL1.SM3 == 0b0001.
HWCAP_SM4 HWCAP_SM4
Functionality implied by ID_AA64ISAR0_EL1.SM4 == 0b0001. Functionality implied by ID_AA64ISAR0_EL1.SM4 == 0b0001.
HWCAP_ASIMDDP HWCAP_ASIMDDP
Functionality implied by ID_AA64ISAR0_EL1.DP == 0b0001. Functionality implied by ID_AA64ISAR0_EL1.DP == 0b0001.
HWCAP_SHA512 HWCAP_SHA512
Functionality implied by ID_AA64ISAR0_EL1.SHA2 == 0b0010. Functionality implied by ID_AA64ISAR0_EL1.SHA2 == 0b0010.
HWCAP_SVE HWCAP_SVE
Functionality implied by ID_AA64PFR0_EL1.SVE == 0b0001. Functionality implied by ID_AA64PFR0_EL1.SVE == 0b0001.
HWCAP2_SVE2 HWCAP2_SVE2
@ -188,23 +166,18 @@ HWCAP2_SVESM4
Functionality implied by ID_AA64ZFR0_EL1.SM4 == 0b0001. Functionality implied by ID_AA64ZFR0_EL1.SM4 == 0b0001.
HWCAP_ASIMDFHM HWCAP_ASIMDFHM
Functionality implied by ID_AA64ISAR0_EL1.FHM == 0b0001. Functionality implied by ID_AA64ISAR0_EL1.FHM == 0b0001.
HWCAP_DIT HWCAP_DIT
Functionality implied by ID_AA64PFR0_EL1.DIT == 0b0001. Functionality implied by ID_AA64PFR0_EL1.DIT == 0b0001.
HWCAP_USCAT HWCAP_USCAT
Functionality implied by ID_AA64MMFR2_EL1.AT == 0b0001. Functionality implied by ID_AA64MMFR2_EL1.AT == 0b0001.
HWCAP_ILRCPC HWCAP_ILRCPC
Functionality implied by ID_AA64ISAR1_EL1.LRCPC == 0b0010. Functionality implied by ID_AA64ISAR1_EL1.LRCPC == 0b0010.
HWCAP_FLAGM HWCAP_FLAGM
Functionality implied by ID_AA64ISAR0_EL1.TS == 0b0001. Functionality implied by ID_AA64ISAR0_EL1.TS == 0b0001.
HWCAP2_FLAGM2 HWCAP2_FLAGM2
@ -212,20 +185,17 @@ HWCAP2_FLAGM2
Functionality implied by ID_AA64ISAR0_EL1.TS == 0b0010. Functionality implied by ID_AA64ISAR0_EL1.TS == 0b0010.
HWCAP_SSBS HWCAP_SSBS
Functionality implied by ID_AA64PFR1_EL1.SSBS == 0b0010. Functionality implied by ID_AA64PFR1_EL1.SSBS == 0b0010.
HWCAP_PACA HWCAP_PACA
Functionality implied by ID_AA64ISAR1_EL1.APA == 0b0001 or Functionality implied by ID_AA64ISAR1_EL1.APA == 0b0001 or
ID_AA64ISAR1_EL1.API == 0b0001, as described by ID_AA64ISAR1_EL1.API == 0b0001, as described by
Documentation/arm64/pointer-authentication.txt. Documentation/arm64/pointer-authentication.rst.
HWCAP_PACG HWCAP_PACG
Functionality implied by ID_AA64ISAR1_EL1.GPA == 0b0001 or Functionality implied by ID_AA64ISAR1_EL1.GPA == 0b0001 or
ID_AA64ISAR1_EL1.GPI == 0b0001, as described by ID_AA64ISAR1_EL1.GPI == 0b0001, as described by
Documentation/arm64/pointer-authentication.txt. Documentation/arm64/pointer-authentication.rst.
HWCAP2_FRINT HWCAP2_FRINT

7
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View File

@ -1,3 +1,4 @@
====================
HugeTLBpage on ARM64 HugeTLBpage on ARM64
==================== ====================
@ -31,8 +32,10 @@ and level of the page table.
The following hugepage sizes are supported - The following hugepage sizes are supported -
CONT PTE PMD CONT PMD PUD ====== ======== ==== ======== ===
-------- --- -------- --- - CONT PTE PMD CONT PMD PUD
====== ======== ==== ======== ===
4K: 64K 2M 32M 1G 4K: 64K 2M 32M 1G
16K: 2M 32M 1G 16K: 2M 32M 1G
64K: 2M 512M 16G 64K: 2M 512M 16G
====== ======== ==== ======== ===

28
Documentation/arm64/index.rst Normal file
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@ -0,0 +1,28 @@
:orphan:
==================
ARM64 Architecture
==================
.. toctree::
:maxdepth: 1
acpi_object_usage
arm-acpi
booting
cpu-feature-registers
elf_hwcaps
hugetlbpage
legacy_instructions
memory
pointer-authentication
silicon-errata
sve
tagged-pointers
.. only:: subproject and html
Indices
=======
* :ref:`genindex`

43
Documentation/arm64/legacy_instructions.txt → Documentation/arm64/legacy_instructions.rst
View File

@ -1,3 +1,7 @@
===================
Legacy instructions
===================
The arm64 port of the Linux kernel provides infrastructure to support The arm64 port of the Linux kernel provides infrastructure to support
emulation of instructions which have been deprecated, or obsoleted in emulation of instructions which have been deprecated, or obsoleted in
the architecture. The infrastructure code uses undefined instruction the architecture. The infrastructure code uses undefined instruction
@ -9,19 +13,22 @@ The emulation mode can be controlled by writing to sysctl nodes
behaviours and the corresponding values of the sysctl nodes - behaviours and the corresponding values of the sysctl nodes -
* Undef * Undef
Value: 0 Value: 0
Generates undefined instruction abort. Default for instructions that Generates undefined instruction abort. Default for instructions that
have been obsoleted in the architecture, e.g., SWP have been obsoleted in the architecture, e.g., SWP
* Emulate * Emulate
Value: 1 Value: 1
Uses software emulation. To aid migration of software, in this mode Uses software emulation. To aid migration of software, in this mode
usage of emulated instruction is traced as well as rate limited usage of emulated instruction is traced as well as rate limited
warnings are issued. This is the default for deprecated warnings are issued. This is the default for deprecated
instructions, .e.g., CP15 barriers instructions, .e.g., CP15 barriers
* Hardware Execution * Hardware Execution
Value: 2 Value: 2
Although marked as deprecated, some implementations may support the Although marked as deprecated, some implementations may support the
enabling/disabling of hardware support for the execution of these enabling/disabling of hardware support for the execution of these
instructions. Using hardware execution generally provides better instructions. Using hardware execution generally provides better
@ -38,20 +45,24 @@ individual instruction notes for further information.
Supported legacy instructions Supported legacy instructions
----------------------------- -----------------------------
* SWP{B} * SWP{B}
Node: /proc/sys/abi/swp
Status: Obsolete :Node: /proc/sys/abi/swp
Default: Undef (0) :Status: Obsolete
:Default: Undef (0)
* CP15 Barriers * CP15 Barriers
Node: /proc/sys/abi/cp15_barrier
Status: Deprecated :Node: /proc/sys/abi/cp15_barrier
Default: Emulate (1) :Status: Deprecated
:Default: Emulate (1)
* SETEND * SETEND
Node: /proc/sys/abi/setend
Status: Deprecated :Node: /proc/sys/abi/setend
Default: Emulate (1)* :Status: Deprecated
Note: All the cpus on the system must have mixed endian support at EL0 :Default: Emulate (1)*
for this feature to be enabled. If a new CPU - which doesn't support mixed
endian - is hotplugged in after this feature has been enabled, there could Note: All the cpus on the system must have mixed endian support at EL0
be unexpected results in the application. for this feature to be enabled. If a new CPU - which doesn't support mixed
endian - is hotplugged in after this feature has been enabled, there could
be unexpected results in the application.

98
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@ -0,0 +1,98 @@
==============================
Memory Layout on AArch64 Linux
==============================
Author: Catalin Marinas <catalin.marinas@arm.com>
This document describes the virtual memory layout used by the AArch64
Linux kernel. The architecture allows up to 4 levels of translation
tables with a 4KB page size and up to 3 levels with a 64KB page size.
AArch64 Linux uses either 3 levels or 4 levels of translation tables
with the 4KB page configuration, allowing 39-bit (512GB) or 48-bit
(256TB) virtual addresses, respectively, for both user and kernel. With
64KB pages, only 2 levels of translation tables, allowing 42-bit (4TB)
virtual address, are used but the memory layout is the same.
User addresses have bits 63:48 set to 0 while the kernel addresses have
the same bits set to 1. TTBRx selection is given by bit 63 of the
virtual address. The swapper_pg_dir contains only kernel (global)
mappings while the user pgd contains only user (non-global) mappings.
The swapper_pg_dir address is written to TTBR1 and never written to
TTBR0.
AArch64 Linux memory layout with 4KB pages + 3 levels::
Start End Size Use
-----------------------------------------------------------------------
0000000000000000 0000007fffffffff 512GB user
ffffff8000000000 ffffffffffffffff 512GB kernel
AArch64 Linux memory layout with 4KB pages + 4 levels::
Start End Size Use
-----------------------------------------------------------------------
0000000000000000 0000ffffffffffff 256TB user
ffff000000000000 ffffffffffffffff 256TB kernel
AArch64 Linux memory layout with 64KB pages + 2 levels::
Start End Size Use
-----------------------------------------------------------------------
0000000000000000 000003ffffffffff 4TB user
fffffc0000000000 ffffffffffffffff 4TB kernel
AArch64 Linux memory layout with 64KB pages + 3 levels::
Start End Size Use
-----------------------------------------------------------------------
0000000000000000 0000ffffffffffff 256TB user
ffff000000000000 ffffffffffffffff 256TB kernel
For details of the virtual kernel memory layout please see the kernel
booting log.
Translation table lookup with 4KB pages::
+--------+--------+--------+--------+--------+--------+--------+--------+
|63 56|55 48|47 40|39 32|31 24|23 16|15 8|7 0|
+--------+--------+--------+--------+--------+--------+--------+--------+
| | | | | |
| | | | | v
| | | | | [11:0] in-page offset
| | | | +-> [20:12] L3 index
| | | +-----------> [29:21] L2 index
| | +---------------------> [38:30] L1 index
| +-------------------------------> [47:39] L0 index
+-------------------------------------------------> [63] TTBR0/1
Translation table lookup with 64KB pages::
+--------+--------+--------+--------+--------+--------+--------+--------+
|63 56|55 48|47 40|39 32|31 24|23 16|15 8|7 0|
+--------+--------+--------+--------+--------+--------+--------+--------+
| | | | |
| | | | v
| | | | [15:0] in-page offset
| | | +----------> [28:16] L3 index
| | +--------------------------> [41:29] L2 index
| +-------------------------------> [47:42] L1 index
+-------------------------------------------------> [63] TTBR0/1
When using KVM without the Virtualization Host Extensions, the
hypervisor maps kernel pages in EL2 at a fixed (and potentially
random) offset from the linear mapping. See the kern_hyp_va macro and
kvm_update_va_mask function for more details. MMIO devices such as
GICv2 gets mapped next to the HYP idmap page, as do vectors when
ARM64_HARDEN_EL2_VECTORS is selected for particular CPUs.
When using KVM with the Virtualization Host Extensions, no additional
mappings are created, since the host kernel runs directly in EL2.

97
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View File

@ -1,97 +0,0 @@
Memory Layout on AArch64 Linux
==============================
Author: Catalin Marinas <catalin.marinas@arm.com>
This document describes the virtual memory layout used by the AArch64
Linux kernel. The architecture allows up to 4 levels of translation
tables with a 4KB page size and up to 3 levels with a 64KB page size.
AArch64 Linux uses either 3 levels or 4 levels of translation tables
with the 4KB page configuration, allowing 39-bit (512GB) or 48-bit
(256TB) virtual addresses, respectively, for both user and kernel. With
64KB pages, only 2 levels of translation tables, allowing 42-bit (4TB)
virtual address, are used but the memory layout is the same.
User addresses have bits 63:48 set to 0 while the kernel addresses have
the same bits set to 1. TTBRx selection is given by bit 63 of the
virtual address. The swapper_pg_dir contains only kernel (global)
mappings while the user pgd contains only user (non-global) mappings.
The swapper_pg_dir address is written to TTBR1 and never written to
TTBR0.
AArch64 Linux memory layout with 4KB pages + 3 levels:
Start End Size Use
-----------------------------------------------------------------------
0000000000000000 0000007fffffffff 512GB user
ffffff8000000000 ffffffffffffffff 512GB kernel
AArch64 Linux memory layout with 4KB pages + 4 levels:
Start End Size Use
-----------------------------------------------------------------------
0000000000000000 0000ffffffffffff 256TB user
ffff000000000000 ffffffffffffffff 256TB kernel
AArch64 Linux memory layout with 64KB pages + 2 levels:
Start End Size Use
-----------------------------------------------------------------------
0000000000000000 000003ffffffffff 4TB user
fffffc0000000000 ffffffffffffffff 4TB kernel
AArch64 Linux memory layout with 64KB pages + 3 levels:
Start End Size Use
-----------------------------------------------------------------------
0000000000000000 0000ffffffffffff 256TB user
ffff000000000000 ffffffffffffffff 256TB kernel
For details of the virtual kernel memory layout please see the kernel
booting log.
Translation table lookup with 4KB pages:
+--------+--------+--------+--------+--------+--------+--------+--------+
|63 56|55 48|47 40|39 32|31 24|23 16|15 8|7 0|
+--------+--------+--------+--------+--------+--------+--------+--------+
| | | | | |
| | | | | v
| | | | | [11:0] in-page offset
| | | | +-> [20:12] L3 index
| | | +-----------> [29:21] L2 index
| | +---------------------> [38:30] L1 index
| +-------------------------------> [47:39] L0 index
+-------------------------------------------------> [63] TTBR0/1
Translation table lookup with 64KB pages:
+--------+--------+--------+--------+--------+--------+--------+--------+
|63 56|55 48|47 40|39 32|31 24|23 16|15 8|7 0|
+--------+--------+--------+--------+--------+--------+--------+--------+
| | | | |
| | | | v
| | | | [15:0] in-page offset
| | | +----------> [28:16] L3 index
| | +--------------------------> [41:29] L2 index
| +-------------------------------> [47:42] L1 index
+-------------------------------------------------> [63] TTBR0/1
When using KVM without the Virtualization Host Extensions, the
hypervisor maps kernel pages in EL2 at a fixed (and potentially
random) offset from the linear mapping. See the kern_hyp_va macro and
kvm_update_va_mask function for more details. MMIO devices such as
GICv2 gets mapped next to the HYP idmap page, as do vectors when
ARM64_HARDEN_EL2_VECTORS is selected for particular CPUs.
When using KVM with the Virtualization Host Extensions, no additional
mappings are created, since the host kernel runs directly in EL2.

2
Documentation/arm64/pointer-authentication.txt → Documentation/arm64/pointer-authentication.rst
View File

@ -1,7 +1,9 @@
=======================================
Pointer authentication in AArch64 Linux Pointer authentication in AArch64 Linux
======================================= =======================================
Author: Mark Rutland <mark.rutland@arm.com> Author: Mark Rutland <mark.rutland@arm.com>
Date: 2017-07-19 Date: 2017-07-19
This document briefly describes the provision of pointer authentication This document briefly describes the provision of pointer authentication

65
Documentation/arm64/silicon-errata.txt → Documentation/arm64/silicon-errata.rst
View File

@ -1,7 +1,9 @@
Silicon Errata and Software Workarounds =======================================
======================================= Silicon Errata and Software Workarounds
=======================================
Author: Will Deacon <will.deacon@arm.com> Author: Will Deacon <will.deacon@arm.com>
Date : 27 November 2015 Date : 27 November 2015
It is an unfortunate fact of life that hardware is often produced with It is an unfortunate fact of life that hardware is often produced with
@ -9,11 +11,13 @@ so-called "errata", which can cause it to deviate from the architecture
under specific circumstances. For hardware produced by ARM, these under specific circumstances. For hardware produced by ARM, these
errata are broadly classified into the following categories: errata are broadly classified into the following categories:
Category A: A critical error without a viable workaround. ========== ========================================================
Category B: A significant or critical error with an acceptable Category A A critical error without a viable workaround.
Category B A significant or critical error with an acceptable
workaround. workaround.
Category C: A minor error that is not expected to occur under normal Category C A minor error that is not expected to occur under normal
operation. operation.
========== ========================================================
For more information, consult one of the "Software Developers Errata For more information, consult one of the "Software Developers Errata
Notice" documents available on infocenter.arm.com (registration Notice" documents available on infocenter.arm.com (registration
@ -42,47 +46,86 @@ file acts as a registry of software workarounds in the Linux Kernel and
will be updated when new workarounds are committed and backported to will be updated when new workarounds are committed and backported to
stable kernels. stable kernels.
| Implementor | Component | Erratum ID | Kconfig |
+----------------+-----------------+-----------------+-----------------------------+ +----------------+-----------------+-----------------+-----------------------------+
| Implementor | Component | Erratum ID | Kconfig |
+================+=================+=================+=============================+
| Allwinner | A64/R18 | UNKNOWN1 | SUN50I_ERRATUM_UNKNOWN1 | | Allwinner | A64/R18 | UNKNOWN1 | SUN50I_ERRATUM_UNKNOWN1 |
| | | | | +----------------+-----------------+-----------------+-----------------------------+
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A53 | #826319 | ARM64_ERRATUM_826319 | | ARM | Cortex-A53 | #826319 | ARM64_ERRATUM_826319 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A53 | #827319 | ARM64_ERRATUM_827319 | | ARM | Cortex-A53 | #827319 | ARM64_ERRATUM_827319 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A53 | #824069 | ARM64_ERRATUM_824069 | | ARM | Cortex-A53 | #824069 | ARM64_ERRATUM_824069 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A53 | #819472 | ARM64_ERRATUM_819472 | | ARM | Cortex-A53 | #819472 | ARM64_ERRATUM_819472 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A53 | #845719 | ARM64_ERRATUM_845719 | | ARM | Cortex-A53 | #845719 | ARM64_ERRATUM_845719 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A53 | #843419 | ARM64_ERRATUM_843419 | | ARM | Cortex-A53 | #843419 | ARM64_ERRATUM_843419 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A57 | #832075 | ARM64_ERRATUM_832075 | | ARM | Cortex-A57 | #832075 | ARM64_ERRATUM_832075 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A57 | #852523 | N/A | | ARM | Cortex-A57 | #852523 | N/A |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A57 | #834220 | ARM64_ERRATUM_834220 | | ARM | Cortex-A57 | #834220 | ARM64_ERRATUM_834220 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A72 | #853709 | N/A | | ARM | Cortex-A72 | #853709 | N/A |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A73 | #858921 | ARM64_ERRATUM_858921 | | ARM | Cortex-A73 | #858921 | ARM64_ERRATUM_858921 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A55 | #1024718 | ARM64_ERRATUM_1024718 | | ARM | Cortex-A55 | #1024718 | ARM64_ERRATUM_1024718 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A76 | #1188873,1418040| ARM64_ERRATUM_1418040 | | ARM | Cortex-A76 | #1188873,1418040| ARM64_ERRATUM_1418040 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A76 | #1165522 | ARM64_ERRATUM_1165522 | | ARM | Cortex-A76 | #1165522 | ARM64_ERRATUM_1165522 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A76 | #1286807 | ARM64_ERRATUM_1286807 | | ARM | Cortex-A76 | #1286807 | ARM64_ERRATUM_1286807 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A76 | #1463225 | ARM64_ERRATUM_1463225 | | ARM | Cortex-A76 | #1463225 | ARM64_ERRATUM_1463225 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Neoverse-N1 | #1188873,1418040| ARM64_ERRATUM_1418040 | | ARM | Neoverse-N1 | #1188873,1418040| ARM64_ERRATUM_1418040 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | MMU-500 | #841119,826419 | N/A | | ARM | MMU-500 | #841119,826419 | N/A |
| | | | | +----------------+-----------------+-----------------+-----------------------------+
+----------------+-----------------+-----------------+-----------------------------+
| Cavium | ThunderX ITS | #22375,24313 | CAVIUM_ERRATUM_22375 | | Cavium | ThunderX ITS | #22375,24313 | CAVIUM_ERRATUM_22375 |
+----------------+-----------------+-----------------+-----------------------------+
| Cavium | ThunderX ITS | #23144 | CAVIUM_ERRATUM_23144 | | Cavium | ThunderX ITS | #23144 | CAVIUM_ERRATUM_23144 |
+----------------+-----------------+-----------------+-----------------------------+
| Cavium | ThunderX GICv3 | #23154 | CAVIUM_ERRATUM_23154 | | Cavium | ThunderX GICv3 | #23154 | CAVIUM_ERRATUM_23154 |
+----------------+-----------------+-----------------+-----------------------------+
| Cavium | ThunderX Core | #27456 | CAVIUM_ERRATUM_27456 | | Cavium | ThunderX Core | #27456 | CAVIUM_ERRATUM_27456 |
+----------------+-----------------+-----------------+-----------------------------+
| Cavium | ThunderX Core | #30115 | CAVIUM_ERRATUM_30115 | | Cavium | ThunderX Core | #30115 | CAVIUM_ERRATUM_30115 |
+----------------+-----------------+-----------------+-----------------------------+
| Cavium | ThunderX SMMUv2 | #27704 | N/A | | Cavium | ThunderX SMMUv2 | #27704 | N/A |
+----------------+-----------------+-----------------+-----------------------------+
| Cavium | ThunderX2 SMMUv3| #74 | N/A | | Cavium | ThunderX2 SMMUv3| #74 | N/A |
+----------------+-----------------+-----------------+-----------------------------+
| Cavium | ThunderX2 SMMUv3| #126 | N/A | | Cavium | ThunderX2 SMMUv3| #126 | N/A |
| | | | | +----------------+-----------------+-----------------+-----------------------------+
+----------------+-----------------+-----------------+-----------------------------+
| Freescale/NXP | LS2080A/LS1043A | A-008585 | FSL_ERRATUM_A008585 | | Freescale/NXP | LS2080A/LS1043A | A-008585 | FSL_ERRATUM_A008585 |
| | | | | +----------------+-----------------+-----------------+-----------------------------+
+----------------+-----------------+-----------------+-----------------------------+
| Hisilicon | Hip0{5,6,7} | #161010101 | HISILICON_ERRATUM_161010101 | | Hisilicon | Hip0{5,6,7} | #161010101 | HISILICON_ERRATUM_161010101 |
+----------------+-----------------+-----------------+-----------------------------+
| Hisilicon | Hip0{6,7} | #161010701 | N/A | | Hisilicon | Hip0{6,7} | #161010701 | N/A |
+----------------+-----------------+-----------------+-----------------------------+
| Hisilicon | Hip07 | #161600802 | HISILICON_ERRATUM_161600802 | | Hisilicon | Hip07 | #161600802 | HISILICON_ERRATUM_161600802 |
+----------------+-----------------+-----------------+-----------------------------+
| Hisilicon | Hip08 SMMU PMCG | #162001800 | N/A | | Hisilicon | Hip08 SMMU PMCG | #162001800 | N/A |
| | | | | +----------------+-----------------+-----------------+-----------------------------+
+----------------+-----------------+-----------------+-----------------------------+
| Qualcomm Tech. | Kryo/Falkor v1 | E1003 | QCOM_FALKOR_ERRATUM_1003 | | Qualcomm Tech. | Kryo/Falkor v1 | E1003 | QCOM_FALKOR_ERRATUM_1003 |
+----------------+-----------------+-----------------+-----------------------------+
| Qualcomm Tech. | Falkor v1 | E1009 | QCOM_FALKOR_ERRATUM_1009 | | Qualcomm Tech. | Falkor v1 | E1009 | QCOM_FALKOR_ERRATUM_1009 |
+----------------+-----------------+-----------------+-----------------------------+
| Qualcomm Tech. | QDF2400 ITS | E0065 | QCOM_QDF2400_ERRATUM_0065 | | Qualcomm Tech. | QDF2400 ITS | E0065 | QCOM_QDF2400_ERRATUM_0065 |
+----------------+-----------------+-----------------+-----------------------------+
| Qualcomm Tech. | Falkor v{1,2} | E1041 | QCOM_FALKOR_ERRATUM_1041 | | Qualcomm Tech. | Falkor v{1,2} | E1041 | QCOM_FALKOR_ERRATUM_1041 |
+----------------+-----------------+-----------------+-----------------------------+
+----------------+-----------------+-----------------+-----------------------------+
| Fujitsu | A64FX | E#010001 | FUJITSU_ERRATUM_010001 | | Fujitsu | A64FX | E#010001 | FUJITSU_ERRATUM_010001 |
+----------------+-----------------+-----------------+-----------------------------+

12
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@ -1,7 +1,9 @@
Scalable Vector Extension support for AArch64 Linux ===================================================
=================================================== Scalable Vector Extension support for AArch64 Linux
===================================================
Author: Dave Martin <Dave.Martin@arm.com> Author: Dave Martin <Dave.Martin@arm.com>
Date: 4 August 2017 Date: 4 August 2017
This document outlines briefly the interface provided to userspace by Linux in This document outlines briefly the interface provided to userspace by Linux in
@ -442,7 +444,7 @@ In A64 state, SVE adds the following:
* FPSR and FPCR are retained from ARMv8-A, and interact with SVE floating-point * FPSR and FPCR are retained from ARMv8-A, and interact with SVE floating-point
operations in a similar way to the way in which they interact with ARMv8 operations in a similar way to the way in which they interact with ARMv8
floating-point operations. floating-point operations::
8VL-1 128 0 bit index 8VL-1 128 0 bit index
+---- //// -----------------+ +---- //// -----------------+
@ -499,6 +501,8 @@ ARMv8-A defines the following floating-point / SIMD register state:
* 32 128-bit vector registers V0..V31 * 32 128-bit vector registers V0..V31
* 2 32-bit status/control registers FPSR, FPCR * 2 32-bit status/control registers FPSR, FPCR
::
127 0 bit index 127 0 bit index
+---------------+ +---------------+
V0 | | V0 | |
@ -533,7 +537,7 @@ References
[2] arch/arm64/include/uapi/asm/ptrace.h [2] arch/arm64/include/uapi/asm/ptrace.h
AArch64 Linux ptrace ABI definitions AArch64 Linux ptrace ABI definitions
[3] Documentation/arm64/cpu-feature-registers.txt [3] Documentation/arm64/cpu-feature-registers.rst
[4] ARM IHI0055C [4] ARM IHI0055C
http://infocenter.arm.com/help/topic/com.arm.doc.ihi0055c/IHI0055C_beta_aapcs64.pdf http://infocenter.arm.com/help/topic/com.arm.doc.ihi0055c/IHI0055C_beta_aapcs64.pdf

6
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@ -1,7 +1,9 @@
Tagged virtual addresses in AArch64 Linux =========================================
========================================= Tagged virtual addresses in AArch64 Linux
=========================================
Author: Will Deacon <will.deacon@arm.com> Author: Will Deacon <will.deacon@arm.com>
Date : 12 June 2013 Date : 12 June 2013
This document briefly describes the provision of tagged virtual This document briefly describes the provision of tagged virtual

2
Documentation/bpf/btf.rst
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@ -151,6 +151,7 @@ for the type. The maximum value of ``BTF_INT_BITS()`` is 128.
The ``BTF_INT_OFFSET()`` specifies the starting bit offset to calculate values The ``BTF_INT_OFFSET()`` specifies the starting bit offset to calculate values
for this int. For example, a bitfield struct member has: for this int. For example, a bitfield struct member has:
* btf member bit offset 100 from the start of the structure, * btf member bit offset 100 from the start of the structure,
* btf member pointing to an int type, * btf member pointing to an int type,
* the int type has ``BTF_INT_OFFSET() = 2`` and ``BTF_INT_BITS() = 4`` * the int type has ``BTF_INT_OFFSET() = 2`` and ``BTF_INT_BITS() = 4``
@ -160,6 +161,7 @@ from bits ``100 + 2 = 102``.
Alternatively, the bitfield struct member can be the following to access the Alternatively, the bitfield struct member can be the following to access the
same bits as the above: same bits as the above:
* btf member bit offset 102, * btf member bit offset 102,
* btf member pointing to an int type, * btf member pointing to an int type,
* the int type has ``BTF_INT_OFFSET() = 0`` and ``BTF_INT_BITS() = 4`` * the int type has ``BTF_INT_OFFSET() = 0`` and ``BTF_INT_BITS() = 4``

21
Documentation/cdrom/Makefile
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@ -1,21 +0,0 @@
LATEXFILE = cdrom-standard
all:
make clean
latex $(LATEXFILE)
latex $(LATEXFILE)
@if [ -x `which gv` ]; then \
`dvips -q -t letter -o $(LATEXFILE).ps $(LATEXFILE).dvi` ;\
`gv -antialias -media letter -nocenter $(LATEXFILE).ps` ;\
else \
`xdvi $(LATEXFILE).dvi &` ;\
fi
make sortofclean
clean:
rm -f $(LATEXFILE).ps $(LATEXFILE).dvi $(LATEXFILE).aux $(LATEXFILE).log
sortofclean:
rm -f $(LATEXFILE).aux $(LATEXFILE).log

1063
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1026
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196
Documentation/cdrom/ide-cd → Documentation/cdrom/ide-cd.rst
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@ -1,18 +1,20 @@
IDE-CD driver documentation IDE-CD driver documentation
Originally by scott snyder <snyder@fnald0.fnal.gov> (19 May 1996) ===========================
Carrying on the torch is: Erik Andersen <andersee@debian.org>
New maintainers (19 Oct 1998): Jens Axboe <axboe@image.dk> :Originally by: scott snyder <snyder@fnald0.fnal.gov> (19 May 1996)
:Carrying on the torch is: Erik Andersen <andersee@debian.org>
:New maintainers (19 Oct 1998): Jens Axboe <axboe@image.dk>
1. Introduction 1. Introduction
--------------- ---------------
The ide-cd driver should work with all ATAPI ver 1.2 to ATAPI 2.6 compliant The ide-cd driver should work with all ATAPI ver 1.2 to ATAPI 2.6 compliant
CDROM drives which attach to an IDE interface. Note that some CDROM vendors CDROM drives which attach to an IDE interface. Note that some CDROM vendors
(including Mitsumi, Sony, Creative, Aztech, and Goldstar) have made (including Mitsumi, Sony, Creative, Aztech, and Goldstar) have made
both ATAPI-compliant drives and drives which use a proprietary both ATAPI-compliant drives and drives which use a proprietary
interface. If your drive uses one of those proprietary interfaces, interface. If your drive uses one of those proprietary interfaces,
this driver will not work with it (but one of the other CDROM drivers this driver will not work with it (but one of the other CDROM drivers
probably will). This driver will not work with `ATAPI' drives which probably will). This driver will not work with `ATAPI` drives which
attach to the parallel port. In addition, there is at least one drive attach to the parallel port. In addition, there is at least one drive
(CyCDROM CR520ie) which attaches to the IDE port but is not ATAPI; (CyCDROM CR520ie) which attaches to the IDE port but is not ATAPI;
this driver will not work with drives like that either (but see the this driver will not work with drives like that either (but see the
@ -31,7 +33,7 @@ This driver provides the following features:
from audio tracks. The program cdda2wav can be used for this. from audio tracks. The program cdda2wav can be used for this.
Note, however, that only some drives actually support this. Note, however, that only some drives actually support this.
- There is now support for CDROM changers which comply with the - There is now support for CDROM changers which comply with the
ATAPI 2.6 draft standard (such as the NEC CDR-251). This additional ATAPI 2.6 draft standard (such as the NEC CDR-251). This additional
functionality includes a function call to query which slot is the functionality includes a function call to query which slot is the
currently selected slot, a function call to query which slots contain currently selected slot, a function call to query which slots contain
@ -45,22 +47,22 @@ This driver provides the following features:
--------------- ---------------
0. The ide-cd relies on the ide disk driver. See 0. The ide-cd relies on the ide disk driver. See
Documentation/ide/ide.txt for up-to-date information on the ide Documentation/ide/ide.rst for up-to-date information on the ide
driver. driver.
1. Make sure that the ide and ide-cd drivers are compiled into the 1. Make sure that the ide and ide-cd drivers are compiled into the
kernel you're using. When configuring the kernel, in the section kernel you're using. When configuring the kernel, in the section
entitled "Floppy, IDE, and other block devices", say either `Y' entitled "Floppy, IDE, and other block devices", say either `Y`
(which will compile the support directly into the kernel) or `M' (which will compile the support directly into the kernel) or `M`
(to compile support as a module which can be loaded and unloaded) (to compile support as a module which can be loaded and unloaded)
to the options: to the options::
ATA/ATAPI/MFM/RLL support ATA/ATAPI/MFM/RLL support
Include IDE/ATAPI CDROM support Include IDE/ATAPI CDROM support
Depending on what type of IDE interface you have, you may need to Depending on what type of IDE interface you have, you may need to
specify additional configuration options. See specify additional configuration options. See
Documentation/ide/ide.txt. Documentation/ide/ide.rst.
2. You should also ensure that the iso9660 filesystem is either 2. You should also ensure that the iso9660 filesystem is either
compiled into the kernel or available as a loadable module. You compiled into the kernel or available as a loadable module. You
@ -72,35 +74,35 @@ This driver provides the following features:
address and an IRQ number, the standard assignments being address and an IRQ number, the standard assignments being
0x1f0 and 14 for the primary interface and 0x170 and 15 for the 0x1f0 and 14 for the primary interface and 0x170 and 15 for the
secondary interface. Each interface can control up to two devices, secondary interface. Each interface can control up to two devices,
where each device can be a hard drive, a CDROM drive, a floppy drive, where each device can be a hard drive, a CDROM drive, a floppy drive,
or a tape drive. The two devices on an interface are called `master' or a tape drive. The two devices on an interface are called `master`
and `slave'; this is usually selectable via a jumper on the drive. and `slave`; this is usually selectable via a jumper on the drive.
Linux names these devices as follows. The master and slave devices Linux names these devices as follows. The master and slave devices
on the primary IDE interface are called `hda' and `hdb', on the primary IDE interface are called `hda` and `hdb`,
respectively. The drives on the secondary interface are called respectively. The drives on the secondary interface are called
`hdc' and `hdd'. (Interfaces at other locations get other letters `hdc` and `hdd`. (Interfaces at other locations get other letters
in the third position; see Documentation/ide/ide.txt.) in the third position; see Documentation/ide/ide.rst.)
If you want your CDROM drive to be found automatically by the If you want your CDROM drive to be found automatically by the
driver, you should make sure your IDE interface uses either the driver, you should make sure your IDE interface uses either the
primary or secondary addresses mentioned above. In addition, if primary or secondary addresses mentioned above. In addition, if
the CDROM drive is the only device on the IDE interface, it should the CDROM drive is the only device on the IDE interface, it should
be jumpered as `master'. (If for some reason you cannot configure be jumpered as `master`. (If for some reason you cannot configure
your system in this manner, you can probably still use the driver. your system in this manner, you can probably still use the driver.
You may have to pass extra configuration information to the kernel You may have to pass extra configuration information to the kernel
when you boot, however. See Documentation/ide/ide.txt for more when you boot, however. See Documentation/ide/ide.rst for more
information.) information.)
4. Boot the system. If the drive is recognized, you should see a 4. Boot the system. If the drive is recognized, you should see a
message which looks like message which looks like::
hdb: NEC CD-ROM DRIVE:260, ATAPI CDROM drive hdb: NEC CD-ROM DRIVE:260, ATAPI CDROM drive
If you do not see this, see section 5 below. If you do not see this, see section 5 below.
5. You may want to create a symbolic link /dev/cdrom pointing to the 5. You may want to create a symbolic link /dev/cdrom pointing to the
actual device. You can do this with the command actual device. You can do this with the command::
ln -s /dev/hdX /dev/cdrom ln -s /dev/hdX /dev/cdrom
@ -108,14 +110,14 @@ This driver provides the following features:
drive is installed. drive is installed.
6. You should be able to see any error messages from the driver with 6. You should be able to see any error messages from the driver with
the `dmesg' command. the `dmesg` command.
3. Basic usage 3. Basic usage
-------------- --------------
An ISO 9660 CDROM can be mounted by putting the disc in the drive and An ISO 9660 CDROM can be mounted by putting the disc in the drive and
typing (as root) typing (as root)::
mount -t iso9660 /dev/cdrom /mnt/cdrom mount -t iso9660 /dev/cdrom /mnt/cdrom
@ -123,7 +125,7 @@ where it is assumed that /dev/cdrom is a link pointing to the actual
device (as described in step 5 of the last section) and /mnt/cdrom is device (as described in step 5 of the last section) and /mnt/cdrom is
an empty directory. You should now be able to see the contents of the an empty directory. You should now be able to see the contents of the
CDROM under the /mnt/cdrom directory. If you want to eject the CDROM, CDROM under the /mnt/cdrom directory. If you want to eject the CDROM,
you must first dismount it with a command like you must first dismount it with a command like::
umount /mnt/cdrom umount /mnt/cdrom
@ -148,7 +150,7 @@ such as cdda2wav. The only types of drive which I've heard support
this are Sony and Toshiba drives. You will get errors if you try to this are Sony and Toshiba drives. You will get errors if you try to
use this function on a drive which does not support it. use this function on a drive which does not support it.
For supported changers, you can use the `cdchange' program (appended to For supported changers, you can use the `cdchange` program (appended to
the end of this file) to switch between changer slots. Note that the the end of this file) to switch between changer slots. Note that the
drive should be unmounted before attempting this. The program takes drive should be unmounted before attempting this. The program takes
two arguments: the CDROM device, and the slot number to which you wish two arguments: the CDROM device, and the slot number to which you wish
@ -161,17 +163,17 @@ to change. If the slot number is -1, the drive is unloaded.
This section discusses some common problems encountered when trying to This section discusses some common problems encountered when trying to
use the driver, and some possible solutions. Note that if you are use the driver, and some possible solutions. Note that if you are
experiencing problems, you should probably also review experiencing problems, you should probably also review
Documentation/ide/ide.txt for current information about the underlying Documentation/ide/ide.rst for current information about the underlying
IDE support code. Some of these items apply only to earlier versions IDE support code. Some of these items apply only to earlier versions
of the driver, but are mentioned here for completeness. of the driver, but are mentioned here for completeness.
In most cases, you should probably check with `dmesg' for any errors In most cases, you should probably check with `dmesg` for any errors
from the driver. from the driver.
a. Drive is not detected during booting. a. Drive is not detected during booting.
- Review the configuration instructions above and in - Review the configuration instructions above and in
Documentation/ide/ide.txt, and check how your hardware is Documentation/ide/ide.rst, and check how your hardware is
configured. configured.
- If your drive is the only device on an IDE interface, it should - If your drive is the only device on an IDE interface, it should
@ -179,14 +181,14 @@ a. Drive is not detected during booting.
- If your IDE interface is not at the standard addresses of 0x170 - If your IDE interface is not at the standard addresses of 0x170
or 0x1f0, you'll need to explicitly inform the driver using a or 0x1f0, you'll need to explicitly inform the driver using a
lilo option. See Documentation/ide/ide.txt. (This feature was lilo option. See Documentation/ide/ide.rst. (This feature was
added around kernel version 1.3.30.) added around kernel version 1.3.30.)
- If the autoprobing is not finding your drive, you can tell the - If the autoprobing is not finding your drive, you can tell the
driver to assume that one exists by using a lilo option of the driver to assume that one exists by using a lilo option of the
form `hdX=cdrom', where X is the drive letter corresponding to form `hdX=cdrom`, where X is the drive letter corresponding to
where your drive is installed. Note that if you do this and you where your drive is installed. Note that if you do this and you
see a boot message like see a boot message like::
hdX: ATAPI cdrom (?) hdX: ATAPI cdrom (?)
@ -205,7 +207,7 @@ a. Drive is not detected during booting.
Support for some interfaces needing extra initialization is Support for some interfaces needing extra initialization is
provided in later 1.3.x kernels. You may need to turn on provided in later 1.3.x kernels. You may need to turn on
additional kernel configuration options to get them to work; additional kernel configuration options to get them to work;
see Documentation/ide/ide.txt. see Documentation/ide/ide.rst.
Even if support is not available for your interface, you may be Even if support is not available for your interface, you may be
able to get it to work with the following procedure. First boot able to get it to work with the following procedure. First boot
@ -220,7 +222,7 @@ b. Timeout/IRQ errors.
probably not making it to the host. probably not making it to the host.
- IRQ problems may also be indicated by the message - IRQ problems may also be indicated by the message
`IRQ probe failed (<n>)' while booting. If <n> is zero, that `IRQ probe failed (<n>)` while booting. If <n> is zero, that
means that the system did not see an interrupt from the drive when means that the system did not see an interrupt from the drive when
it was expecting one (on any feasible IRQ). If <n> is negative, it was expecting one (on any feasible IRQ). If <n> is negative,
that means the system saw interrupts on multiple IRQ lines, when that means the system saw interrupts on multiple IRQ lines, when
@ -240,27 +242,27 @@ b. Timeout/IRQ errors.
there are hardware problems with the interrupt setup; they there are hardware problems with the interrupt setup; they
apparently don't use interrupts. apparently don't use interrupts.
- If you own a Pioneer DR-A24X, you _will_ get nasty error messages - If you own a Pioneer DR-A24X, you _will_ get nasty error messages
on boot such as "irq timeout: status=0x50 { DriveReady SeekComplete }" on boot such as "irq timeout: status=0x50 { DriveReady SeekComplete }"
The Pioneer DR-A24X CDROM drives are fairly popular these days. The Pioneer DR-A24X CDROM drives are fairly popular these days.
Unfortunately, these drives seem to become very confused when we perform Unfortunately, these drives seem to become very confused when we perform
the standard Linux ATA disk drive probe. If you own one of these drives, the standard Linux ATA disk drive probe. If you own one of these drives,
you can bypass the ATA probing which confuses these CDROM drives, by you can bypass the ATA probing which confuses these CDROM drives, by
adding `append="hdX=noprobe hdX=cdrom"' to your lilo.conf file and running adding `append="hdX=noprobe hdX=cdrom"` to your lilo.conf file and running
lilo (again where X is the drive letter corresponding to where your drive lilo (again where X is the drive letter corresponding to where your drive
is installed.) is installed.)
c. System hangups. c. System hangups.
- If the system locks up when you try to access the CDROM, the most - If the system locks up when you try to access the CDROM, the most
likely cause is that you have a buggy IDE adapter which doesn't likely cause is that you have a buggy IDE adapter which doesn't
properly handle simultaneous transactions on multiple interfaces. properly handle simultaneous transactions on multiple interfaces.
The most notorious of these is the CMD640B chip. This problem can The most notorious of these is the CMD640B chip. This problem can
be worked around by specifying the `serialize' option when be worked around by specifying the `serialize` option when
booting. Recent kernels should be able to detect the need for booting. Recent kernels should be able to detect the need for
this automatically in most cases, but the detection is not this automatically in most cases, but the detection is not
foolproof. See Documentation/ide/ide.txt for more information foolproof. See Documentation/ide/ide.rst for more information
about the `serialize' option and the CMD640B. about the `serialize` option and the CMD640B.
- Note that many MS-DOS CDROM drivers will work with such buggy - Note that many MS-DOS CDROM drivers will work with such buggy
hardware, apparently because they never attempt to overlap CDROM hardware, apparently because they never attempt to overlap CDROM
@ -269,14 +271,14 @@ c. System hangups.
d. Can't mount a CDROM. d. Can't mount a CDROM.
- If you get errors from mount, it may help to check `dmesg' to see - If you get errors from mount, it may help to check `dmesg` to see
if there are any more specific errors from the driver or from the if there are any more specific errors from the driver or from the
filesystem. filesystem.
- Make sure there's a CDROM loaded in the drive, and that's it's an - Make sure there's a CDROM loaded in the drive, and that's it's an
ISO 9660 disc. You can't mount an audio CD. ISO 9660 disc. You can't mount an audio CD.
- With the CDROM in the drive and unmounted, try something like - With the CDROM in the drive and unmounted, try something like::
cat /dev/cdrom | od | more cat /dev/cdrom | od | more
@ -284,9 +286,9 @@ d. Can't mount a CDROM.
OK, and the problem is at the filesystem level (i.e., the CDROM is OK, and the problem is at the filesystem level (i.e., the CDROM is
not ISO 9660 or has errors in the filesystem structure). not ISO 9660 or has errors in the filesystem structure).
- If you see `not a block device' errors, check that the definitions - If you see `not a block device` errors, check that the definitions
of the device special files are correct. They should be as of the device special files are correct. They should be as
follows: follows::
brw-rw---- 1 root disk 3, 0 Nov 11 18:48 /dev/hda brw-rw---- 1 root disk 3, 0 Nov 11 18:48 /dev/hda
brw-rw---- 1 root disk 3, 64 Nov 11 18:48 /dev/hdb brw-rw---- 1 root disk 3, 64 Nov 11 18:48 /dev/hdb
@ -301,7 +303,7 @@ d. Can't mount a CDROM.
If you have a /dev/cdrom symbolic link, check that it is pointing If you have a /dev/cdrom symbolic link, check that it is pointing
to the correct device file. to the correct device file.
If you hear people talking of the devices `hd1a' and `hd1b', these If you hear people talking of the devices `hd1a` and `hd1b`, these
were old names for what are now called hdc and hdd. Those names were old names for what are now called hdc and hdd. Those names
should be considered obsolete. should be considered obsolete.
@ -311,8 +313,8 @@ d. Can't mount a CDROM.
always give meaningful error messages. always give meaningful error messages.
e. Directory listings are unpredictably truncated, and `dmesg' shows e. Directory listings are unpredictably truncated, and `dmesg` shows
`buffer botch' error messages from the driver. `buffer botch` error messages from the driver.
- There was a bug in the version of the driver in 1.2.x kernels - There was a bug in the version of the driver in 1.2.x kernels
which could cause this. It was fixed in 1.3.0. If you can't which could cause this. It was fixed in 1.3.0. If you can't
@ -335,34 +337,36 @@ f. Data corruption.
5. cdchange.c 5. cdchange.c
------------- -------------
/* ::
* cdchange.c [-v] <device> [<slot>]
*
* This loads a CDROM from a specified slot in a changer, and displays
* information about the changer status. The drive should be unmounted before
* using this program.
*
* Changer information is displayed if either the -v flag is specified
* or no slot was specified.
*
* Based on code originally from Gerhard Zuber <zuber@berlin.snafu.de>.
* Changer status information, and rewrite for the new Uniform CDROM driver
* interface by Erik Andersen <andersee@debian.org>.
*/
#include <stdio.h> /*
#include <stdlib.h> * cdchange.c [-v] <device> [<slot>]
#include <errno.h> *
#include <string.h> * This loads a CDROM from a specified slot in a changer, and displays
#include <unistd.h> * information about the changer status. The drive should be unmounted before
#include <fcntl.h> * using this program.
#include <sys/ioctl.h> *
#include <linux/cdrom.h> * Changer information is displayed if either the -v flag is specified
* or no slot was specified.
*
* Based on code originally from Gerhard Zuber <zuber@berlin.snafu.de>.
* Changer status information, and rewrite for the new Uniform CDROM driver
* interface by Erik Andersen <andersee@debian.org>.
*/
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/cdrom.h>
int int
main (int argc, char **argv) main (int argc, char **argv)
{ {
char *program; char *program;
char *device; char *device;
int fd; /* file descriptor for CD-ROM device */ int fd; /* file descriptor for CD-ROM device */
@ -382,30 +386,30 @@ main (int argc, char **argv)
fprintf (stderr, " Slots are numbered 1 -- n.\n"); fprintf (stderr, " Slots are numbered 1 -- n.\n");
exit (1); exit (1);
} }
if (strcmp (argv[0], "-v") == 0) { if (strcmp (argv[0], "-v") == 0) {
verbose = 1; verbose = 1;
++argv; ++argv;
--argc; --argc;
} }
device = argv[0]; device = argv[0];
if (argc == 2) if (argc == 2)
slot = atoi (argv[1]) - 1; slot = atoi (argv[1]) - 1;
/* open device */ /* open device */
fd = open(device, O_RDONLY | O_NONBLOCK); fd = open(device, O_RDONLY | O_NONBLOCK);
if (fd < 0) { if (fd < 0) {
fprintf (stderr, "%s: open failed for `%s': %s\n", fprintf (stderr, "%s: open failed for `%s`: %s\n",
program, device, strerror (errno)); program, device, strerror (errno));
exit (1); exit (1);
} }
/* Check CD player status */ /* Check CD player status */
total_slots_available = ioctl (fd, CDROM_CHANGER_NSLOTS); total_slots_available = ioctl (fd, CDROM_CHANGER_NSLOTS);
if (total_slots_available <= 1 ) { if (total_slots_available <= 1 ) {
fprintf (stderr, "%s: Device `%s' is not an ATAPI " fprintf (stderr, "%s: Device `%s` is not an ATAPI "
"compliant CD changer.\n", program, device); "compliant CD changer.\n", program, device);
exit (1); exit (1);
} }
@ -418,7 +422,7 @@ main (int argc, char **argv)
exit (1); exit (1);
} }
/* load */ /* load */
slot=ioctl (fd, CDROM_SELECT_DISC, slot); slot=ioctl (fd, CDROM_SELECT_DISC, slot);
if (slot<0) { if (slot<0) {
fflush(stdout); fflush(stdout);
@ -462,14 +466,14 @@ main (int argc, char **argv)
for (x_slot=0; x_slot<total_slots_available; x_slot++) { for (x_slot=0; x_slot<total_slots_available; x_slot++) {
printf ("Slot %2d: ", x_slot+1); printf ("Slot %2d: ", x_slot+1);
status = ioctl (fd, CDROM_DRIVE_STATUS, x_slot); status = ioctl (fd, CDROM_DRIVE_STATUS, x_slot);
if (status<0) { if (status<0) {
perror(" CDROM_DRIVE_STATUS"); perror(" CDROM_DRIVE_STATUS");
} else switch(status) { } else switch(status) {
case CDS_DISC_OK: case CDS_DISC_OK:
printf ("Disc present."); printf ("Disc present.");
break; break;
case CDS_NO_DISC: case CDS_NO_DISC:
printf ("Empty slot."); printf ("Empty slot.");
break; break;
case CDS_TRAY_OPEN: case CDS_TRAY_OPEN:
@ -507,11 +511,11 @@ main (int argc, char **argv)
break; break;
} }
} }
status = ioctl (fd, CDROM_MEDIA_CHANGED, x_slot); status = ioctl (fd, CDROM_MEDIA_CHANGED, x_slot);
if (status<0) { if (status<0) {
perror(" CDROM_MEDIA_CHANGED"); perror(" CDROM_MEDIA_CHANGED");
} }
switch (status) { switch (status) {
case 1: case 1:
printf ("Changed.\n"); printf ("Changed.\n");
break; break;
@ -525,10 +529,10 @@ main (int argc, char **argv)
/* close device */ /* close device */
status = close (fd); status = close (fd);
if (status != 0) { if (status != 0) {
fprintf (stderr, "%s: close failed for `%s': %s\n", fprintf (stderr, "%s: close failed for `%s`: %s\n",
program, device, strerror (errno)); program, device, strerror (errno));
exit (1); exit (1);
} }
exit (0); exit (0);
} }

19
Documentation/cdrom/index.rst Normal file
View File

@ -0,0 +1,19 @@
:orphan:
=====
cdrom
=====
.. toctree::
:maxdepth: 1
cdrom-standard
ide-cd
packet-writing
.. only:: subproject and html
Indices
=======
* :ref:`genindex`

27
Documentation/cdrom/packet-writing.txt → Documentation/cdrom/packet-writing.rst
View File

@ -1,3 +1,7 @@
==============
Packet writing
==============
Getting started quick Getting started quick
--------------------- ---------------------
@ -10,13 +14,16 @@ Getting started quick
Download from http://sourceforge.net/projects/linux-udf/ Download from http://sourceforge.net/projects/linux-udf/
- Grab a new CD-RW disc and format it (assuming CD-RW is hdc, substitute - Grab a new CD-RW disc and format it (assuming CD-RW is hdc, substitute
as appropriate): as appropriate)::
# cdrwtool -d /dev/hdc -q # cdrwtool -d /dev/hdc -q
- Setup your writer - Setup your writer::
# pktsetup dev_name /dev/hdc # pktsetup dev_name /dev/hdc
- Now you can mount /dev/pktcdvd/dev_name and copy files to it. Enjoy! - Now you can mount /dev/pktcdvd/dev_name and copy files to it. Enjoy::
# mount /dev/pktcdvd/dev_name /cdrom -t udf -o rw,noatime # mount /dev/pktcdvd/dev_name /cdrom -t udf -o rw,noatime
@ -25,11 +32,11 @@ Packet writing for DVD-RW media
DVD-RW discs can be written to much like CD-RW discs if they are in DVD-RW discs can be written to much like CD-RW discs if they are in
the so called "restricted overwrite" mode. To put a disc in restricted the so called "restricted overwrite" mode. To put a disc in restricted
overwrite mode, run: overwrite mode, run::
# dvd+rw-format /dev/hdc # dvd+rw-format /dev/hdc
You can then use the disc the same way you would use a CD-RW disc: You can then use the disc the same way you would use a CD-RW disc::
# pktsetup dev_name /dev/hdc # pktsetup dev_name /dev/hdc
# mount /dev/pktcdvd/dev_name /cdrom -t udf -o rw,noatime # mount /dev/pktcdvd/dev_name /cdrom -t udf -o rw,noatime
@ -41,7 +48,7 @@ Packet writing for DVD+RW media
According to the DVD+RW specification, a drive supporting DVD+RW discs According to the DVD+RW specification, a drive supporting DVD+RW discs
shall implement "true random writes with 2KB granularity", which means shall implement "true random writes with 2KB granularity", which means
that it should be possible to put any filesystem with a block size >= that it should be possible to put any filesystem with a block size >=
2KB on such a disc. For example, it should be possible to do: 2KB on such a disc. For example, it should be possible to do::
# dvd+rw-format /dev/hdc (only needed if the disc has never # dvd+rw-format /dev/hdc (only needed if the disc has never
been formatted) been formatted)
@ -54,7 +61,7 @@ follow the specification, but suffer bad performance problems if the
writes are not 32KB aligned. writes are not 32KB aligned.
Both problems can be solved by using the pktcdvd driver, which always Both problems can be solved by using the pktcdvd driver, which always
generates aligned writes. generates aligned writes::
# dvd+rw-format /dev/hdc # dvd+rw-format /dev/hdc
# pktsetup dev_name /dev/hdc # pktsetup dev_name /dev/hdc
@ -83,7 +90,7 @@ Notes
- Since the pktcdvd driver makes the disc appear as a regular block - Since the pktcdvd driver makes the disc appear as a regular block
device with a 2KB block size, you can put any filesystem you like on device with a 2KB block size, you can put any filesystem you like on
the disc. For example, run: the disc. For example, run::
# /sbin/mke2fs /dev/pktcdvd/dev_name # /sbin/mke2fs /dev/pktcdvd/dev_name
@ -97,7 +104,7 @@ Since Linux 2.6.20, the pktcdvd module has a sysfs interface
and can be controlled by it. For example the "pktcdvd" tool uses and can be controlled by it. For example the "pktcdvd" tool uses
this interface. (see http://tom.ist-im-web.de/download/pktcdvd ) this interface. (see http://tom.ist-im-web.de/download/pktcdvd )
"pktcdvd" works similar to "pktsetup", e.g.: "pktcdvd" works similar to "pktsetup", e.g.::
# pktcdvd -a dev_name /dev/hdc # pktcdvd -a dev_name /dev/hdc
# mkudffs /dev/pktcdvd/dev_name # mkudffs /dev/pktcdvd/dev_name
@ -115,7 +122,7 @@ For a description of the sysfs interface look into the file:
Using the pktcdvd debugfs interface Using the pktcdvd debugfs interface
----------------------------------- -----------------------------------
To read pktcdvd device infos in human readable form, do: To read pktcdvd device infos in human readable form, do::
# cat /sys/kernel/debug/pktcdvd/pktcdvd[0-7]/info # cat /sys/kernel/debug/pktcdvd/pktcdvd[0-7]/info

5
Documentation/conf.py
View File

@ -34,7 +34,8 @@ needs_sphinx = '1.3'
# Add any Sphinx extension module names here, as strings. They can be # Add any Sphinx extension module names here, as strings. They can be
# extensions coming with Sphinx (named 'sphinx.ext.*') or your custom # extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
# ones. # ones.
extensions = ['kerneldoc', 'rstFlatTable', 'kernel_include', 'cdomain', 'kfigure', 'sphinx.ext.ifconfig'] extensions = ['kerneldoc', 'rstFlatTable', 'kernel_include', 'cdomain',
'kfigure', 'sphinx.ext.ifconfig', 'automarkup']
# The name of the math extension changed on Sphinx 1.4 # The name of the math extension changed on Sphinx 1.4
if (major == 1 and minor > 3) or (major > 1): if (major == 1 and minor > 3) or (major > 1):
@ -200,7 +201,7 @@ html_context = {
# If true, SmartyPants will be used to convert quotes and dashes to # If true, SmartyPants will be used to convert quotes and dashes to
# typographically correct entities. # typographically correct entities.
#html_use_smartypants = True html_use_smartypants = False
# Custom sidebar templates, maps document names to template names. # Custom sidebar templates, maps document names to template names.
#html_sidebars = {} #html_sidebars = {}

2
Documentation/core-api/index.rst
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@ -34,6 +34,8 @@ Core utilities
timekeeping timekeeping
boot-time-mm boot-time-mm
memory-hotplug memory-hotplug
protection-keys
../RCU/index
Interfaces for kernel debugging Interfaces for kernel debugging

14
Documentation/core-api/kernel-api.rst
View File

@ -33,6 +33,9 @@ String Conversions
.. kernel-doc:: lib/kstrtox.c .. kernel-doc:: lib/kstrtox.c
:export: :export:
.. kernel-doc:: lib/string_helpers.c
:export:
String Manipulation String Manipulation
------------------- -------------------
@ -138,6 +141,15 @@ Base 2 log and power Functions
.. kernel-doc:: include/linux/log2.h .. kernel-doc:: include/linux/log2.h
:internal: :internal:
Integer power Functions
-----------------------
.. kernel-doc:: lib/math/int_pow.c
:export:
.. kernel-doc:: lib/math/int_sqrt.c
:export:
Division Functions Division Functions
------------------ ------------------
@ -358,8 +370,6 @@ Read-Copy Update (RCU)
.. kernel-doc:: kernel/rcu/tree.c .. kernel-doc:: kernel/rcu/tree.c
.. kernel-doc:: kernel/rcu/tree_plugin.h
.. kernel-doc:: kernel/rcu/tree_exp.h .. kernel-doc:: kernel/rcu/tree_exp.h
.. kernel-doc:: kernel/rcu/update.c .. kernel-doc:: kernel/rcu/update.c

0
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2
Documentation/core-api/timekeeping.rst
View File

@ -115,7 +115,7 @@ Some additional variants exist for more specialized cases:
void ktime_get_coarse_clocktai_ts64( struct timespec64 * ) void ktime_get_coarse_clocktai_ts64( struct timespec64 * )
These are quicker than the non-coarse versions, but less accurate, These are quicker than the non-coarse versions, but less accurate,
corresponding to CLOCK_MONONOTNIC_COARSE and CLOCK_REALTIME_COARSE corresponding to CLOCK_MONOTONIC_COARSE and CLOCK_REALTIME_COARSE
in user space, along with the equivalent boottime/tai/raw in user space, along with the equivalent boottime/tai/raw
timebase not available in user space. timebase not available in user space.

270
Documentation/core-api/xarray.rst
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@ -30,27 +30,27 @@ it called marks. Each mark may be set or cleared independently of
the others. You can iterate over entries which are marked. the others. You can iterate over entries which are marked.
Normal pointers may be stored in the XArray directly. They must be 4-byte Normal pointers may be stored in the XArray directly. They must be 4-byte
aligned, which is true for any pointer returned from :c:func:`kmalloc` and aligned, which is true for any pointer returned from kmalloc() and
:c:func:`alloc_page`. It isn't true for arbitrary user-space pointers, alloc_page(). It isn't true for arbitrary user-space pointers,
nor for function pointers. You can store pointers to statically allocated nor for function pointers. You can store pointers to statically allocated
objects, as long as those objects have an alignment of at least 4. objects, as long as those objects have an alignment of at least 4.
You can also store integers between 0 and ``LONG_MAX`` in the XArray. You can also store integers between 0 and ``LONG_MAX`` in the XArray.
You must first convert it into an entry using :c:func:`xa_mk_value`. You must first convert it into an entry using xa_mk_value().
When you retrieve an entry from the XArray, you can check whether it is When you retrieve an entry from the XArray, you can check whether it is
a value entry by calling :c:func:`xa_is_value`, and convert it back to a value entry by calling xa_is_value(), and convert it back to
an integer by calling :c:func:`xa_to_value`. an integer by calling xa_to_value().
Some users want to store tagged pointers instead of using the marks Some users want to store tagged pointers instead of using the marks
described above. They can call :c:func:`xa_tag_pointer` to create an described above. They can call xa_tag_pointer() to create an
entry with a tag, :c:func:`xa_untag_pointer` to turn a tagged entry entry with a tag, xa_untag_pointer() to turn a tagged entry
back into an untagged pointer and :c:func:`xa_pointer_tag` to retrieve back into an untagged pointer and xa_pointer_tag() to retrieve
the tag of an entry. Tagged pointers use the same bits that are used the tag of an entry. Tagged pointers use the same bits that are used
to distinguish value entries from normal pointers, so each user must to distinguish value entries from normal pointers, so each user must
decide whether they want to store value entries or tagged pointers in decide whether they want to store value entries or tagged pointers in
any particular XArray. any particular XArray.
The XArray does not support storing :c:func:`IS_ERR` pointers as some The XArray does not support storing IS_ERR() pointers as some
conflict with value entries or internal entries. conflict with value entries or internal entries.
An unusual feature of the XArray is the ability to create entries which An unusual feature of the XArray is the ability to create entries which
@ -64,89 +64,89 @@ entry will cause the XArray to forget about the range.
Normal API Normal API
========== ==========
Start by initialising an XArray, either with :c:func:`DEFINE_XARRAY` Start by initialising an XArray, either with DEFINE_XARRAY()
for statically allocated XArrays or :c:func:`xa_init` for dynamically for statically allocated XArrays or xa_init() for dynamically
allocated ones. A freshly-initialised XArray contains a ``NULL`` allocated ones. A freshly-initialised XArray contains a ``NULL``
pointer at every index. pointer at every index.
You can then set entries using :c:func:`xa_store` and get entries You can then set entries using xa_store() and get entries
using :c:func:`xa_load`. xa_store will overwrite any entry with the using xa_load(). xa_store will overwrite any entry with the
new entry and return the previous entry stored at that index. You can new entry and return the previous entry stored at that index. You can
use :c:func:`xa_erase` instead of calling :c:func:`xa_store` with a use xa_erase() instead of calling xa_store() with a
``NULL`` entry. There is no difference between an entry that has never ``NULL`` entry. There is no difference between an entry that has never
been stored to, one that has been erased and one that has most recently been stored to, one that has been erased and one that has most recently
had ``NULL`` stored to it. had ``NULL`` stored to it.
You can conditionally replace an entry at an index by using You can conditionally replace an entry at an index by using
:c:func:`xa_cmpxchg`. Like :c:func:`cmpxchg`, it will only succeed if xa_cmpxchg(). Like cmpxchg(), it will only succeed if
the entry at that index has the 'old' value. It also returns the entry the entry at that index has the 'old' value. It also returns the entry
which was at that index; if it returns the same entry which was passed as which was at that index; if it returns the same entry which was passed as
'old', then :c:func:`xa_cmpxchg` succeeded. 'old', then xa_cmpxchg() succeeded.
If you want to only store a new entry to an index if the current entry If you want to only store a new entry to an index if the current entry
at that index is ``NULL``, you can use :c:func:`xa_insert` which at that index is ``NULL``, you can use xa_insert() which
returns ``-EBUSY`` if the entry is not empty. returns ``-EBUSY`` if the entry is not empty.
You can enquire whether a mark is set on an entry by using You can enquire whether a mark is set on an entry by using
:c:func:`xa_get_mark`. If the entry is not ``NULL``, you can set a mark xa_get_mark(). If the entry is not ``NULL``, you can set a mark
on it by using :c:func:`xa_set_mark` and remove the mark from an entry by on it by using xa_set_mark() and remove the mark from an entry by
calling :c:func:`xa_clear_mark`. You can ask whether any entry in the calling xa_clear_mark(). You can ask whether any entry in the
XArray has a particular mark set by calling :c:func:`xa_marked`. XArray has a particular mark set by calling xa_marked().
You can copy entries out of the XArray into a plain array by calling You can copy entries out of the XArray into a plain array by calling
:c:func:`xa_extract`. Or you can iterate over the present entries in xa_extract(). Or you can iterate over the present entries in
the XArray by calling :c:func:`xa_for_each`. You may prefer to use the XArray by calling xa_for_each(). You may prefer to use
:c:func:`xa_find` or :c:func:`xa_find_after` to move to the next present xa_find() or xa_find_after() to move to the next present
entry in the XArray. entry in the XArray.
Calling :c:func:`xa_store_range` stores the same entry in a range Calling xa_store_range() stores the same entry in a range
of indices. If you do this, some of the other operations will behave of indices. If you do this, some of the other operations will behave
in a slightly odd way. For example, marking the entry at one index in a slightly odd way. For example, marking the entry at one index
may result in the entry being marked at some, but not all of the other may result in the entry being marked at some, but not all of the other
indices. Storing into one index may result in the entry retrieved by indices. Storing into one index may result in the entry retrieved by
some, but not all of the other indices changing. some, but not all of the other indices changing.
Sometimes you need to ensure that a subsequent call to :c:func:`xa_store` Sometimes you need to ensure that a subsequent call to xa_store()
will not need to allocate memory. The :c:func:`xa_reserve` function will not need to allocate memory. The xa_reserve() function
will store a reserved entry at the indicated index. Users of the will store a reserved entry at the indicated index. Users of the
normal API will see this entry as containing ``NULL``. If you do normal API will see this entry as containing ``NULL``. If you do
not need to use the reserved entry, you can call :c:func:`xa_release` not need to use the reserved entry, you can call xa_release()
to remove the unused entry. If another user has stored to the entry to remove the unused entry. If another user has stored to the entry
in the meantime, :c:func:`xa_release` will do nothing; if instead you in the meantime, xa_release() will do nothing; if instead you
want the entry to become ``NULL``, you should use :c:func:`xa_erase`. want the entry to become ``NULL``, you should use xa_erase().
Using :c:func:`xa_insert` on a reserved entry will fail. Using xa_insert() on a reserved entry will fail.
If all entries in the array are ``NULL``, the :c:func:`xa_empty` function If all entries in the array are ``NULL``, the xa_empty() function
will return ``true``. will return ``true``.
Finally, you can remove all entries from an XArray by calling Finally, you can remove all entries from an XArray by calling
:c:func:`xa_destroy`. If the XArray entries are pointers, you may wish xa_destroy(). If the XArray entries are pointers, you may wish
to free the entries first. You can do this by iterating over all present to free the entries first. You can do this by iterating over all present
entries in the XArray using the :c:func:`xa_for_each` iterator. entries in the XArray using the xa_for_each() iterator.
Allocating XArrays Allocating XArrays
------------------ ------------------
If you use :c:func:`DEFINE_XARRAY_ALLOC` to define the XArray, or If you use DEFINE_XARRAY_ALLOC() to define the XArray, or
initialise it by passing ``XA_FLAGS_ALLOC`` to :c:func:`xa_init_flags`, initialise it by passing ``XA_FLAGS_ALLOC`` to xa_init_flags(),
the XArray changes to track whether entries are in use or not. the XArray changes to track whether entries are in use or not.
You can call :c:func:`xa_alloc` to store the entry at an unused index You can call xa_alloc() to store the entry at an unused index
in the XArray. If you need to modify the array from interrupt context, in the XArray. If you need to modify the array from interrupt context,
you can use :c:func:`xa_alloc_bh` or :c:func:`xa_alloc_irq` to disable you can use xa_alloc_bh() or xa_alloc_irq() to disable
interrupts while allocating the ID. interrupts while allocating the ID.
Using :c:func:`xa_store`, :c:func:`xa_cmpxchg` or :c:func:`xa_insert` will Using xa_store(), xa_cmpxchg() or xa_insert() will
also mark the entry as being allocated. Unlike a normal XArray, storing also mark the entry as being allocated. Unlike a normal XArray, storing
``NULL`` will mark the entry as being in use, like :c:func:`xa_reserve`. ``NULL`` will mark the entry as being in use, like xa_reserve().
To free an entry, use :c:func:`xa_erase` (or :c:func:`xa_release` if To free an entry, use xa_erase() (or xa_release() if
you only want to free the entry if it's ``NULL``). you only want to free the entry if it's ``NULL``).
By default, the lowest free entry is allocated starting from 0. If you By default, the lowest free entry is allocated starting from 0. If you
want to allocate entries starting at 1, it is more efficient to use want to allocate entries starting at 1, it is more efficient to use
:c:func:`DEFINE_XARRAY_ALLOC1` or ``XA_FLAGS_ALLOC1``. If you want to DEFINE_XARRAY_ALLOC1() or ``XA_FLAGS_ALLOC1``. If you want to
allocate IDs up to a maximum, then wrap back around to the lowest free allocate IDs up to a maximum, then wrap back around to the lowest free
ID, you can use :c:func:`xa_alloc_cyclic`. ID, you can use xa_alloc_cyclic().
You cannot use ``XA_MARK_0`` with an allocating XArray as this mark You cannot use ``XA_MARK_0`` with an allocating XArray as this mark
is used to track whether an entry is free or not. The other marks are is used to track whether an entry is free or not. The other marks are
@ -155,17 +155,17 @@ available for your use.
Memory allocation Memory allocation
----------------- -----------------
The :c:func:`xa_store`, :c:func:`xa_cmpxchg`, :c:func:`xa_alloc`, The xa_store(), xa_cmpxchg(), xa_alloc(),
:c:func:`xa_reserve` and :c:func:`xa_insert` functions take a gfp_t xa_reserve() and xa_insert() functions take a gfp_t
parameter in case the XArray needs to allocate memory to store this entry. parameter in case the XArray needs to allocate memory to store this entry.
If the entry is being deleted, no memory allocation needs to be performed, If the entry is being deleted, no memory allocation needs to be performed,
and the GFP flags specified will be ignored. and the GFP flags specified will be ignored.
It is possible for no memory to be allocatable, particularly if you pass It is possible for no memory to be allocatable, particularly if you pass
a restrictive set of GFP flags. In that case, the functions return a a restrictive set of GFP flags. In that case, the functions return a
special value which can be turned into an errno using :c:func:`xa_err`. special value which can be turned into an errno using xa_err().
If you don't need to know exactly which error occurred, using If you don't need to know exactly which error occurred, using
:c:func:`xa_is_err` is slightly more efficient. xa_is_err() is slightly more efficient.
Locking Locking
------- -------
@ -174,54 +174,54 @@ When using the Normal API, you do not have to worry about locking.
The XArray uses RCU and an internal spinlock to synchronise access: The XArray uses RCU and an internal spinlock to synchronise access:
No lock needed: No lock needed:
* :c:func:`xa_empty` * xa_empty()
* :c:func:`xa_marked` * xa_marked()
Takes RCU read lock: Takes RCU read lock:
* :c:func:`xa_load` * xa_load()
* :c:func:`xa_for_each` * xa_for_each()
* :c:func:`xa_find` * xa_find()
* :c:func:`xa_find_after` * xa_find_after()
* :c:func:`xa_extract` * xa_extract()
* :c:func:`xa_get_mark` * xa_get_mark()
Takes xa_lock internally: Takes xa_lock internally:
* :c:func:`xa_store` * xa_store()
* :c:func:`xa_store_bh` * xa_store_bh()
* :c:func:`xa_store_irq` * xa_store_irq()
* :c:func:`xa_insert` * xa_insert()
* :c:func:`xa_insert_bh` * xa_insert_bh()
* :c:func:`xa_insert_irq` * xa_insert_irq()
* :c:func:`xa_erase` * xa_erase()
* :c:func:`xa_erase_bh` * xa_erase_bh()
* :c:func:`xa_erase_irq` * xa_erase_irq()
* :c:func:`xa_cmpxchg` * xa_cmpxchg()
* :c:func:`xa_cmpxchg_bh` * xa_cmpxchg_bh()
* :c:func:`xa_cmpxchg_irq` * xa_cmpxchg_irq()
* :c:func:`xa_store_range` * xa_store_range()
* :c:func:`xa_alloc` * xa_alloc()
* :c:func:`xa_alloc_bh` * xa_alloc_bh()
* :c:func:`xa_alloc_irq` * xa_alloc_irq()
* :c:func:`xa_reserve` * xa_reserve()
* :c:func:`xa_reserve_bh` * xa_reserve_bh()
* :c:func:`xa_reserve_irq` * xa_reserve_irq()
* :c:func:`xa_destroy` * xa_destroy()
* :c:func:`xa_set_mark` * xa_set_mark()
* :c:func:`xa_clear_mark` * xa_clear_mark()
Assumes xa_lock held on entry: Assumes xa_lock held on entry:
* :c:func:`__xa_store` * __xa_store()
* :c:func:`__xa_insert` * __xa_insert()
* :c:func:`__xa_erase` * __xa_erase()
* :c:func:`__xa_cmpxchg` * __xa_cmpxchg()
* :c:func:`__xa_alloc` * __xa_alloc()
* :c:func:`__xa_set_mark` * __xa_set_mark()
* :c:func:`__xa_clear_mark` * __xa_clear_mark()
If you want to take advantage of the lock to protect the data structures If you want to take advantage of the lock to protect the data structures
that you are storing in the XArray, you can call :c:func:`xa_lock` that you are storing in the XArray, you can call xa_lock()
before calling :c:func:`xa_load`, then take a reference count on the before calling xa_load(), then take a reference count on the
object you have found before calling :c:func:`xa_unlock`. This will object you have found before calling xa_unlock(). This will
prevent stores from removing the object from the array between looking prevent stores from removing the object from the array between looking
up the object and incrementing the refcount. You can also use RCU to up the object and incrementing the refcount. You can also use RCU to
avoid dereferencing freed memory, but an explanation of that is beyond avoid dereferencing freed memory, but an explanation of that is beyond
@ -261,7 +261,7 @@ context and then erase them in softirq context, you can do that this way::
} }
If you are going to modify the XArray from interrupt or softirq context, If you are going to modify the XArray from interrupt or softirq context,
you need to initialise the array using :c:func:`xa_init_flags`, passing you need to initialise the array using xa_init_flags(), passing
``XA_FLAGS_LOCK_IRQ`` or ``XA_FLAGS_LOCK_BH``. ``XA_FLAGS_LOCK_IRQ`` or ``XA_FLAGS_LOCK_BH``.
The above example also shows a common pattern of wanting to extend the The above example also shows a common pattern of wanting to extend the
@ -269,20 +269,20 @@ coverage of the xa_lock on the store side to protect some statistics
associated with the array. associated with the array.
Sharing the XArray with interrupt context is also possible, either Sharing the XArray with interrupt context is also possible, either
using :c:func:`xa_lock_irqsave` in both the interrupt handler and process using xa_lock_irqsave() in both the interrupt handler and process
context, or :c:func:`xa_lock_irq` in process context and :c:func:`xa_lock` context, or xa_lock_irq() in process context and xa_lock()
in the interrupt handler. Some of the more common patterns have helper in the interrupt handler. Some of the more common patterns have helper
functions such as :c:func:`xa_store_bh`, :c:func:`xa_store_irq`, functions such as xa_store_bh(), xa_store_irq(),
:c:func:`xa_erase_bh`, :c:func:`xa_erase_irq`, :c:func:`xa_cmpxchg_bh` xa_erase_bh(), xa_erase_irq(), xa_cmpxchg_bh()
and :c:func:`xa_cmpxchg_irq`. and xa_cmpxchg_irq().
Sometimes you need to protect access to the XArray with a mutex because Sometimes you need to protect access to the XArray with a mutex because
that lock sits above another mutex in the locking hierarchy. That does that lock sits above another mutex in the locking hierarchy. That does
not entitle you to use functions like :c:func:`__xa_erase` without taking not entitle you to use functions like __xa_erase() without taking
the xa_lock; the xa_lock is used for lockdep validation and will be used the xa_lock; the xa_lock is used for lockdep validation and will be used
for other purposes in the future. for other purposes in the future.
The :c:func:`__xa_set_mark` and :c:func:`__xa_clear_mark` functions are also The __xa_set_mark() and __xa_clear_mark() functions are also
available for situations where you look up an entry and want to atomically available for situations where you look up an entry and want to atomically
set or clear a mark. It may be more efficient to use the advanced API set or clear a mark. It may be more efficient to use the advanced API
in this case, as it will save you from walking the tree twice. in this case, as it will save you from walking the tree twice.
@ -300,27 +300,27 @@ indeed the normal API is implemented in terms of the advanced API. The
advanced API is only available to modules with a GPL-compatible license. advanced API is only available to modules with a GPL-compatible license.
The advanced API is based around the xa_state. This is an opaque data The advanced API is based around the xa_state. This is an opaque data
structure which you declare on the stack using the :c:func:`XA_STATE` structure which you declare on the stack using the XA_STATE()
macro. This macro initialises the xa_state ready to start walking macro. This macro initialises the xa_state ready to start walking
around the XArray. It is used as a cursor to maintain the position around the XArray. It is used as a cursor to maintain the position
in the XArray and let you compose various operations together without in the XArray and let you compose various operations together without
having to restart from the top every time. having to restart from the top every time.
The xa_state is also used to store errors. You can call The xa_state is also used to store errors. You can call
:c:func:`xas_error` to retrieve the error. All operations check whether xas_error() to retrieve the error. All operations check whether
the xa_state is in an error state before proceeding, so there's no need the xa_state is in an error state before proceeding, so there's no need
for you to check for an error after each call; you can make multiple for you to check for an error after each call; you can make multiple
calls in succession and only check at a convenient point. The only calls in succession and only check at a convenient point. The only
errors currently generated by the XArray code itself are ``ENOMEM`` and errors currently generated by the XArray code itself are ``ENOMEM`` and
``EINVAL``, but it supports arbitrary errors in case you want to call ``EINVAL``, but it supports arbitrary errors in case you want to call
:c:func:`xas_set_err` yourself. xas_set_err() yourself.
If the xa_state is holding an ``ENOMEM`` error, calling :c:func:`xas_nomem` If the xa_state is holding an ``ENOMEM`` error, calling xas_nomem()
will attempt to allocate more memory using the specified gfp flags and will attempt to allocate more memory using the specified gfp flags and
cache it in the xa_state for the next attempt. The idea is that you take cache it in the xa_state for the next attempt. The idea is that you take
the xa_lock, attempt the operation and drop the lock. The operation the xa_lock, attempt the operation and drop the lock. The operation
attempts to allocate memory while holding the lock, but it is more attempts to allocate memory while holding the lock, but it is more
likely to fail. Once you have dropped the lock, :c:func:`xas_nomem` likely to fail. Once you have dropped the lock, xas_nomem()
can try harder to allocate more memory. It will return ``true`` if it can try harder to allocate more memory. It will return ``true`` if it
is worth retrying the operation (i.e. that there was a memory error *and* is worth retrying the operation (i.e. that there was a memory error *and*
more memory was allocated). If it has previously allocated memory, and more memory was allocated). If it has previously allocated memory, and
@ -333,7 +333,7 @@ Internal Entries
The XArray reserves some entries for its own purposes. These are never The XArray reserves some entries for its own purposes. These are never
exposed through the normal API, but when using the advanced API, it's exposed through the normal API, but when using the advanced API, it's
possible to see them. Usually the best way to handle them is to pass them possible to see them. Usually the best way to handle them is to pass them
to :c:func:`xas_retry`, and retry the operation if it returns ``true``. to xas_retry(), and retry the operation if it returns ``true``.
.. flat-table:: .. flat-table::
:widths: 1 1 6 :widths: 1 1 6
@ -343,89 +343,89 @@ to :c:func:`xas_retry`, and retry the operation if it returns ``true``.
- Usage - Usage
* - Node * - Node
- :c:func:`xa_is_node` - xa_is_node()
- An XArray node. May be visible when using a multi-index xa_state. - An XArray node. May be visible when using a multi-index xa_state.
* - Sibling * - Sibling
- :c:func:`xa_is_sibling` - xa_is_sibling()
- A non-canonical entry for a multi-index entry. The value indicates - A non-canonical entry for a multi-index entry. The value indicates
which slot in this node has the canonical entry. which slot in this node has the canonical entry.
* - Retry * - Retry
- :c:func:`xa_is_retry` - xa_is_retry()
- This entry is currently being modified by a thread which has the - This entry is currently being modified by a thread which has the
xa_lock. The node containing this entry may be freed at the end xa_lock. The node containing this entry may be freed at the end
of this RCU period. You should restart the lookup from the head of this RCU period. You should restart the lookup from the head
of the array. of the array.
* - Zero * - Zero
- :c:func:`xa_is_zero` - xa_is_zero()
- Zero entries appear as ``NULL`` through the Normal API, but occupy - Zero entries appear as ``NULL`` through the Normal API, but occupy
an entry in the XArray which can be used to reserve the index for an entry in the XArray which can be used to reserve the index for
future use. This is used by allocating XArrays for allocated entries future use. This is used by allocating XArrays for allocated entries
which are ``NULL``. which are ``NULL``.
Other internal entries may be added in the future. As far as possible, they Other internal entries may be added in the future. As far as possible, they
will be handled by :c:func:`xas_retry`. will be handled by xas_retry().
Additional functionality Additional functionality
------------------------ ------------------------
The :c:func:`xas_create_range` function allocates all the necessary memory The xas_create_range() function allocates all the necessary memory
to store every entry in a range. It will set ENOMEM in the xa_state if to store every entry in a range. It will set ENOMEM in the xa_state if
it cannot allocate memory. it cannot allocate memory.
You can use :c:func:`xas_init_marks` to reset the marks on an entry You can use xas_init_marks() to reset the marks on an entry
to their default state. This is usually all marks clear, unless the to their default state. This is usually all marks clear, unless the
XArray is marked with ``XA_FLAGS_TRACK_FREE``, in which case mark 0 is set XArray is marked with ``XA_FLAGS_TRACK_FREE``, in which case mark 0 is set
and all other marks are clear. Replacing one entry with another using and all other marks are clear. Replacing one entry with another using
:c:func:`xas_store` will not reset the marks on that entry; if you want xas_store() will not reset the marks on that entry; if you want
the marks reset, you should do that explicitly. the marks reset, you should do that explicitly.
The :c:func:`xas_load` will walk the xa_state as close to the entry The xas_load() will walk the xa_state as close to the entry
as it can. If you know the xa_state has already been walked to the as it can. If you know the xa_state has already been walked to the
entry and need to check that the entry hasn't changed, you can use entry and need to check that the entry hasn't changed, you can use
:c:func:`xas_reload` to save a function call. xas_reload() to save a function call.
If you need to move to a different index in the XArray, call If you need to move to a different index in the XArray, call
:c:func:`xas_set`. This resets the cursor to the top of the tree, which xas_set(). This resets the cursor to the top of the tree, which
will generally make the next operation walk the cursor to the desired will generally make the next operation walk the cursor to the desired
spot in the tree. If you want to move to the next or previous index, spot in the tree. If you want to move to the next or previous index,
call :c:func:`xas_next` or :c:func:`xas_prev`. Setting the index does call xas_next() or xas_prev(). Setting the index does
not walk the cursor around the array so does not require a lock to be not walk the cursor around the array so does not require a lock to be
held, while moving to the next or previous index does. held, while moving to the next or previous index does.
You can search for the next present entry using :c:func:`xas_find`. This You can search for the next present entry using xas_find(). This
is the equivalent of both :c:func:`xa_find` and :c:func:`xa_find_after`; is the equivalent of both xa_find() and xa_find_after();
if the cursor has been walked to an entry, then it will find the next if the cursor has been walked to an entry, then it will find the next
entry after the one currently referenced. If not, it will return the entry after the one currently referenced. If not, it will return the
entry at the index of the xa_state. Using :c:func:`xas_next_entry` to entry at the index of the xa_state. Using xas_next_entry() to
move to the next present entry instead of :c:func:`xas_find` will save move to the next present entry instead of xas_find() will save
a function call in the majority of cases at the expense of emitting more a function call in the majority of cases at the expense of emitting more
inline code. inline code.
The :c:func:`xas_find_marked` function is similar. If the xa_state has The xas_find_marked() function is similar. If the xa_state has
not been walked, it will return the entry at the index of the xa_state, not been walked, it will return the entry at the index of the xa_state,
if it is marked. Otherwise, it will return the first marked entry after if it is marked. Otherwise, it will return the first marked entry after
the entry referenced by the xa_state. The :c:func:`xas_next_marked` the entry referenced by the xa_state. The xas_next_marked()
function is the equivalent of :c:func:`xas_next_entry`. function is the equivalent of xas_next_entry().
When iterating over a range of the XArray using :c:func:`xas_for_each` When iterating over a range of the XArray using xas_for_each()
or :c:func:`xas_for_each_marked`, it may be necessary to temporarily stop or xas_for_each_marked(), it may be necessary to temporarily stop
the iteration. The :c:func:`xas_pause` function exists for this purpose. the iteration. The xas_pause() function exists for this purpose.
After you have done the necessary work and wish to resume, the xa_state After you have done the necessary work and wish to resume, the xa_state
is in an appropriate state to continue the iteration after the entry is in an appropriate state to continue the iteration after the entry
you last processed. If you have interrupts disabled while iterating, you last processed. If you have interrupts disabled while iterating,
then it is good manners to pause the iteration and reenable interrupts then it is good manners to pause the iteration and reenable interrupts
every ``XA_CHECK_SCHED`` entries. every ``XA_CHECK_SCHED`` entries.
The :c:func:`xas_get_mark`, :c:func:`xas_set_mark` and The xas_get_mark(), xas_set_mark() and
:c:func:`xas_clear_mark` functions require the xa_state cursor to have xas_clear_mark() functions require the xa_state cursor to have
been moved to the appropriate location in the xarray; they will do been moved to the appropriate location in the xarray; they will do
nothing if you have called :c:func:`xas_pause` or :c:func:`xas_set` nothing if you have called xas_pause() or xas_set()
immediately before. immediately before.
You can call :c:func:`xas_set_update` to have a callback function You can call xas_set_update() to have a callback function
called each time the XArray updates a node. This is used by the page called each time the XArray updates a node. This is used by the page
cache workingset code to maintain its list of nodes which contain only cache workingset code to maintain its list of nodes which contain only
shadow entries. shadow entries.
@ -443,25 +443,25 @@ eg indices 64-127 may be tied together, but 2-6 may not be. This may
save substantial quantities of memory; for example tying 512 entries save substantial quantities of memory; for example tying 512 entries
together will save over 4kB. together will save over 4kB.
You can create a multi-index entry by using :c:func:`XA_STATE_ORDER` You can create a multi-index entry by using XA_STATE_ORDER()
or :c:func:`xas_set_order` followed by a call to :c:func:`xas_store`. or xas_set_order() followed by a call to xas_store().
Calling :c:func:`xas_load` with a multi-index xa_state will walk the Calling xas_load() with a multi-index xa_state will walk the
xa_state to the right location in the tree, but the return value is not xa_state to the right location in the tree, but the return value is not
meaningful, potentially being an internal entry or ``NULL`` even when there meaningful, potentially being an internal entry or ``NULL`` even when there
is an entry stored within the range. Calling :c:func:`xas_find_conflict` is an entry stored within the range. Calling xas_find_conflict()
will return the first entry within the range or ``NULL`` if there are no will return the first entry within the range or ``NULL`` if there are no
entries in the range. The :c:func:`xas_for_each_conflict` iterator will entries in the range. The xas_for_each_conflict() iterator will
iterate over every entry which overlaps the specified range. iterate over every entry which overlaps the specified range.
If :c:func:`xas_load` encounters a multi-index entry, the xa_index If xas_load() encounters a multi-index entry, the xa_index
in the xa_state will not be changed. When iterating over an XArray in the xa_state will not be changed. When iterating over an XArray
or calling :c:func:`xas_find`, if the initial index is in the middle or calling xas_find(), if the initial index is in the middle
of a multi-index entry, it will not be altered. Subsequent calls of a multi-index entry, it will not be altered. Subsequent calls
or iterations will move the index to the first index in the range. or iterations will move the index to the first index in the range.
Each entry will only be returned once, no matter how many indices it Each entry will only be returned once, no matter how many indices it
occupies. occupies.
Using :c:func:`xas_next` or :c:func:`xas_prev` with a multi-index xa_state Using xas_next() or xas_prev() with a multi-index xa_state
is not supported. Using either of these functions on a multi-index entry is not supported. Using either of these functions on a multi-index entry
will reveal sibling entries; these should be skipped over by the caller. will reveal sibling entries; these should be skipped over by the caller.

24
Documentation/device-mapper/cache-policies.txt → Documentation/device-mapper/cache-policies.rst
View File

@ -1,3 +1,4 @@
=============================
Guidance for writing policies Guidance for writing policies
============================= =============================
@ -30,7 +31,7 @@ multiqueue (mq)
This policy is now an alias for smq (see below). This policy is now an alias for smq (see below).
The following tunables are accepted, but have no effect: The following tunables are accepted, but have no effect::
'sequential_threshold <#nr_sequential_ios>' 'sequential_threshold <#nr_sequential_ios>'
'random_threshold <#nr_random_ios>' 'random_threshold <#nr_random_ios>'
@ -56,7 +57,9 @@ mq policy's hints to be dropped. Also, performance of the cache may
degrade slightly until smq recalculates the origin device's hotspots degrade slightly until smq recalculates the origin device's hotspots
that should be cached. that should be cached.
Memory usage: Memory usage
^^^^^^^^^^^^
The mq policy used a lot of memory; 88 bytes per cache block on a 64 The mq policy used a lot of memory; 88 bytes per cache block on a 64
bit machine. bit machine.
@ -69,7 +72,9 @@ cache block).
All this means smq uses ~25bytes per cache block. Still a lot of All this means smq uses ~25bytes per cache block. Still a lot of
memory, but a substantial improvement nontheless. memory, but a substantial improvement nontheless.
Level balancing: Level balancing
^^^^^^^^^^^^^^^
mq placed entries in different levels of the multiqueue structures mq placed entries in different levels of the multiqueue structures
based on their hit count (~ln(hit count)). This meant the bottom based on their hit count (~ln(hit count)). This meant the bottom
levels generally had the most entries, and the top ones had very levels generally had the most entries, and the top ones had very
@ -94,7 +99,9 @@ is used to decide which blocks to promote. If the hotspot queue is
performing badly then it starts moving entries more quickly between performing badly then it starts moving entries more quickly between
levels. This lets it adapt to new IO patterns very quickly. levels. This lets it adapt to new IO patterns very quickly.
Performance: Performance
^^^^^^^^^^^
Testing smq shows substantially better performance than mq. Testing smq shows substantially better performance than mq.
cleaner cleaner
@ -105,16 +112,19 @@ The cleaner writes back all dirty blocks in a cache to decommission it.
Examples Examples
======== ========
The syntax for a table is: The syntax for a table is::
cache <metadata dev> <cache dev> <origin dev> <block size> cache <metadata dev> <cache dev> <origin dev> <block size>
<#feature_args> [<feature arg>]* <#feature_args> [<feature arg>]*
<policy> <#policy_args> [<policy arg>]* <policy> <#policy_args> [<policy arg>]*
The syntax to send a message using the dmsetup command is: The syntax to send a message using the dmsetup command is::
dmsetup message <mapped device> 0 sequential_threshold 1024 dmsetup message <mapped device> 0 sequential_threshold 1024
dmsetup message <mapped device> 0 random_threshold 8 dmsetup message <mapped device> 0 random_threshold 8
Using dmsetup: Using dmsetup::
dmsetup create blah --table "0 268435456 cache /dev/sdb /dev/sdc \ dmsetup create blah --table "0 268435456 cache /dev/sdb /dev/sdc \
/dev/sdd 512 0 mq 4 sequential_threshold 1024 random_threshold 8" /dev/sdd 512 0 mq 4 sequential_threshold 1024 random_threshold 8"
creates a 128GB large mapped device named 'blah' with the creates a 128GB large mapped device named 'blah' with the

206
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@ -1,3 +1,7 @@
=====
Cache
=====
Introduction Introduction
============ ============
@ -24,10 +28,13 @@ scenarios (eg. a vm image server).
Glossary Glossary
======== ========
Migration - Movement of the primary copy of a logical block from one Migration
Movement of the primary copy of a logical block from one
device to the other. device to the other.
Promotion - Migration from slow device to fast device. Promotion
Demotion - Migration from fast device to slow device. Migration from slow device to fast device.
Demotion
Migration from fast device to slow device.
The origin device always contains a copy of the logical block, which The origin device always contains a copy of the logical block, which
may be out of date or kept in sync with the copy on the cache device may be out of date or kept in sync with the copy on the cache device
@ -169,45 +176,53 @@ Target interface
Constructor Constructor
----------- -----------
cache <metadata dev> <cache dev> <origin dev> <block size> ::
<#feature args> [<feature arg>]*
<policy> <#policy args> [policy args]*
metadata dev : fast device holding the persistent metadata cache <metadata dev> <cache dev> <origin dev> <block size>
cache dev : fast device holding cached data blocks <#feature args> [<feature arg>]*
origin dev : slow device holding original data blocks <policy> <#policy args> [policy args]*
block size : cache unit size in sectors
#feature args : number of feature arguments passed ================ =======================================================
feature args : writethrough or passthrough (The default is writeback.) metadata dev fast device holding the persistent metadata
cache dev fast device holding cached data blocks
origin dev slow device holding original data blocks
block size cache unit size in sectors
policy : the replacement policy to use #feature args number of feature arguments passed
#policy args : an even number of arguments corresponding to feature args writethrough or passthrough (The default is writeback.)
key/value pairs passed to the policy
policy args : key/value pairs passed to the policy policy the replacement policy to use
E.g. 'sequential_threshold 1024' #policy args an even number of arguments corresponding to
See cache-policies.txt for details. key/value pairs passed to the policy
policy args key/value pairs passed to the policy
E.g. 'sequential_threshold 1024'
See cache-policies.txt for details.
================ =======================================================
Optional feature arguments are: Optional feature arguments are:
writethrough : write through caching that prohibits cache block
content from being different from origin block content.
Without this argument, the default behaviour is to write
back cache block contents later for performance reasons,
so they may differ from the corresponding origin blocks.
passthrough : a degraded mode useful for various cache coherency
situations (e.g., rolling back snapshots of
underlying storage). Reads and writes always go to
the origin. If a write goes to a cached origin
block, then the cache block is invalidated.
To enable passthrough mode the cache must be clean.
metadata2 : use version 2 of the metadata. This stores the dirty bits ==================== ========================================================
in a separate btree, which improves speed of shutting writethrough write through caching that prohibits cache block
down the cache. content from being different from origin block content.
Without this argument, the default behaviour is to write
back cache block contents later for performance reasons,
so they may differ from the corresponding origin blocks.
no_discard_passdown : disable passing down discards from the cache passthrough a degraded mode useful for various cache coherency
to the origin's data device. situations (e.g., rolling back snapshots of
underlying storage). Reads and writes always go to
the origin. If a write goes to a cached origin
block, then the cache block is invalidated.
To enable passthrough mode the cache must be clean.
metadata2 use version 2 of the metadata. This stores the dirty
bits in a separate btree, which improves speed of
shutting down the cache.
no_discard_passdown disable passing down discards from the cache
to the origin's data device.
==================== ========================================================
A policy called 'default' is always registered. This is an alias for A policy called 'default' is always registered. This is an alias for
the policy we currently think is giving best all round performance. the policy we currently think is giving best all round performance.
@ -218,54 +233,61 @@ the characteristics of a specific policy, always request it by name.
Status Status
------ ------
<metadata block size> <#used metadata blocks>/<#total metadata blocks> ::
<cache block size> <#used cache blocks>/<#total cache blocks>
<#read hits> <#read misses> <#write hits> <#write misses>
<#demotions> <#promotions> <#dirty> <#features> <features>*
<#core args> <core args>* <policy name> <#policy args> <policy args>*
<cache metadata mode>
metadata block size : Fixed block size for each metadata block in <metadata block size> <#used metadata blocks>/<#total metadata blocks>
sectors <cache block size> <#used cache blocks>/<#total cache blocks>
#used metadata blocks : Number of metadata blocks used <#read hits> <#read misses> <#write hits> <#write misses>
#total metadata blocks : Total number of metadata blocks <#demotions> <#promotions> <#dirty> <#features> <features>*
cache block size : Configurable block size for the cache device <#core args> <core args>* <policy name> <#policy args> <policy args>*
in sectors <cache metadata mode>
#used cache blocks : Number of blocks resident in the cache
#total cache blocks : Total number of cache blocks
#read hits : Number of times a READ bio has been mapped ========================= =====================================================
to the cache metadata block size Fixed block size for each metadata block in
#read misses : Number of times a READ bio has been mapped sectors
to the origin #used metadata blocks Number of metadata blocks used
#write hits : Number of times a WRITE bio has been mapped #total metadata blocks Total number of metadata blocks
to the cache cache block size Configurable block size for the cache device
#write misses : Number of times a WRITE bio has been in sectors
mapped to the origin #used cache blocks Number of blocks resident in the cache
#demotions : Number of times a block has been removed #total cache blocks Total number of cache blocks
from the cache #read hits Number of times a READ bio has been mapped
#promotions : Number of times a block has been moved to to the cache
the cache #read misses Number of times a READ bio has been mapped
#dirty : Number of blocks in the cache that differ to the origin
from the origin #write hits Number of times a WRITE bio has been mapped
#feature args : Number of feature args to follow to the cache
feature args : 'writethrough' (optional) #write misses Number of times a WRITE bio has been
#core args : Number of core arguments (must be even) mapped to the origin
core args : Key/value pairs for tuning the core #demotions Number of times a block has been removed
e.g. migration_threshold from the cache
policy name : Name of the policy #promotions Number of times a block has been moved to
#policy args : Number of policy arguments to follow (must be even) the cache
policy args : Key/value pairs e.g. sequential_threshold #dirty Number of blocks in the cache that differ
cache metadata mode : ro if read-only, rw if read-write from the origin
In serious cases where even a read-only mode is deemed unsafe #feature args Number of feature args to follow
no further I/O will be permitted and the status will just feature args 'writethrough' (optional)
contain the string 'Fail'. The userspace recovery tools #core args Number of core arguments (must be even)
should then be used. core args Key/value pairs for tuning the core
needs_check : 'needs_check' if set, '-' if not set e.g. migration_threshold
A metadata operation has failed, resulting in the needs_check policy name Name of the policy
flag being set in the metadata's superblock. The metadata #policy args Number of policy arguments to follow (must be even)
device must be deactivated and checked/repaired before the policy args Key/value pairs e.g. sequential_threshold
cache can be made fully operational again. '-' indicates cache metadata mode ro if read-only, rw if read-write
needs_check is not set.
In serious cases where even a read-only mode is
deemed unsafe no further I/O will be permitted and
the status will just contain the string 'Fail'.
The userspace recovery tools should then be used.
needs_check 'needs_check' if set, '-' if not set
A metadata operation has failed, resulting in the
needs_check flag being set in the metadata's
superblock. The metadata device must be
deactivated and checked/repaired before the
cache can be made fully operational again.
'-' indicates needs_check is not set.
========================= =====================================================
Messages Messages
-------- --------
@ -274,11 +296,12 @@ Policies will have different tunables, specific to each one, so we
need a generic way of getting and setting these. Device-mapper need a generic way of getting and setting these. Device-mapper
messages are used. (A sysfs interface would also be possible.) messages are used. (A sysfs interface would also be possible.)
The message format is: The message format is::
<key> <value> <key> <value>
E.g. E.g.::
dmsetup message my_cache 0 sequential_threshold 1024 dmsetup message my_cache 0 sequential_threshold 1024
@ -290,11 +313,12 @@ of values from 5 to 9. Each cblock must be expressed as a decimal
value, in the future a variant message that takes cblock ranges value, in the future a variant message that takes cblock ranges
expressed in hexadecimal may be needed to better support efficient expressed in hexadecimal may be needed to better support efficient
invalidation of larger caches. The cache must be in passthrough mode invalidation of larger caches. The cache must be in passthrough mode
when invalidate_cblocks is used. when invalidate_cblocks is used::
invalidate_cblocks [<cblock>|<cblock begin>-<cblock end>]* invalidate_cblocks [<cblock>|<cblock begin>-<cblock end>]*
E.g. E.g.::
dmsetup message my_cache 0 invalidate_cblocks 2345 3456-4567 5678-6789 dmsetup message my_cache 0 invalidate_cblocks 2345 3456-4567 5678-6789
Examples Examples
@ -304,8 +328,10 @@ The test suite can be found here:
https://github.com/jthornber/device-mapper-test-suite https://github.com/jthornber/device-mapper-test-suite
dmsetup create my_cache --table '0 41943040 cache /dev/mapper/metadata \ ::
/dev/mapper/ssd /dev/mapper/origin 512 1 writeback default 0'
dmsetup create my_cache --table '0 41943040 cache /dev/mapper/metadata \ dmsetup create my_cache --table '0 41943040 cache /dev/mapper/metadata \
/dev/mapper/ssd /dev/mapper/origin 1024 1 writeback \ /dev/mapper/ssd /dev/mapper/origin 512 1 writeback default 0'
mq 4 sequential_threshold 1024 random_threshold 8' dmsetup create my_cache --table '0 41943040 cache /dev/mapper/metadata \
/dev/mapper/ssd /dev/mapper/origin 1024 1 writeback \
mq 4 sequential_threshold 1024 random_threshold 8'

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@ -1,10 +1,12 @@
========
dm-delay dm-delay
======== ========
Device-Mapper's "delay" target delays reads and/or writes Device-Mapper's "delay" target delays reads and/or writes
and maps them to different devices. and maps them to different devices.
Parameters: Parameters::
<device> <offset> <delay> [<write_device> <write_offset> <write_delay> <device> <offset> <delay> [<write_device> <write_offset> <write_delay>
[<flush_device> <flush_offset> <flush_delay>]] [<flush_device> <flush_offset> <flush_delay>]]
@ -14,15 +16,16 @@ Delays are specified in milliseconds.
Example scripts Example scripts
=============== ===============
[[
#!/bin/sh
# Create device delaying rw operation for 500ms
echo "0 `blockdev --getsz $1` delay $1 0 500" | dmsetup create delayed
]]
[[ ::
#!/bin/sh
# Create device delaying only write operation for 500ms and #!/bin/sh
# splitting reads and writes to different devices $1 $2 # Create device delaying rw operation for 500ms
echo "0 `blockdev --getsz $1` delay $1 0 0 $2 0 500" | dmsetup create delayed echo "0 `blockdev --getsz $1` delay $1 0 500" | dmsetup create delayed
]]
::
#!/bin/sh
# Create device delaying only write operation for 500ms and
# splitting reads and writes to different devices $1 $2
echo "0 `blockdev --getsz $1` delay $1 0 0 $2 0 500" | dmsetup create delayed

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@ -1,5 +1,6 @@
========
dm-crypt dm-crypt
========= ========
Device-Mapper's "crypt" target provides transparent encryption of block devices Device-Mapper's "crypt" target provides transparent encryption of block devices
using the kernel crypto API. using the kernel crypto API.
@ -7,15 +8,20 @@ using the kernel crypto API.
For a more detailed description of supported parameters see: For a more detailed description of supported parameters see:
https://gitlab.com/cryptsetup/cryptsetup/wikis/DMCrypt https://gitlab.com/cryptsetup/cryptsetup/wikis/DMCrypt
Parameters: <cipher> <key> <iv_offset> <device path> \ Parameters::
<cipher> <key> <iv_offset> <device path> \
<offset> [<#opt_params> <opt_params>] <offset> [<#opt_params> <opt_params>]
<cipher> <cipher>
Encryption cipher, encryption mode and Initial Vector (IV) generator. Encryption cipher, encryption mode and Initial Vector (IV) generator.
The cipher specifications format is: The cipher specifications format is::
cipher[:keycount]-chainmode-ivmode[:ivopts] cipher[:keycount]-chainmode-ivmode[:ivopts]
Examples:
Examples::
aes-cbc-essiv:sha256 aes-cbc-essiv:sha256
aes-xts-plain64 aes-xts-plain64
serpent-xts-plain64 serpent-xts-plain64
@ -25,12 +31,17 @@ Parameters: <cipher> <key> <iv_offset> <device path> \
as for the first format type. as for the first format type.
This format is mainly used for specification of authenticated modes. This format is mainly used for specification of authenticated modes.
The crypto API cipher specifications format is: The crypto API cipher specifications format is::
capi:cipher_api_spec-ivmode[:ivopts] capi:cipher_api_spec-ivmode[:ivopts]
Examples:
Examples::
capi:cbc(aes)-essiv:sha256 capi:cbc(aes)-essiv:sha256
capi:xts(aes)-plain64 capi:xts(aes)-plain64
Examples of authenticated modes:
Examples of authenticated modes::
capi:gcm(aes)-random capi:gcm(aes)-random
capi:authenc(hmac(sha256),xts(aes))-random capi:authenc(hmac(sha256),xts(aes))-random
capi:rfc7539(chacha20,poly1305)-random capi:rfc7539(chacha20,poly1305)-random
@ -142,21 +153,21 @@ LUKS (Linux Unified Key Setup) is now the preferred way to set up disk
encryption with dm-crypt using the 'cryptsetup' utility, see encryption with dm-crypt using the 'cryptsetup' utility, see
https://gitlab.com/cryptsetup/cryptsetup https://gitlab.com/cryptsetup/cryptsetup
[[ ::
#!/bin/sh
# Create a crypt device using dmsetup
dmsetup create crypt1 --table "0 `blockdev --getsz $1` crypt aes-cbc-essiv:sha256 babebabebabebabebabebabebabebabe 0 $1 0"
]]
[[ #!/bin/sh
#!/bin/sh # Create a crypt device using dmsetup
# Create a crypt device using dmsetup when encryption key is stored in keyring service dmsetup create crypt1 --table "0 `blockdev --getsz $1` crypt aes-cbc-essiv:sha256 babebabebabebabebabebabebabebabe 0 $1 0"
dmsetup create crypt2 --table "0 `blockdev --getsize $1` crypt aes-cbc-essiv:sha256 :32:logon:my_prefix:my_key 0 $1 0"
]]
[[ ::
#!/bin/sh
# Create a crypt device using cryptsetup and LUKS header with default cipher #!/bin/sh
cryptsetup luksFormat $1 # Create a crypt device using dmsetup when encryption key is stored in keyring service
cryptsetup luksOpen $1 crypt1 dmsetup create crypt2 --table "0 `blockdev --getsize $1` crypt aes-cbc-essiv:sha256 :32:logon:my_prefix:my_key 0 $1 0"
]]
::
#!/bin/sh
# Create a crypt device using cryptsetup and LUKS header with default cipher
cryptsetup luksFormat $1
cryptsetup luksOpen $1 crypt1

45
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@ -1,3 +1,4 @@
=========
dm-flakey dm-flakey
========= =========
@ -15,17 +16,26 @@ underlying devices.
Table parameters Table parameters
---------------- ----------------
::
<dev path> <offset> <up interval> <down interval> \ <dev path> <offset> <up interval> <down interval> \
[<num_features> [<feature arguments>]] [<num_features> [<feature arguments>]]
Mandatory parameters: Mandatory parameters:
<dev path>: Full pathname to the underlying block-device, or a
"major:minor" device-number. <dev path>:
<offset>: Starting sector within the device. Full pathname to the underlying block-device, or a
<up interval>: Number of seconds device is available. "major:minor" device-number.
<down interval>: Number of seconds device returns errors. <offset>:
Starting sector within the device.
<up interval>:
Number of seconds device is available.
<down interval>:
Number of seconds device returns errors.
Optional feature parameters: Optional feature parameters:
If no feature parameters are present, during the periods of If no feature parameters are present, during the periods of
unreliability, all I/O returns errors. unreliability, all I/O returns errors.
@ -41,17 +51,24 @@ Optional feature parameters:
During <down interval>, replace <Nth_byte> of the data of During <down interval>, replace <Nth_byte> of the data of
each matching bio with <value>. each matching bio with <value>.
<Nth_byte>: The offset of the byte to replace. <Nth_byte>:
Counting starts at 1, to replace the first byte. The offset of the byte to replace.
<direction>: Either 'r' to corrupt reads or 'w' to corrupt writes. Counting starts at 1, to replace the first byte.
'w' is incompatible with drop_writes. <direction>:
<value>: The value (from 0-255) to write. Either 'r' to corrupt reads or 'w' to corrupt writes.
<flags>: Perform the replacement only if bio->bi_opf has all the 'w' is incompatible with drop_writes.
selected flags set. <value>:
The value (from 0-255) to write.
<flags>:
Perform the replacement only if bio->bi_opf has all the
selected flags set.
Examples: Examples:
Replaces the 32nd byte of READ bios with the value 1::
corrupt_bio_byte 32 r 1 0 corrupt_bio_byte 32 r 1 0
- replaces the 32nd byte of READ bios with the value 1
Replaces the 224th byte of REQ_META (=32) bios with the value 0::
corrupt_bio_byte 224 w 0 32 corrupt_bio_byte 224 w 0 32
- replaces the 224th byte of REQ_META (=32) bios with the value 0

89
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@ -1,5 +1,6 @@
================================
Early creation of mapped devices Early creation of mapped devices
==================================== ================================
It is possible to configure a device-mapper device to act as the root device for It is possible to configure a device-mapper device to act as the root device for
your system in two ways. your system in two ways.
@ -12,15 +13,17 @@ The second is to create one or more device-mappers using the module parameter
The format is specified as a string of data separated by commas and optionally The format is specified as a string of data separated by commas and optionally
semi-colons, where: semi-colons, where:
- a comma is used to separate fields like name, uuid, flags and table - a comma is used to separate fields like name, uuid, flags and table
(specifies one device) (specifies one device)
- a semi-colon is used to separate devices. - a semi-colon is used to separate devices.
So the format will look like this: So the format will look like this::
dm-mod.create=<name>,<uuid>,<minor>,<flags>,<table>[,<table>+][;<name>,<uuid>,<minor>,<flags>,<table>[,<table>+]+] dm-mod.create=<name>,<uuid>,<minor>,<flags>,<table>[,<table>+][;<name>,<uuid>,<minor>,<flags>,<table>[,<table>+]+]
Where, Where::
<name> ::= The device name. <name> ::= The device name.
<uuid> ::= xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx | "" <uuid> ::= xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx | ""
<minor> ::= The device minor number | "" <minor> ::= The device minor number | ""
@ -29,7 +32,7 @@ Where,
<target_type> ::= "verity" | "linear" | ... (see list below) <target_type> ::= "verity" | "linear" | ... (see list below)
The dm line should be equivalent to the one used by the dmsetup tool with the The dm line should be equivalent to the one used by the dmsetup tool with the
--concise argument. `--concise` argument.
Target types Target types
============ ============
@ -38,32 +41,34 @@ Not all target types are available as there are serious risks in allowing
activation of certain DM targets without first using userspace tools to check activation of certain DM targets without first using userspace tools to check
the validity of associated metadata. the validity of associated metadata.
"cache": constrained, userspace should verify cache device ======================= =======================================================
"crypt": allowed `cache` constrained, userspace should verify cache device
"delay": allowed `crypt` allowed
"era": constrained, userspace should verify metadata device `delay` allowed
"flakey": constrained, meant for test `era` constrained, userspace should verify metadata device
"linear": allowed `flakey` constrained, meant for test
"log-writes": constrained, userspace should verify metadata device `linear` allowed
"mirror": constrained, userspace should verify main/mirror device `log-writes` constrained, userspace should verify metadata device
"raid": constrained, userspace should verify metadata device `mirror` constrained, userspace should verify main/mirror device
"snapshot": constrained, userspace should verify src/dst device `raid` constrained, userspace should verify metadata device
"snapshot-origin": allowed `snapshot` constrained, userspace should verify src/dst device
"snapshot-merge": constrained, userspace should verify src/dst device `snapshot-origin` allowed
"striped": allowed `snapshot-merge` constrained, userspace should verify src/dst device
"switch": constrained, userspace should verify dev path `striped` allowed
"thin": constrained, requires dm target message from userspace `switch` constrained, userspace should verify dev path
"thin-pool": constrained, requires dm target message from userspace `thin` constrained, requires dm target message from userspace
"verity": allowed `thin-pool` constrained, requires dm target message from userspace
"writecache": constrained, userspace should verify cache device `verity` allowed
"zero": constrained, not meant for rootfs `writecache` constrained, userspace should verify cache device
`zero` constrained, not meant for rootfs
======================= =======================================================
If the target is not listed above, it is constrained by default (not tested). If the target is not listed above, it is constrained by default (not tested).
Examples Examples
======== ========
An example of booting to a linear array made up of user-mode linux block An example of booting to a linear array made up of user-mode linux block
devices: devices::
dm-mod.create="lroot,,,rw, 0 4096 linear 98:16 0, 4096 4096 linear 98:32 0" root=/dev/dm-0 dm-mod.create="lroot,,,rw, 0 4096 linear 98:16 0, 4096 4096 linear 98:32 0" root=/dev/dm-0
@ -71,43 +76,49 @@ This will boot to a rw dm-linear target of 8192 sectors split across two block
devices identified by their major:minor numbers. After boot, udev will rename devices identified by their major:minor numbers. After boot, udev will rename
this target to /dev/mapper/lroot (depending on the rules). No uuid was assigned. this target to /dev/mapper/lroot (depending on the rules). No uuid was assigned.
An example of multiple device-mappers, with the dm-mod.create="..." contents is shown here An example of multiple device-mappers, with the dm-mod.create="..." contents
split on multiple lines for readability: is shown here split on multiple lines for readability::
vroot,,,ro, dm-linear,,1,rw,
0 1740800 verity 254:0 254:0 1740800 sha1 0 32768 linear 8:1 0,
76e9be054b15884a9fa85973e9cb274c93afadb6 32768 1024000 linear 8:2 0;
5b3549d54d6c7a3837b9b81ed72e49463a64c03680c47835bef94d768e5646fe; dm-verity,,3,ro,
vram,,,rw, 0 1638400 verity 1 /dev/sdc1 /dev/sdc2 4096 4096 204800 1 sha256
0 32768 linear 1:0 0, ac87db56303c9c1da433d7209b5a6ef3e4779df141200cbd7c157dcb8dd89c42
32768 32768 linear 1:1 0 5ebfe87f7df3235b80a117ebc4078e44f55045487ad4a96581d1adb564615b51
Other examples (per target): Other examples (per target):
"crypt": "crypt"::
dm-crypt,,8,ro, dm-crypt,,8,ro,
0 1048576 crypt aes-xts-plain64 0 1048576 crypt aes-xts-plain64
babebabebabebabebabebabebabebabebabebabebabebabebabebabebabebabe 0 babebabebabebabebabebabebabebabebabebabebabebabebabebabebabebabe 0
/dev/sda 0 1 allow_discards /dev/sda 0 1 allow_discards
"delay": "delay"::
dm-delay,,4,ro,0 409600 delay /dev/sda1 0 500 dm-delay,,4,ro,0 409600 delay /dev/sda1 0 500
"linear": "linear"::
dm-linear,,,rw, dm-linear,,,rw,
0 32768 linear /dev/sda1 0, 0 32768 linear /dev/sda1 0,
32768 1024000 linear /dev/sda2 0, 32768 1024000 linear /dev/sda2 0,
1056768 204800 linear /dev/sda3 0, 1056768 204800 linear /dev/sda3 0,
1261568 512000 linear /dev/sda4 0 1261568 512000 linear /dev/sda4 0
"snapshot-origin": "snapshot-origin"::
dm-snap-orig,,4,ro,0 409600 snapshot-origin 8:2 dm-snap-orig,,4,ro,0 409600 snapshot-origin 8:2
"striped": "striped"::
dm-striped,,4,ro,0 1638400 striped 4 4096 dm-striped,,4,ro,0 1638400 striped 4 4096
/dev/sda1 0 /dev/sda2 0 /dev/sda3 0 /dev/sda4 0 /dev/sda1 0 /dev/sda2 0 /dev/sda3 0 /dev/sda4 0
"verity": "verity"::
dm-verity,,4,ro, dm-verity,,4,ro,
0 1638400 verity 1 8:1 8:2 4096 4096 204800 1 sha256 0 1638400 verity 1 8:1 8:2 4096 4096 204800 1 sha256
fb1a5a0f00deb908d8b53cb270858975e76cf64105d412ce764225d53b8f3cfd fb1a5a0f00deb908d8b53cb270858975e76cf64105d412ce764225d53b8f3cfd

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@ -1,3 +1,7 @@
============
dm-integrity
============
The dm-integrity target emulates a block device that has additional The dm-integrity target emulates a block device that has additional
per-sector tags that can be used for storing integrity information. per-sector tags that can be used for storing integrity information.
@ -35,15 +39,16 @@ zeroes. If the superblock is neither valid nor zeroed, the dm-integrity
target can't be loaded. target can't be loaded.
To use the target for the first time: To use the target for the first time:
1. overwrite the superblock with zeroes 1. overwrite the superblock with zeroes
2. load the dm-integrity target with one-sector size, the kernel driver 2. load the dm-integrity target with one-sector size, the kernel driver
will format the device will format the device
3. unload the dm-integrity target 3. unload the dm-integrity target
4. read the "provided_data_sectors" value from the superblock 4. read the "provided_data_sectors" value from the superblock
5. load the dm-integrity target with the the target size 5. load the dm-integrity target with the the target size
"provided_data_sectors" "provided_data_sectors"
6. if you want to use dm-integrity with dm-crypt, load the dm-crypt target 6. if you want to use dm-integrity with dm-crypt, load the dm-crypt target
with the size "provided_data_sectors" with the size "provided_data_sectors"
Target arguments: Target arguments:
@ -51,17 +56,20 @@ Target arguments:
1. the underlying block device 1. the underlying block device
2. the number of reserved sector at the beginning of the device - the 2. the number of reserved sector at the beginning of the device - the
dm-integrity won't read of write these sectors dm-integrity won't read of write these sectors
3. the size of the integrity tag (if "-" is used, the size is taken from 3. the size of the integrity tag (if "-" is used, the size is taken from
the internal-hash algorithm) the internal-hash algorithm)
4. mode: 4. mode:
D - direct writes (without journal) - in this mode, journaling is
D - direct writes (without journal)
in this mode, journaling is
not used and data sectors and integrity tags are written not used and data sectors and integrity tags are written
separately. In case of crash, it is possible that the data separately. In case of crash, it is possible that the data
and integrity tag doesn't match. and integrity tag doesn't match.
J - journaled writes - data and integrity tags are written to the J - journaled writes
data and integrity tags are written to the
journal and atomicity is guaranteed. In case of crash, journal and atomicity is guaranteed. In case of crash,
either both data and tag or none of them are written. The either both data and tag or none of them are written. The
journaled mode degrades write throughput twice because the journaled mode degrades write throughput twice because the
@ -178,9 +186,12 @@ and the reloaded target would be non-functional.
The layout of the formatted block device: The layout of the formatted block device:
* reserved sectors (they are not used by this target, they can be used for
storing LUKS metadata or for other purpose), the size of the reserved * reserved sectors
area is specified in the target arguments (they are not used by this target, they can be used for
storing LUKS metadata or for other purpose), the size of the reserved
area is specified in the target arguments
* superblock (4kiB) * superblock (4kiB)
* magic string - identifies that the device was formatted * magic string - identifies that the device was formatted
* version * version
@ -192,40 +203,55 @@ The layout of the formatted block device:
metadata and padding). The user of this target should not send metadata and padding). The user of this target should not send
bios that access data beyond the "provided data sectors" limit. bios that access data beyond the "provided data sectors" limit.
* flags * flags
SB_FLAG_HAVE_JOURNAL_MAC - a flag is set if journal_mac is used SB_FLAG_HAVE_JOURNAL_MAC
SB_FLAG_RECALCULATING - recalculating is in progress - a flag is set if journal_mac is used
SB_FLAG_DIRTY_BITMAP - journal area contains the bitmap of dirty SB_FLAG_RECALCULATING
blocks - recalculating is in progress
SB_FLAG_DIRTY_BITMAP
- journal area contains the bitmap of dirty
blocks
* log2(sectors per block) * log2(sectors per block)
* a position where recalculating finished * a position where recalculating finished
* journal * journal
The journal is divided into sections, each section contains: The journal is divided into sections, each section contains:
* metadata area (4kiB), it contains journal entries * metadata area (4kiB), it contains journal entries
every journal entry contains:
- every journal entry contains:
* logical sector (specifies where the data and tag should * logical sector (specifies where the data and tag should
be written) be written)
* last 8 bytes of data * last 8 bytes of data
* integrity tag (the size is specified in the superblock) * integrity tag (the size is specified in the superblock)
every metadata sector ends with
- every metadata sector ends with
* mac (8-bytes), all the macs in 8 metadata sectors form a * mac (8-bytes), all the macs in 8 metadata sectors form a
64-byte value. It is used to store hmac of sector 64-byte value. It is used to store hmac of sector
numbers in the journal section, to protect against a numbers in the journal section, to protect against a
possibility that the attacker tampers with sector possibility that the attacker tampers with sector
numbers in the journal. numbers in the journal.
* commit id * commit id
* data area (the size is variable; it depends on how many journal * data area (the size is variable; it depends on how many journal
entries fit into the metadata area) entries fit into the metadata area)
every sector in the data area contains:
- every sector in the data area contains:
* data (504 bytes of data, the last 8 bytes are stored in * data (504 bytes of data, the last 8 bytes are stored in
the journal entry) the journal entry)
* commit id * commit id
To test if the whole journal section was written correctly, every To test if the whole journal section was written correctly, every
512-byte sector of the journal ends with 8-byte commit id. If the 512-byte sector of the journal ends with 8-byte commit id. If the
commit id matches on all sectors in a journal section, then it is commit id matches on all sectors in a journal section, then it is
assumed that the section was written correctly. If the commit id assumed that the section was written correctly. If the commit id
doesn't match, the section was written partially and it should not doesn't match, the section was written partially and it should not
be replayed. be replayed.
* one or more runs of interleaved tags and data. Each run contains:
* one or more runs of interleaved tags and data.
Each run contains:
* tag area - it contains integrity tags. There is one tag for each * tag area - it contains integrity tags. There is one tag for each
sector in the data area sector in the data area
* data area - it contains data sectors. The number of data sectors * data area - it contains data sectors. The number of data sectors

14
Documentation/device-mapper/dm-io.txt → Documentation/device-mapper/dm-io.rst
View File

@ -1,3 +1,4 @@
=====
dm-io dm-io
===== =====
@ -7,7 +8,7 @@ version.
The user must set up an io_region structure to describe the desired location The user must set up an io_region structure to describe the desired location
of the I/O. Each io_region indicates a block-device along with the starting of the I/O. Each io_region indicates a block-device along with the starting
sector and size of the region. sector and size of the region::
struct io_region { struct io_region {
struct block_device *bdev; struct block_device *bdev;
@ -19,7 +20,7 @@ Dm-io can read from one io_region or write to one or more io_regions. Writes
to multiple regions are specified by an array of io_region structures. to multiple regions are specified by an array of io_region structures.
The first I/O service type takes a list of memory pages as the data buffer for The first I/O service type takes a list of memory pages as the data buffer for
the I/O, along with an offset into the first page. the I/O, along with an offset into the first page::
struct page_list { struct page_list {
struct page_list *next; struct page_list *next;
@ -35,7 +36,7 @@ the I/O, along with an offset into the first page.
The second I/O service type takes an array of bio vectors as the data buffer The second I/O service type takes an array of bio vectors as the data buffer
for the I/O. This service can be handy if the caller has a pre-assembled bio, for the I/O. This service can be handy if the caller has a pre-assembled bio,
but wants to direct different portions of the bio to different devices. but wants to direct different portions of the bio to different devices::
int dm_io_sync_bvec(unsigned int num_regions, struct io_region *where, int dm_io_sync_bvec(unsigned int num_regions, struct io_region *where,
int rw, struct bio_vec *bvec, int rw, struct bio_vec *bvec,
@ -47,7 +48,7 @@ but wants to direct different portions of the bio to different devices.
The third I/O service type takes a pointer to a vmalloc'd memory buffer as the The third I/O service type takes a pointer to a vmalloc'd memory buffer as the
data buffer for the I/O. This service can be handy if the caller needs to do data buffer for the I/O. This service can be handy if the caller needs to do
I/O to a large region but doesn't want to allocate a large number of individual I/O to a large region but doesn't want to allocate a large number of individual
memory pages. memory pages::
int dm_io_sync_vm(unsigned int num_regions, struct io_region *where, int rw, int dm_io_sync_vm(unsigned int num_regions, struct io_region *where, int rw,
void *data, unsigned long *error_bits); void *data, unsigned long *error_bits);
@ -55,11 +56,11 @@ memory pages.
void *data, io_notify_fn fn, void *context); void *data, io_notify_fn fn, void *context);
Callers of the asynchronous I/O services must include the name of a completion Callers of the asynchronous I/O services must include the name of a completion
callback routine and a pointer to some context data for the I/O. callback routine and a pointer to some context data for the I/O::
typedef void (*io_notify_fn)(unsigned long error, void *context); typedef void (*io_notify_fn)(unsigned long error, void *context);
The "error" parameter in this callback, as well as the "*error" parameter in The "error" parameter in this callback, as well as the `*error` parameter in
all of the synchronous versions, is a bitset (instead of a simple error value). all of the synchronous versions, is a bitset (instead of a simple error value).
In the case of an write-I/O to multiple regions, this bitset allows dm-io to In the case of an write-I/O to multiple regions, this bitset allows dm-io to
indicate success or failure on each individual region. indicate success or failure on each individual region.
@ -72,4 +73,3 @@ always available in order to avoid unnecessary waiting while performing I/O.
When the user is finished using the dm-io services, they should call When the user is finished using the dm-io services, they should call
dm_io_put() and specify the same number of pages that were given on the dm_io_put() and specify the same number of pages that were given on the
dm_io_get() call. dm_io_get() call.

5
Documentation/device-mapper/dm-log.txt → Documentation/device-mapper/dm-log.rst
View File

@ -1,3 +1,4 @@
=====================
Device-Mapper Logging Device-Mapper Logging
===================== =====================
The device-mapper logging code is used by some of the device-mapper The device-mapper logging code is used by some of the device-mapper
@ -16,11 +17,13 @@ dm_dirty_log_type in include/linux/dm-dirty-log.h). Various different
logging implementations are available and provide different logging implementations are available and provide different
capabilities. The list includes: capabilities. The list includes:
============== ==============================================================
Type Files Type Files
==== ===== ============== ==============================================================
disk drivers/md/dm-log.c disk drivers/md/dm-log.c
core drivers/md/dm-log.c core drivers/md/dm-log.c
userspace drivers/md/dm-log-userspace* include/linux/dm-log-userspace.h userspace drivers/md/dm-log-userspace* include/linux/dm-log-userspace.h
============== ==============================================================
The "disk" log type The "disk" log type
------------------- -------------------

25
Documentation/device-mapper/dm-queue-length.txt → Documentation/device-mapper/dm-queue-length.rst
View File

@ -1,3 +1,4 @@
===============
dm-queue-length dm-queue-length
=============== ===============
@ -6,12 +7,18 @@ which selects a path with the least number of in-flight I/Os.
The path selector name is 'queue-length'. The path selector name is 'queue-length'.
Table parameters for each path: [<repeat_count>] Table parameters for each path: [<repeat_count>]
::
<repeat_count>: The number of I/Os to dispatch using the selected <repeat_count>: The number of I/Os to dispatch using the selected
path before switching to the next path. path before switching to the next path.
If not given, internal default is used. To check If not given, internal default is used. To check
the default value, see the activated table. the default value, see the activated table.
Status for each path: <status> <fail-count> <in-flight> Status for each path: <status> <fail-count> <in-flight>
::
<status>: 'A' if the path is active, 'F' if the path is failed. <status>: 'A' if the path is active, 'F' if the path is failed.
<fail-count>: The number of path failures. <fail-count>: The number of path failures.
<in-flight>: The number of in-flight I/Os on the path. <in-flight>: The number of in-flight I/Os on the path.
@ -29,11 +36,13 @@ Examples
======== ========
In case that 2 paths (sda and sdb) are used with repeat_count == 128. In case that 2 paths (sda and sdb) are used with repeat_count == 128.
# echo "0 10 multipath 0 0 1 1 queue-length 0 2 1 8:0 128 8:16 128" \ ::
dmsetup create test
# # echo "0 10 multipath 0 0 1 1 queue-length 0 2 1 8:0 128 8:16 128" \
# dmsetup table dmsetup create test
test: 0 10 multipath 0 0 1 1 queue-length 0 2 1 8:0 128 8:16 128 #
# # dmsetup table
# dmsetup status test: 0 10 multipath 0 0 1 1 queue-length 0 2 1 8:0 128 8:16 128
test: 0 10 multipath 2 0 0 0 1 1 E 0 2 1 8:0 A 0 0 8:16 A 0 0 #
# dmsetup status
test: 0 10 multipath 2 0 0 0 1 1 E 0 2 1 8:0 A 0 0 8:16 A 0 0

225
Documentation/device-mapper/dm-raid.txt → Documentation/device-mapper/dm-raid.rst
View File

@ -1,3 +1,4 @@
=======
dm-raid dm-raid
======= =======
@ -8,49 +9,66 @@ interface.
Mapping Table Interface Mapping Table Interface
----------------------- -----------------------
The target is named "raid" and it accepts the following parameters: The target is named "raid" and it accepts the following parameters::
<raid_type> <#raid_params> <raid_params> \ <raid_type> <#raid_params> <raid_params> \
<#raid_devs> <metadata_dev0> <dev0> [.. <metadata_devN> <devN>] <#raid_devs> <metadata_dev0> <dev0> [.. <metadata_devN> <devN>]
<raid_type>: <raid_type>:
============= ===============================================================
raid0 RAID0 striping (no resilience) raid0 RAID0 striping (no resilience)
raid1 RAID1 mirroring raid1 RAID1 mirroring
raid4 RAID4 with dedicated last parity disk raid4 RAID4 with dedicated last parity disk
raid5_n RAID5 with dedicated last parity disk supporting takeover raid5_n RAID5 with dedicated last parity disk supporting takeover
Same as raid4 Same as raid4
-Transitory layout
- Transitory layout
raid5_la RAID5 left asymmetric raid5_la RAID5 left asymmetric
- rotating parity 0 with data continuation - rotating parity 0 with data continuation
raid5_ra RAID5 right asymmetric raid5_ra RAID5 right asymmetric
- rotating parity N with data continuation - rotating parity N with data continuation
raid5_ls RAID5 left symmetric raid5_ls RAID5 left symmetric
- rotating parity 0 with data restart - rotating parity 0 with data restart
raid5_rs RAID5 right symmetric raid5_rs RAID5 right symmetric
- rotating parity N with data restart - rotating parity N with data restart
raid6_zr RAID6 zero restart raid6_zr RAID6 zero restart
- rotating parity zero (left-to-right) with data restart - rotating parity zero (left-to-right) with data restart
raid6_nr RAID6 N restart raid6_nr RAID6 N restart
- rotating parity N (right-to-left) with data restart - rotating parity N (right-to-left) with data restart
raid6_nc RAID6 N continue raid6_nc RAID6 N continue
- rotating parity N (right-to-left) with data continuation - rotating parity N (right-to-left) with data continuation
raid6_n_6 RAID6 with dedicate parity disks raid6_n_6 RAID6 with dedicate parity disks
- parity and Q-syndrome on the last 2 disks; - parity and Q-syndrome on the last 2 disks;
layout for takeover from/to raid4/raid5_n layout for takeover from/to raid4/raid5_n
raid6_la_6 Same as "raid_la" plus dedicated last Q-syndrome disk raid6_la_6 Same as "raid_la" plus dedicated last Q-syndrome disk
- layout for takeover from raid5_la from/to raid6 - layout for takeover from raid5_la from/to raid6
raid6_ra_6 Same as "raid5_ra" dedicated last Q-syndrome disk raid6_ra_6 Same as "raid5_ra" dedicated last Q-syndrome disk
- layout for takeover from raid5_ra from/to raid6 - layout for takeover from raid5_ra from/to raid6
raid6_ls_6 Same as "raid5_ls" dedicated last Q-syndrome disk raid6_ls_6 Same as "raid5_ls" dedicated last Q-syndrome disk
- layout for takeover from raid5_ls from/to raid6 - layout for takeover from raid5_ls from/to raid6
raid6_rs_6 Same as "raid5_rs" dedicated last Q-syndrome disk raid6_rs_6 Same as "raid5_rs" dedicated last Q-syndrome disk
- layout for takeover from raid5_rs from/to raid6 - layout for takeover from raid5_rs from/to raid6
raid10 Various RAID10 inspired algorithms chosen by additional params raid10 Various RAID10 inspired algorithms chosen by additional params
(see raid10_format and raid10_copies below) (see raid10_format and raid10_copies below)
- RAID10: Striped Mirrors (aka 'Striping on top of mirrors') - RAID10: Striped Mirrors (aka 'Striping on top of mirrors')
- RAID1E: Integrated Adjacent Stripe Mirroring - RAID1E: Integrated Adjacent Stripe Mirroring
- RAID1E: Integrated Offset Stripe Mirroring - RAID1E: Integrated Offset Stripe Mirroring
- and other similar RAID10 variants - and other similar RAID10 variants
============= ===============================================================
Reference: Chapter 4 of Reference: Chapter 4 of
http://www.snia.org/sites/default/files/SNIA_DDF_Technical_Position_v2.0.pdf http://www.snia.org/sites/default/files/SNIA_DDF_Technical_Position_v2.0.pdf
@ -58,33 +76,41 @@ The target is named "raid" and it accepts the following parameters:
<#raid_params>: The number of parameters that follow. <#raid_params>: The number of parameters that follow.
<raid_params> consists of <raid_params> consists of
Mandatory parameters: Mandatory parameters:
<chunk_size>: Chunk size in sectors. This parameter is often known as <chunk_size>:
Chunk size in sectors. This parameter is often known as
"stripe size". It is the only mandatory parameter and "stripe size". It is the only mandatory parameter and
is placed first. is placed first.
followed by optional parameters (in any order): followed by optional parameters (in any order):
[sync|nosync] Force or prevent RAID initialization. [sync|nosync]
Force or prevent RAID initialization.
[rebuild <idx>] Rebuild drive number 'idx' (first drive is 0). [rebuild <idx>]
Rebuild drive number 'idx' (first drive is 0).
[daemon_sleep <ms>] [daemon_sleep <ms>]
Interval between runs of the bitmap daemon that Interval between runs of the bitmap daemon that
clear bits. A longer interval means less bitmap I/O but clear bits. A longer interval means less bitmap I/O but
resyncing after a failure is likely to take longer. resyncing after a failure is likely to take longer.
[min_recovery_rate <kB/sec/disk>] Throttle RAID initialization [min_recovery_rate <kB/sec/disk>]
[max_recovery_rate <kB/sec/disk>] Throttle RAID initialization Throttle RAID initialization
[write_mostly <idx>] Mark drive index 'idx' write-mostly. [max_recovery_rate <kB/sec/disk>]
[max_write_behind <sectors>] See '--write-behind=' (man mdadm) Throttle RAID initialization
[stripe_cache <sectors>] Stripe cache size (RAID 4/5/6 only) [write_mostly <idx>]
Mark drive index 'idx' write-mostly.
[max_write_behind <sectors>]
See '--write-behind=' (man mdadm)
[stripe_cache <sectors>]
Stripe cache size (RAID 4/5/6 only)
[region_size <sectors>] [region_size <sectors>]
The region_size multiplied by the number of regions is the The region_size multiplied by the number of regions is the
logical size of the array. The bitmap records the device logical size of the array. The bitmap records the device
synchronisation state for each region. synchronisation state for each region.
[raid10_copies <# copies>] [raid10_copies <# copies>], [raid10_format <near|far|offset>]
[raid10_format <near|far|offset>]
These two options are used to alter the default layout of These two options are used to alter the default layout of
a RAID10 configuration. The number of copies is can be a RAID10 configuration. The number of copies is can be
specified, but the default is 2. There are also three specified, but the default is 2. There are also three
@ -93,13 +119,17 @@ The target is named "raid" and it accepts the following parameters:
respect to mirroring. If these options are left unspecified, respect to mirroring. If these options are left unspecified,
or 'raid10_copies 2' and/or 'raid10_format near' are given, or 'raid10_copies 2' and/or 'raid10_format near' are given,
then the layouts for 2, 3 and 4 devices are: then the layouts for 2, 3 and 4 devices are:
======== ========== ==============
2 drives 3 drives 4 drives 2 drives 3 drives 4 drives
-------- ---------- -------------- ======== ========== ==============
A1 A1 A1 A1 A2 A1 A1 A2 A2 A1 A1 A1 A1 A2 A1 A1 A2 A2
A2 A2 A2 A3 A3 A3 A3 A4 A4 A2 A2 A2 A3 A3 A3 A3 A4 A4
A3 A3 A4 A4 A5 A5 A5 A6 A6 A3 A3 A4 A4 A5 A5 A5 A6 A6
A4 A4 A5 A6 A6 A7 A7 A8 A8 A4 A4 A5 A6 A6 A7 A7 A8 A8
.. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. ..
======== ========== ==============
The 2-device layout is equivalent 2-way RAID1. The 4-device The 2-device layout is equivalent 2-way RAID1. The 4-device
layout is what a traditional RAID10 would look like. The layout is what a traditional RAID10 would look like. The
3-device layout is what might be called a 'RAID1E - Integrated 3-device layout is what might be called a 'RAID1E - Integrated
@ -107,8 +137,10 @@ The target is named "raid" and it accepts the following parameters:
If 'raid10_copies 2' and 'raid10_format far', then the layouts If 'raid10_copies 2' and 'raid10_format far', then the layouts
for 2, 3 and 4 devices are: for 2, 3 and 4 devices are:
======== ============ ===================
2 drives 3 drives 4 drives 2 drives 3 drives 4 drives
-------- -------------- -------------------- ======== ============ ===================
A1 A2 A1 A2 A3 A1 A2 A3 A4 A1 A2 A1 A2 A3 A1 A2 A3 A4
A3 A4 A4 A5 A6 A5 A6 A7 A8 A3 A4 A4 A5 A6 A5 A6 A7 A8
A5 A6 A7 A8 A9 A9 A10 A11 A12 A5 A6 A7 A8 A9 A9 A10 A11 A12
@ -117,11 +149,14 @@ The target is named "raid" and it accepts the following parameters:
A4 A3 A6 A4 A5 A6 A5 A8 A7 A4 A3 A6 A4 A5 A6 A5 A8 A7
A6 A5 A9 A7 A8 A10 A9 A12 A11 A6 A5 A9 A7 A8 A10 A9 A12 A11
.. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. ..
======== ============ ===================
If 'raid10_copies 2' and 'raid10_format offset', then the If 'raid10_copies 2' and 'raid10_format offset', then the
layouts for 2, 3 and 4 devices are: layouts for 2, 3 and 4 devices are:
======== ========== ================
2 drives 3 drives 4 drives 2 drives 3 drives 4 drives
-------- ------------ ----------------- ======== ========== ================
A1 A2 A1 A2 A3 A1 A2 A3 A4 A1 A2 A1 A2 A3 A1 A2 A3 A4
A2 A1 A3 A1 A2 A2 A1 A4 A3 A2 A1 A3 A1 A2 A2 A1 A4 A3
A3 A4 A4 A5 A6 A5 A6 A7 A8 A3 A4 A4 A5 A6 A5 A6 A7 A8
@ -129,6 +164,8 @@ The target is named "raid" and it accepts the following parameters:
A5 A6 A7 A8 A9 A9 A10 A11 A12 A5 A6 A7 A8 A9 A9 A10 A11 A12
A6 A5 A9 A7 A8 A10 A9 A12 A11 A6 A5 A9 A7 A8 A10 A9 A12 A11
.. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. ..
======== ========== ================
Here we see layouts closely akin to 'RAID1E - Integrated Here we see layouts closely akin to 'RAID1E - Integrated
Offset Stripe Mirroring'. Offset Stripe Mirroring'.
@ -190,22 +227,25 @@ The target is named "raid" and it accepts the following parameters:
Example Tables Example Tables
-------------- --------------
# RAID4 - 4 data drives, 1 parity (no metadata devices)
# No metadata devices specified to hold superblock/bitmap info
# Chunk size of 1MiB
# (Lines separated for easy reading)
0 1960893648 raid \ ::
raid4 1 2048 \
5 - 8:17 - 8:33 - 8:49 - 8:65 - 8:81
# RAID4 - 4 data drives, 1 parity (with metadata devices) # RAID4 - 4 data drives, 1 parity (no metadata devices)
# Chunk size of 1MiB, force RAID initialization, # No metadata devices specified to hold superblock/bitmap info
# min recovery rate at 20 kiB/sec/disk # Chunk size of 1MiB
# (Lines separated for easy reading)
0 1960893648 raid \ 0 1960893648 raid \
raid4 4 2048 sync min_recovery_rate 20 \ raid4 1 2048 \
5 8:17 8:18 8:33 8:34 8:49 8:50 8:65 8:66 8:81 8:82 5 - 8:17 - 8:33 - 8:49 - 8:65 - 8:81
# RAID4 - 4 data drives, 1 parity (with metadata devices)
# Chunk size of 1MiB, force RAID initialization,
# min recovery rate at 20 kiB/sec/disk
0 1960893648 raid \
raid4 4 2048 sync min_recovery_rate 20 \
5 8:17 8:18 8:33 8:34 8:49 8:50 8:65 8:66 8:81 8:82
Status Output Status Output
@ -219,41 +259,58 @@ Arguments that can be repeated are ordered by value.
'dmsetup status' yields information on the state and health of the array. 'dmsetup status' yields information on the state and health of the array.
The output is as follows (normally a single line, but expanded here for The output is as follows (normally a single line, but expanded here for
clarity): clarity)::
1: <s> <l> raid \
2: <raid_type> <#devices> <health_chars> \ 1: <s> <l> raid \
3: <sync_ratio> <sync_action> <mismatch_cnt> 2: <raid_type> <#devices> <health_chars> \
3: <sync_ratio> <sync_action> <mismatch_cnt>
Line 1 is the standard output produced by device-mapper. Line 1 is the standard output produced by device-mapper.
Line 2 & 3 are produced by the raid target and are best explained by example:
Line 2 & 3 are produced by the raid target and are best explained by example::
0 1960893648 raid raid4 5 AAAAA 2/490221568 init 0 0 1960893648 raid raid4 5 AAAAA 2/490221568 init 0
Here we can see the RAID type is raid4, there are 5 devices - all of Here we can see the RAID type is raid4, there are 5 devices - all of
which are 'A'live, and the array is 2/490221568 complete with its initial which are 'A'live, and the array is 2/490221568 complete with its initial
recovery. Here is a fuller description of the individual fields: recovery. Here is a fuller description of the individual fields:
=============== =========================================================
<raid_type> Same as the <raid_type> used to create the array. <raid_type> Same as the <raid_type> used to create the array.
<health_chars> One char for each device, indicating: 'A' = alive and <health_chars> One char for each device, indicating:
in-sync, 'a' = alive but not in-sync, 'D' = dead/failed.
- 'A' = alive and in-sync
- 'a' = alive but not in-sync
- 'D' = dead/failed.
<sync_ratio> The ratio indicating how much of the array has undergone <sync_ratio> The ratio indicating how much of the array has undergone
the process described by 'sync_action'. If the the process described by 'sync_action'. If the
'sync_action' is "check" or "repair", then the process 'sync_action' is "check" or "repair", then the process
of "resync" or "recover" can be considered complete. of "resync" or "recover" can be considered complete.
<sync_action> One of the following possible states: <sync_action> One of the following possible states:
idle - No synchronization action is being performed.
frozen - The current action has been halted. idle
resync - Array is undergoing its initial synchronization - No synchronization action is being performed.
frozen
- The current action has been halted.
resync
- Array is undergoing its initial synchronization
or is resynchronizing after an unclean shutdown or is resynchronizing after an unclean shutdown
(possibly aided by a bitmap). (possibly aided by a bitmap).
recover - A device in the array is being rebuilt or recover
- A device in the array is being rebuilt or
replaced. replaced.
check - A user-initiated full check of the array is check
- A user-initiated full check of the array is
being performed. All blocks are read and being performed. All blocks are read and
checked for consistency. The number of checked for consistency. The number of
discrepancies found are recorded in discrepancies found are recorded in
<mismatch_cnt>. No changes are made to the <mismatch_cnt>. No changes are made to the
array by this action. array by this action.
repair - The same as "check", but discrepancies are repair
- The same as "check", but discrepancies are
corrected. corrected.
reshape - The array is undergoing a reshape. reshape
- The array is undergoing a reshape.
<mismatch_cnt> The number of discrepancies found between mirror copies <mismatch_cnt> The number of discrepancies found between mirror copies
in RAID1/10 or wrong parity values found in RAID4/5/6. in RAID1/10 or wrong parity values found in RAID4/5/6.
This value is valid only after a "check" of the array This value is valid only after a "check" of the array
@ -261,10 +318,11 @@ recovery. Here is a fuller description of the individual fields:
<data_offset> The current data offset to the start of the user data on <data_offset> The current data offset to the start of the user data on
each component device of a raid set (see the respective each component device of a raid set (see the respective
raid parameter to support out-of-place reshaping). raid parameter to support out-of-place reshaping).
<journal_char> 'A' - active write-through journal device. <journal_char> - 'A' - active write-through journal device.
'a' - active write-back journal device. - 'a' - active write-back journal device.
'D' - dead journal device. - 'D' - dead journal device.
'-' - no journal device. - '-' - no journal device.
=============== =========================================================
Message Interface Message Interface
@ -272,12 +330,15 @@ Message Interface
The dm-raid target will accept certain actions through the 'message' interface. The dm-raid target will accept certain actions through the 'message' interface.
('man dmsetup' for more information on the message interface.) These actions ('man dmsetup' for more information on the message interface.) These actions
include: include:
"idle" - Halt the current sync action.
"frozen" - Freeze the current sync action. ========= ================================================
"resync" - Initiate/continue a resync. "idle" Halt the current sync action.
"recover"- Initiate/continue a recover process. "frozen" Freeze the current sync action.
"check" - Initiate a check (i.e. a "scrub") of the array. "resync" Initiate/continue a resync.
"repair" - Initiate a repair of the array. "recover" Initiate/continue a recover process.
"check" Initiate a check (i.e. a "scrub") of the array.
"repair" Initiate a repair of the array.
========= ================================================
Discard Support Discard Support
@ -307,48 +368,52 @@ increasingly whitelisted in the kernel and can thus be trusted.
For trusted devices, the following dm-raid module parameter can be set For trusted devices, the following dm-raid module parameter can be set
to safely enable discard support for RAID 4/5/6: to safely enable discard support for RAID 4/5/6:
'devices_handle_discards_safely' 'devices_handle_discards_safely'
Version History Version History
--------------- ---------------
1.0.0 Initial version. Support for RAID 4/5/6
1.1.0 Added support for RAID 1 ::
1.2.0 Handle creation of arrays that contain failed devices.
1.3.0 Added support for RAID 10 1.0.0 Initial version. Support for RAID 4/5/6
1.3.1 Allow device replacement/rebuild for RAID 10 1.1.0 Added support for RAID 1
1.3.2 Fix/improve redundancy checking for RAID10 1.2.0 Handle creation of arrays that contain failed devices.
1.4.0 Non-functional change. Removes arg from mapping function. 1.3.0 Added support for RAID 10
1.4.1 RAID10 fix redundancy validation checks (commit 55ebbb5). 1.3.1 Allow device replacement/rebuild for RAID 10
1.4.2 Add RAID10 "far" and "offset" algorithm support. 1.3.2 Fix/improve redundancy checking for RAID10
1.5.0 Add message interface to allow manipulation of the sync_action. 1.4.0 Non-functional change. Removes arg from mapping function.
1.4.1 RAID10 fix redundancy validation checks (commit 55ebbb5).
1.4.2 Add RAID10 "far" and "offset" algorithm support.
1.5.0 Add message interface to allow manipulation of the sync_action.
New status (STATUSTYPE_INFO) fields: sync_action and mismatch_cnt. New status (STATUSTYPE_INFO) fields: sync_action and mismatch_cnt.
1.5.1 Add ability to restore transiently failed devices on resume. 1.5.1 Add ability to restore transiently failed devices on resume.
1.5.2 'mismatch_cnt' is zero unless [last_]sync_action is "check". 1.5.2 'mismatch_cnt' is zero unless [last_]sync_action is "check".
1.6.0 Add discard support (and devices_handle_discard_safely module param). 1.6.0 Add discard support (and devices_handle_discard_safely module param).
1.7.0 Add support for MD RAID0 mappings. 1.7.0 Add support for MD RAID0 mappings.
1.8.0 Explicitly check for compatible flags in the superblock metadata 1.8.0 Explicitly check for compatible flags in the superblock metadata
and reject to start the raid set if any are set by a newer and reject to start the raid set if any are set by a newer
target version, thus avoiding data corruption on a raid set target version, thus avoiding data corruption on a raid set
with a reshape in progress. with a reshape in progress.
1.9.0 Add support for RAID level takeover/reshape/region size 1.9.0 Add support for RAID level takeover/reshape/region size
and set size reduction. and set size reduction.
1.9.1 Fix activation of existing RAID 4/10 mapped devices 1.9.1 Fix activation of existing RAID 4/10 mapped devices
1.9.2 Don't emit '- -' on the status table line in case the constructor 1.9.2 Don't emit '- -' on the status table line in case the constructor
fails reading a superblock. Correctly emit 'maj:min1 maj:min2' and fails reading a superblock. Correctly emit 'maj:min1 maj:min2' and
'D' on the status line. If '- -' is passed into the constructor, emit 'D' on the status line. If '- -' is passed into the constructor, emit
'- -' on the table line and '-' as the status line health character. '- -' on the table line and '-' as the status line health character.
1.10.0 Add support for raid4/5/6 journal device 1.10.0 Add support for raid4/5/6 journal device
1.10.1 Fix data corruption on reshape request 1.10.1 Fix data corruption on reshape request
1.11.0 Fix table line argument order 1.11.0 Fix table line argument order
(wrong raid10_copies/raid10_format sequence) (wrong raid10_copies/raid10_format sequence)
1.11.1 Add raid4/5/6 journal write-back support via journal_mode option 1.11.1 Add raid4/5/6 journal write-back support via journal_mode option
1.12.1 Fix for MD deadlock between mddev_suspend() and md_write_start() available 1.12.1 Fix for MD deadlock between mddev_suspend() and md_write_start() available
1.13.0 Fix dev_health status at end of "recover" (was 'a', now 'A') 1.13.0 Fix dev_health status at end of "recover" (was 'a', now 'A')
1.13.1 Fix deadlock caused by early md_stop_writes(). Also fix size an 1.13.1 Fix deadlock caused by early md_stop_writes(). Also fix size an
state races. state races.
1.13.2 Fix raid redundancy validation and avoid keeping raid set frozen 1.13.2 Fix raid redundancy validation and avoid keeping raid set frozen
1.14.0 Fix reshape race on small devices. Fix stripe adding reshape 1.14.0 Fix reshape race on small devices. Fix stripe adding reshape
deadlock/potential data corruption. Update superblock when deadlock/potential data corruption. Update superblock when
specific devices are requested via rebuild. Fix RAID leg specific devices are requested via rebuild. Fix RAID leg
rebuild errors. rebuild errors.

68
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@ -1,3 +1,4 @@
===============
dm-service-time dm-service-time
=============== ===============
@ -12,25 +13,34 @@ in a path-group, and it can be specified as a table argument.
The path selector name is 'service-time'. The path selector name is 'service-time'.
Table parameters for each path: [<repeat_count> [<relative_throughput>]] Table parameters for each path:
<repeat_count>: The number of I/Os to dispatch using the selected
[<repeat_count> [<relative_throughput>]]
<repeat_count>:
The number of I/Os to dispatch using the selected
path before switching to the next path. path before switching to the next path.
If not given, internal default is used. To check If not given, internal default is used. To check
the default value, see the activated table. the default value, see the activated table.
<relative_throughput>: The relative throughput value of the path <relative_throughput>:
The relative throughput value of the path
among all paths in the path-group. among all paths in the path-group.
The valid range is 0-100. The valid range is 0-100.
If not given, minimum value '1' is used. If not given, minimum value '1' is used.
If '0' is given, the path isn't selected while If '0' is given, the path isn't selected while
other paths having a positive value are available. other paths having a positive value are available.
Status for each path: <status> <fail-count> <in-flight-size> \ Status for each path:
<relative_throughput>
<status>: 'A' if the path is active, 'F' if the path is failed. <status> <fail-count> <in-flight-size> <relative_throughput>
<fail-count>: The number of path failures. <status>:
<in-flight-size>: The size of in-flight I/Os on the path. 'A' if the path is active, 'F' if the path is failed.
<relative_throughput>: The relative throughput value of the path <fail-count>:
among all paths in the path-group. The number of path failures.
<in-flight-size>:
The size of in-flight I/Os on the path.
<relative_throughput>:
The relative throughput value of the path
among all paths in the path-group.
Algorithm Algorithm
@ -39,7 +49,7 @@ Algorithm
dm-service-time adds the I/O size to 'in-flight-size' when the I/O is dm-service-time adds the I/O size to 'in-flight-size' when the I/O is
dispatched and subtracts when completed. dispatched and subtracts when completed.
Basically, dm-service-time selects a path having minimum service time Basically, dm-service-time selects a path having minimum service time
which is calculated by: which is calculated by::
('in-flight-size' + 'size-of-incoming-io') / 'relative_throughput' ('in-flight-size' + 'size-of-incoming-io') / 'relative_throughput'
@ -67,25 +77,25 @@ Examples
======== ========
In case that 2 paths (sda and sdb) are used with repeat_count == 128 In case that 2 paths (sda and sdb) are used with repeat_count == 128
and sda has an average throughput 1GB/s and sdb has 4GB/s, and sda has an average throughput 1GB/s and sdb has 4GB/s,
'relative_throughput' value may be '1' for sda and '4' for sdb. 'relative_throughput' value may be '1' for sda and '4' for sdb::
# echo "0 10 multipath 0 0 1 1 service-time 0 2 2 8:0 128 1 8:16 128 4" \ # echo "0 10 multipath 0 0 1 1 service-time 0 2 2 8:0 128 1 8:16 128 4" \
dmsetup create test dmsetup create test
# #
# dmsetup table # dmsetup table
test: 0 10 multipath 0 0 1 1 service-time 0 2 2 8:0 128 1 8:16 128 4 test: 0 10 multipath 0 0 1 1 service-time 0 2 2 8:0 128 1 8:16 128 4
# #
# dmsetup status # dmsetup status
test: 0 10 multipath 2 0 0 0 1 1 E 0 2 2 8:0 A 0 0 1 8:16 A 0 0 4 test: 0 10 multipath 2 0 0 0 1 1 E 0 2 2 8:0 A 0 0 1 8:16 A 0 0 4
Or '2' for sda and '8' for sdb would be also true. Or '2' for sda and '8' for sdb would be also true::
# echo "0 10 multipath 0 0 1 1 service-time 0 2 2 8:0 128 2 8:16 128 8" \ # echo "0 10 multipath 0 0 1 1 service-time 0 2 2 8:0 128 2 8:16 128 8" \
dmsetup create test dmsetup create test
# #
# dmsetup table # dmsetup table
test: 0 10 multipath 0 0 1 1 service-time 0 2 2 8:0 128 2 8:16 128 8 test: 0 10 multipath 0 0 1 1 service-time 0 2 2 8:0 128 2 8:16 128 8
# #
# dmsetup status # dmsetup status
test: 0 10 multipath 2 0 0 0 1 1 E 0 2 2 8:0 A 0 0 2 8:16 A 0 0 8 test: 0 10 multipath 2 0 0 0 1 1 E 0 2 2 8:0 A 0 0 2 8:16 A 0 0 8

110
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@ -0,0 +1,110 @@
====================
device-mapper uevent
====================
The device-mapper uevent code adds the capability to device-mapper to create
and send kobject uevents (uevents). Previously device-mapper events were only
available through the ioctl interface. The advantage of the uevents interface
is the event contains environment attributes providing increased context for
the event avoiding the need to query the state of the device-mapper device after
the event is received.
There are two functions currently for device-mapper events. The first function
listed creates the event and the second function sends the event(s)::
void dm_path_uevent(enum dm_uevent_type event_type, struct dm_target *ti,
const char *path, unsigned nr_valid_paths)
void dm_send_uevents(struct list_head *events, struct kobject *kobj)
The variables added to the uevent environment are:
Variable Name: DM_TARGET
------------------------
:Uevent Action(s): KOBJ_CHANGE
:Type: string
:Description:
:Value: Name of device-mapper target that generated the event.
Variable Name: DM_ACTION
------------------------
:Uevent Action(s): KOBJ_CHANGE
:Type: string
:Description:
:Value: Device-mapper specific action that caused the uevent action.
PATH_FAILED - A path has failed;
PATH_REINSTATED - A path has been reinstated.
Variable Name: DM_SEQNUM
------------------------
:Uevent Action(s): KOBJ_CHANGE
:Type: unsigned integer
:Description: A sequence number for this specific device-mapper device.
:Value: Valid unsigned integer range.
Variable Name: DM_PATH
----------------------
:Uevent Action(s): KOBJ_CHANGE
:Type: string
:Description: Major and minor number of the path device pertaining to this
event.
:Value: Path name in the form of "Major:Minor"
Variable Name: DM_NR_VALID_PATHS
--------------------------------
:Uevent Action(s): KOBJ_CHANGE
:Type: unsigned integer
:Description:
:Value: Valid unsigned integer range.
Variable Name: DM_NAME
----------------------
:Uevent Action(s): KOBJ_CHANGE
:Type: string
:Description: Name of the device-mapper device.
:Value: Name
Variable Name: DM_UUID
----------------------
:Uevent Action(s): KOBJ_CHANGE
:Type: string
:Description: UUID of the device-mapper device.
:Value: UUID. (Empty string if there isn't one.)
An example of the uevents generated as captured by udevmonitor is shown
below
1.) Path failure::
UEVENT[1192521009.711215] change@/block/dm-3
ACTION=change
DEVPATH=/block/dm-3
SUBSYSTEM=block
DM_TARGET=multipath
DM_ACTION=PATH_FAILED
DM_SEQNUM=1
DM_PATH=8:32
DM_NR_VALID_PATHS=0
DM_NAME=mpath2
DM_UUID=mpath-35333333000002328
MINOR=3
MAJOR=253
SEQNUM=1130
2.) Path reinstate::
UEVENT[1192521132.989927] change@/block/dm-3
ACTION=change
DEVPATH=/block/dm-3
SUBSYSTEM=block
DM_TARGET=multipath
DM_ACTION=PATH_REINSTATED
DM_SEQNUM=2
DM_PATH=8:32
DM_NR_VALID_PATHS=1
DM_NAME=mpath2
DM_UUID=mpath-35333333000002328
MINOR=3
MAJOR=253
SEQNUM=1131

97
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@ -1,97 +0,0 @@
The device-mapper uevent code adds the capability to device-mapper to create
and send kobject uevents (uevents). Previously device-mapper events were only
available through the ioctl interface. The advantage of the uevents interface
is the event contains environment attributes providing increased context for
the event avoiding the need to query the state of the device-mapper device after
the event is received.
There are two functions currently for device-mapper events. The first function
listed creates the event and the second function sends the event(s).
void dm_path_uevent(enum dm_uevent_type event_type, struct dm_target *ti,
const char *path, unsigned nr_valid_paths)
void dm_send_uevents(struct list_head *events, struct kobject *kobj)
The variables added to the uevent environment are:
Variable Name: DM_TARGET
Uevent Action(s): KOBJ_CHANGE
Type: string
Description:
Value: Name of device-mapper target that generated the event.
Variable Name: DM_ACTION
Uevent Action(s): KOBJ_CHANGE
Type: string
Description:
Value: Device-mapper specific action that caused the uevent action.
PATH_FAILED - A path has failed.
PATH_REINSTATED - A path has been reinstated.
Variable Name: DM_SEQNUM
Uevent Action(s): KOBJ_CHANGE
Type: unsigned integer
Description: A sequence number for this specific device-mapper device.
Value: Valid unsigned integer range.
Variable Name: DM_PATH
Uevent Action(s): KOBJ_CHANGE
Type: string
Description: Major and minor number of the path device pertaining to this
event.
Value: Path name in the form of "Major:Minor"
Variable Name: DM_NR_VALID_PATHS
Uevent Action(s): KOBJ_CHANGE
Type: unsigned integer
Description:
Value: Valid unsigned integer range.
Variable Name: DM_NAME
Uevent Action(s): KOBJ_CHANGE
Type: string
Description: Name of the device-mapper device.
Value: Name
Variable Name: DM_UUID
Uevent Action(s): KOBJ_CHANGE
Type: string
Description: UUID of the device-mapper device.
Value: UUID. (Empty string if there isn't one.)
An example of the uevents generated as captured by udevmonitor is shown
below.
1.) Path failure.
UEVENT[1192521009.711215] change@/block/dm-3
ACTION=change
DEVPATH=/block/dm-3
SUBSYSTEM=block
DM_TARGET=multipath
DM_ACTION=PATH_FAILED
DM_SEQNUM=1
DM_PATH=8:32
DM_NR_VALID_PATHS=0
DM_NAME=mpath2
DM_UUID=mpath-35333333000002328
MINOR=3
MAJOR=253
SEQNUM=1130
2.) Path reinstate.
UEVENT[1192521132.989927] change@/block/dm-3
ACTION=change
DEVPATH=/block/dm-3
SUBSYSTEM=block
DM_TARGET=multipath
DM_ACTION=PATH_REINSTATED
DM_SEQNUM=2
DM_PATH=8:32
DM_NR_VALID_PATHS=1
DM_NAME=mpath2
DM_UUID=mpath-35333333000002328
MINOR=3
MAJOR=253
SEQNUM=1131

10
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@ -1,3 +1,4 @@
========
dm-zoned dm-zoned
======== ========
@ -133,12 +134,13 @@ A zoned block device must first be formatted using the dmzadm tool. This
will analyze the device zone configuration, determine where to place the will analyze the device zone configuration, determine where to place the
metadata sets on the device and initialize the metadata sets. metadata sets on the device and initialize the metadata sets.
Ex: Ex::
dmzadm --format /dev/sdxx dmzadm --format /dev/sdxx
For a formatted device, the target can be created normally with the For a formatted device, the target can be created normally with the
dmsetup utility. The only parameter that dm-zoned requires is the dmsetup utility. The only parameter that dm-zoned requires is the
underlying zoned block device name. Ex: underlying zoned block device name. Ex::
echo "0 `blockdev --getsize ${dev}` zoned ${dev}" | dmsetup create dmz-`basename ${dev}` echo "0 `blockdev --getsize ${dev}` zoned ${dev}" | \
dmsetup create dmz-`basename ${dev}`

36
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@ -1,3 +1,7 @@
======
dm-era
======
Introduction Introduction
============ ============
@ -14,12 +18,14 @@ coherency after rolling back a vendor snapshot.
Constructor Constructor
=========== ===========
era <metadata dev> <origin dev> <block size> era <metadata dev> <origin dev> <block size>
metadata dev : fast device holding the persistent metadata ================ ======================================================
origin dev : device holding data blocks that may change metadata dev fast device holding the persistent metadata
block size : block size of origin data device, granularity that is origin dev device holding data blocks that may change
tracked by the target block size block size of origin data device, granularity that is
tracked by the target
================ ======================================================
Messages Messages
======== ========
@ -49,14 +55,16 @@ Status
<metadata block size> <#used metadata blocks>/<#total metadata blocks> <metadata block size> <#used metadata blocks>/<#total metadata blocks>
<current era> <held metadata root | '-'> <current era> <held metadata root | '-'>
metadata block size : Fixed block size for each metadata block in ========================= ==============================================
sectors metadata block size Fixed block size for each metadata block in
#used metadata blocks : Number of metadata blocks used sectors
#total metadata blocks : Total number of metadata blocks #used metadata blocks Number of metadata blocks used
current era : The current era #total metadata blocks Total number of metadata blocks
held metadata root : The location, in blocks, of the metadata root current era The current era
that has been 'held' for userspace read held metadata root The location, in blocks, of the metadata root
access. '-' indicates there is no held root that has been 'held' for userspace read
access. '-' indicates there is no held root
========================= ==============================================
Detailed use case Detailed use case
================= =================
@ -88,7 +96,7 @@ Memory usage
The target uses a bitset to record writes in the current era. It also The target uses a bitset to record writes in the current era. It also
has a spare bitset ready for switching over to a new era. Other than has a spare bitset ready for switching over to a new era. Other than
that it uses a few 4k blocks for updating metadata. that it uses a few 4k blocks for updating metadata::
(4 * nr_blocks) bytes + buffers (4 * nr_blocks) bytes + buffers

44
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@ -0,0 +1,44 @@
:orphan:
=============
Device Mapper
=============
.. toctree::
:maxdepth: 1
cache-policies
cache
delay
dm-crypt
dm-flakey
dm-init
dm-integrity
dm-io
dm-log
dm-queue-length
dm-raid
dm-service-time
dm-uevent
dm-zoned
era
kcopyd
linear
log-writes
persistent-data
snapshot
statistics
striped
switch
thin-provisioning
unstriped
verity
writecache
zero
.. only:: subproject and html
Indices
=======
* :ref:`genindex`

10
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@ -1,3 +1,4 @@
======
kcopyd kcopyd
====== ======
@ -7,7 +8,7 @@ notification. It is used by dm-snapshot and dm-mirror.
Users of kcopyd must first create a client and indicate how many memory pages Users of kcopyd must first create a client and indicate how many memory pages
to set aside for their copy jobs. This is done with a call to to set aside for their copy jobs. This is done with a call to
kcopyd_client_create(). kcopyd_client_create()::
int kcopyd_client_create(unsigned int num_pages, int kcopyd_client_create(unsigned int num_pages,
struct kcopyd_client **result); struct kcopyd_client **result);
@ -16,7 +17,7 @@ To start a copy job, the user must set up io_region structures to describe
the source and destinations of the copy. Each io_region indicates a the source and destinations of the copy. Each io_region indicates a
block-device along with the starting sector and size of the region. The source block-device along with the starting sector and size of the region. The source
of the copy is given as one io_region structure, and the destinations of the of the copy is given as one io_region structure, and the destinations of the
copy are given as an array of io_region structures. copy are given as an array of io_region structures::
struct io_region { struct io_region {
struct block_device *bdev; struct block_device *bdev;
@ -26,7 +27,7 @@ copy are given as an array of io_region structures.
To start the copy, the user calls kcopyd_copy(), passing in the client To start the copy, the user calls kcopyd_copy(), passing in the client
pointer, pointers to the source and destination io_regions, the name of a pointer, pointers to the source and destination io_regions, the name of a
completion callback routine, and a pointer to some context data for the copy. completion callback routine, and a pointer to some context data for the copy::
int kcopyd_copy(struct kcopyd_client *kc, struct io_region *from, int kcopyd_copy(struct kcopyd_client *kc, struct io_region *from,
unsigned int num_dests, struct io_region *dests, unsigned int num_dests, struct io_region *dests,
@ -41,7 +42,6 @@ write error occurred during the copy.
When a user is done with all their copy jobs, they should call When a user is done with all their copy jobs, they should call
kcopyd_client_destroy() to delete the kcopyd client, which will release the kcopyd_client_destroy() to delete the kcopyd client, which will release the
associated memory pages. associated memory pages::
void kcopyd_client_destroy(struct kcopyd_client *kc); void kcopyd_client_destroy(struct kcopyd_client *kc);

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@ -0,0 +1,63 @@
=========
dm-linear
=========
Device-Mapper's "linear" target maps a linear range of the Device-Mapper
device onto a linear range of another device. This is the basic building
block of logical volume managers.
Parameters: <dev path> <offset>
<dev path>:
Full pathname to the underlying block-device, or a
"major:minor" device-number.
<offset>:
Starting sector within the device.
Example scripts
===============
::
#!/bin/sh
# Create an identity mapping for a device
echo "0 `blockdev --getsz $1` linear $1 0" | dmsetup create identity
::
#!/bin/sh
# Join 2 devices together
size1=`blockdev --getsz $1`
size2=`blockdev --getsz $2`
echo "0 $size1 linear $1 0
$size1 $size2 linear $2 0" | dmsetup create joined
::
#!/usr/bin/perl -w
# Split a device into 4M chunks and then join them together in reverse order.
my $name = "reverse";
my $extent_size = 4 * 1024 * 2;
my $dev = $ARGV[0];
my $table = "";
my $count = 0;
if (!defined($dev)) {
die("Please specify a device.\n");
}
my $dev_size = `blockdev --getsz $dev`;
my $extents = int($dev_size / $extent_size) -
(($dev_size % $extent_size) ? 1 : 0);
while ($extents > 0) {
my $this_start = $count * $extent_size;
$extents--;
$count++;
my $this_offset = $extents * $extent_size;
$table .= "$this_start $extent_size linear $dev $this_offset\n";
}
`echo \"$table\" | dmsetup create $name`;

61
Documentation/device-mapper/linear.txt
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@ -1,61 +0,0 @@
dm-linear
=========
Device-Mapper's "linear" target maps a linear range of the Device-Mapper
device onto a linear range of another device. This is the basic building
block of logical volume managers.
Parameters: <dev path> <offset>
<dev path>: Full pathname to the underlying block-device, or a
"major:minor" device-number.
<offset>: Starting sector within the device.
Example scripts
===============
[[
#!/bin/sh
# Create an identity mapping for a device
echo "0 `blockdev --getsz $1` linear $1 0" | dmsetup create identity
]]
[[
#!/bin/sh
# Join 2 devices together
size1=`blockdev --getsz $1`
size2=`blockdev --getsz $2`
echo "0 $size1 linear $1 0
$size1 $size2 linear $2 0" | dmsetup create joined
]]
[[
#!/usr/bin/perl -w
# Split a device into 4M chunks and then join them together in reverse order.
my $name = "reverse";
my $extent_size = 4 * 1024 * 2;
my $dev = $ARGV[0];
my $table = "";
my $count = 0;
if (!defined($dev)) {
die("Please specify a device.\n");
}
my $dev_size = `blockdev --getsz $dev`;
my $extents = int($dev_size / $extent_size) -
(($dev_size % $extent_size) ? 1 : 0);
while ($extents > 0) {
my $this_start = $count * $extent_size;
$extents--;
$count++;
my $this_offset = $extents * $extent_size;
$table .= "$this_start $extent_size linear $dev $this_offset\n";
}
`echo \"$table\" | dmsetup create $name`;
]]

91
Documentation/device-mapper/log-writes.txt → Documentation/device-mapper/log-writes.rst
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@ -1,3 +1,4 @@
=============
dm-log-writes dm-log-writes
============= =============
@ -25,11 +26,11 @@ completed WRITEs, at the time the REQ_PREFLUSH is issued, are added in order to
simulate the worst case scenario with regard to power failures. Consider the simulate the worst case scenario with regard to power failures. Consider the
following example (W means write, C means complete): following example (W means write, C means complete):
W1,W2,W3,C3,C2,Wflush,C1,Cflush W1,W2,W3,C3,C2,Wflush,C1,Cflush
The log would show the following The log would show the following:
W3,W2,flush,W1.... W3,W2,flush,W1....
Again this is to simulate what is actually on disk, this allows us to detect Again this is to simulate what is actually on disk, this allows us to detect
cases where a power failure at a particular point in time would create an cases where a power failure at a particular point in time would create an
@ -42,11 +43,11 @@ Any REQ_OP_DISCARD requests are treated like WRITE requests. Otherwise we would
have all the DISCARD requests, and then the WRITE requests and then the FLUSH have all the DISCARD requests, and then the WRITE requests and then the FLUSH
request. Consider the following example: request. Consider the following example:
WRITE block 1, DISCARD block 1, FLUSH WRITE block 1, DISCARD block 1, FLUSH
If we logged DISCARD when it completed, the replay would look like this If we logged DISCARD when it completed, the replay would look like this:
DISCARD 1, WRITE 1, FLUSH DISCARD 1, WRITE 1, FLUSH
which isn't quite what happened and wouldn't be caught during the log replay. which isn't quite what happened and wouldn't be caught during the log replay.
@ -57,15 +58,19 @@ i) Constructor
log-writes <dev_path> <log_dev_path> log-writes <dev_path> <log_dev_path>
dev_path : Device that all of the IO will go to normally. ============= ==============================================
log_dev_path : Device where the log entries are written to. dev_path Device that all of the IO will go to normally.
log_dev_path Device where the log entries are written to.
============= ==============================================
ii) Status ii) Status
<#logged entries> <highest allocated sector> <#logged entries> <highest allocated sector>
#logged entries : Number of logged entries =========================== ========================
highest allocated sector : Highest allocated sector #logged entries Number of logged entries
highest allocated sector Highest allocated sector
=========================== ========================
iii) Messages iii) Messages
@ -75,15 +80,15 @@ iii) Messages
For example say you want to fsck a file system after every For example say you want to fsck a file system after every
write, but first you need to replay up to the mkfs to make sure write, but first you need to replay up to the mkfs to make sure
we're fsck'ing something reasonable, you would do something like we're fsck'ing something reasonable, you would do something like
this: this::
mkfs.btrfs -f /dev/mapper/log mkfs.btrfs -f /dev/mapper/log
dmsetup message log 0 mark mkfs dmsetup message log 0 mark mkfs
<run test> <run test>
This would allow you to replay the log up to the mkfs mark and This would allow you to replay the log up to the mkfs mark and
then replay from that point on doing the fsck check in the then replay from that point on doing the fsck check in the
interval that you want. interval that you want.
Every log has a mark at the end labeled "dm-log-writes-end". Every log has a mark at the end labeled "dm-log-writes-end".
@ -97,42 +102,42 @@ Example usage
============= =============
Say you want to test fsync on your file system. You would do something like Say you want to test fsync on your file system. You would do something like
this: this::
TABLE="0 $(blockdev --getsz /dev/sdb) log-writes /dev/sdb /dev/sdc" TABLE="0 $(blockdev --getsz /dev/sdb) log-writes /dev/sdb /dev/sdc"
dmsetup create log --table "$TABLE" dmsetup create log --table "$TABLE"
mkfs.btrfs -f /dev/mapper/log mkfs.btrfs -f /dev/mapper/log
dmsetup message log 0 mark mkfs dmsetup message log 0 mark mkfs
mount /dev/mapper/log /mnt/btrfs-test mount /dev/mapper/log /mnt/btrfs-test
<some test that does fsync at the end> <some test that does fsync at the end>
dmsetup message log 0 mark fsync dmsetup message log 0 mark fsync
md5sum /mnt/btrfs-test/foo md5sum /mnt/btrfs-test/foo
umount /mnt/btrfs-test umount /mnt/btrfs-test
dmsetup remove log dmsetup remove log
replay-log --log /dev/sdc --replay /dev/sdb --end-mark fsync replay-log --log /dev/sdc --replay /dev/sdb --end-mark fsync
mount /dev/sdb /mnt/btrfs-test mount /dev/sdb /mnt/btrfs-test
md5sum /mnt/btrfs-test/foo md5sum /mnt/btrfs-test/foo
<verify md5sum's are correct> <verify md5sum's are correct>
Another option is to do a complicated file system operation and verify the file Another option is to do a complicated file system operation and verify the file
system is consistent during the entire operation. You could do this with: system is consistent during the entire operation. You could do this with:
TABLE="0 $(blockdev --getsz /dev/sdb) log-writes /dev/sdb /dev/sdc" TABLE="0 $(blockdev --getsz /dev/sdb) log-writes /dev/sdb /dev/sdc"
dmsetup create log --table "$TABLE" dmsetup create log --table "$TABLE"
mkfs.btrfs -f /dev/mapper/log mkfs.btrfs -f /dev/mapper/log
dmsetup message log 0 mark mkfs dmsetup message log 0 mark mkfs
mount /dev/mapper/log /mnt/btrfs-test mount /dev/mapper/log /mnt/btrfs-test
<fsstress to dirty the fs> <fsstress to dirty the fs>
btrfs filesystem balance /mnt/btrfs-test btrfs filesystem balance /mnt/btrfs-test
umount /mnt/btrfs-test umount /mnt/btrfs-test
dmsetup remove log dmsetup remove log
replay-log --log /dev/sdc --replay /dev/sdb --end-mark mkfs replay-log --log /dev/sdc --replay /dev/sdb --end-mark mkfs
btrfsck /dev/sdb btrfsck /dev/sdb
replay-log --log /dev/sdc --replay /dev/sdb --start-mark mkfs \ replay-log --log /dev/sdc --replay /dev/sdb --start-mark mkfs \
--fsck "btrfsck /dev/sdb" --check fua --fsck "btrfsck /dev/sdb" --check fua
And that will replay the log until it sees a FUA request, run the fsck command And that will replay the log until it sees a FUA request, run the fsck command

4
Documentation/device-mapper/persistent-data.txt → Documentation/device-mapper/persistent-data.rst
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@ -1,3 +1,7 @@
===============
Persistent data
===============
Introduction Introduction
============ ============

116
Documentation/device-mapper/snapshot.txt → Documentation/device-mapper/snapshot.rst
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@ -1,15 +1,16 @@
==============================
Device-mapper snapshot support Device-mapper snapshot support
============================== ==============================
Device-mapper allows you, without massive data copying: Device-mapper allows you, without massive data copying:
*) To create snapshots of any block device i.e. mountable, saved states of - To create snapshots of any block device i.e. mountable, saved states of
the block device which are also writable without interfering with the the block device which are also writable without interfering with the
original content; original content;
*) To create device "forks", i.e. multiple different versions of the - To create device "forks", i.e. multiple different versions of the
same data stream. same data stream.
*) To merge a snapshot of a block device back into the snapshot's origin - To merge a snapshot of a block device back into the snapshot's origin
device. device.
In the first two cases, dm copies only the chunks of data that get In the first two cases, dm copies only the chunks of data that get
changed and uses a separate copy-on-write (COW) block device for changed and uses a separate copy-on-write (COW) block device for
@ -22,7 +23,7 @@ the origin device.
There are three dm targets available: There are three dm targets available:
snapshot, snapshot-origin, and snapshot-merge. snapshot, snapshot-origin, and snapshot-merge.
*) snapshot-origin <origin> - snapshot-origin <origin>
which will normally have one or more snapshots based on it. which will normally have one or more snapshots based on it.
Reads will be mapped directly to the backing device. For each write, the Reads will be mapped directly to the backing device. For each write, the
@ -30,7 +31,7 @@ original data will be saved in the <COW device> of each snapshot to keep
its visible content unchanged, at least until the <COW device> fills up. its visible content unchanged, at least until the <COW device> fills up.
*) snapshot <origin> <COW device> <persistent?> <chunksize> - snapshot <origin> <COW device> <persistent?> <chunksize>
A snapshot of the <origin> block device is created. Changed chunks of A snapshot of the <origin> block device is created. Changed chunks of
<chunksize> sectors will be stored on the <COW device>. Writes will <chunksize> sectors will be stored on the <COW device>. Writes will
@ -83,25 +84,25 @@ When you create the first LVM2 snapshot of a volume, four dm devices are used:
source volume), whose table is replaced by a "snapshot-origin" mapping source volume), whose table is replaced by a "snapshot-origin" mapping
from device #1. from device #1.
A fixed naming scheme is used, so with the following commands: A fixed naming scheme is used, so with the following commands::
lvcreate -L 1G -n base volumeGroup lvcreate -L 1G -n base volumeGroup
lvcreate -L 100M --snapshot -n snap volumeGroup/base lvcreate -L 100M --snapshot -n snap volumeGroup/base
we'll have this situation (with volumes in above order): we'll have this situation (with volumes in above order)::
# dmsetup table|grep volumeGroup # dmsetup table|grep volumeGroup
volumeGroup-base-real: 0 2097152 linear 8:19 384 volumeGroup-base-real: 0 2097152 linear 8:19 384
volumeGroup-snap-cow: 0 204800 linear 8:19 2097536 volumeGroup-snap-cow: 0 204800 linear 8:19 2097536
volumeGroup-snap: 0 2097152 snapshot 254:11 254:12 P 16 volumeGroup-snap: 0 2097152 snapshot 254:11 254:12 P 16
volumeGroup-base: 0 2097152 snapshot-origin 254:11 volumeGroup-base: 0 2097152 snapshot-origin 254:11
# ls -lL /dev/mapper/volumeGroup-* # ls -lL /dev/mapper/volumeGroup-*
brw------- 1 root root 254, 11 29 ago 18:15 /dev/mapper/volumeGroup-base-real brw------- 1 root root 254, 11 29 ago 18:15 /dev/mapper/volumeGroup-base-real
brw------- 1 root root 254, 12 29 ago 18:15 /dev/mapper/volumeGroup-snap-cow brw------- 1 root root 254, 12 29 ago 18:15 /dev/mapper/volumeGroup-snap-cow
brw------- 1 root root 254, 13 29 ago 18:15 /dev/mapper/volumeGroup-snap brw------- 1 root root 254, 13 29 ago 18:15 /dev/mapper/volumeGroup-snap
brw------- 1 root root 254, 10 29 ago 18:14 /dev/mapper/volumeGroup-base brw------- 1 root root 254, 10 29 ago 18:14 /dev/mapper/volumeGroup-base
How snapshot-merge is used by LVM2 How snapshot-merge is used by LVM2
@ -114,27 +115,28 @@ merging snapshot after it completes. The "snapshot" that hands over its
COW device to the "snapshot-merge" is deactivated (unless using lvchange COW device to the "snapshot-merge" is deactivated (unless using lvchange
--refresh); but if it is left active it will simply return I/O errors. --refresh); but if it is left active it will simply return I/O errors.
A snapshot will merge into its origin with the following command: A snapshot will merge into its origin with the following command::
lvconvert --merge volumeGroup/snap lvconvert --merge volumeGroup/snap
we'll now have this situation: we'll now have this situation::
# dmsetup table|grep volumeGroup # dmsetup table|grep volumeGroup
volumeGroup-base-real: 0 2097152 linear 8:19 384 volumeGroup-base-real: 0 2097152 linear 8:19 384
volumeGroup-base-cow: 0 204800 linear 8:19 2097536 volumeGroup-base-cow: 0 204800 linear 8:19 2097536
volumeGroup-base: 0 2097152 snapshot-merge 254:11 254:12 P 16 volumeGroup-base: 0 2097152 snapshot-merge 254:11 254:12 P 16
# ls -lL /dev/mapper/volumeGroup-* # ls -lL /dev/mapper/volumeGroup-*
brw------- 1 root root 254, 11 29 ago 18:15 /dev/mapper/volumeGroup-base-real brw------- 1 root root 254, 11 29 ago 18:15 /dev/mapper/volumeGroup-base-real
brw------- 1 root root 254, 12 29 ago 18:16 /dev/mapper/volumeGroup-base-cow brw------- 1 root root 254, 12 29 ago 18:16 /dev/mapper/volumeGroup-base-cow
brw------- 1 root root 254, 10 29 ago 18:16 /dev/mapper/volumeGroup-base brw------- 1 root root 254, 10 29 ago 18:16 /dev/mapper/volumeGroup-base
How to determine when a merging is complete How to determine when a merging is complete
=========================================== ===========================================
The snapshot-merge and snapshot status lines end with: The snapshot-merge and snapshot status lines end with:
<sectors_allocated>/<total_sectors> <metadata_sectors> <sectors_allocated>/<total_sectors> <metadata_sectors>
Both <sectors_allocated> and <total_sectors> include both data and metadata. Both <sectors_allocated> and <total_sectors> include both data and metadata.
@ -142,35 +144,37 @@ During merging, the number of sectors allocated gets smaller and
smaller. Merging has finished when the number of sectors holding data smaller. Merging has finished when the number of sectors holding data
is zero, in other words <sectors_allocated> == <metadata_sectors>. is zero, in other words <sectors_allocated> == <metadata_sectors>.
Here is a practical example (using a hybrid of lvm and dmsetup commands): Here is a practical example (using a hybrid of lvm and dmsetup commands)::
# lvs # lvs
LV VG Attr LSize Origin Snap% Move Log Copy% Convert LV VG Attr LSize Origin Snap% Move Log Copy% Convert
base volumeGroup owi-a- 4.00g base volumeGroup owi-a- 4.00g
snap volumeGroup swi-a- 1.00g base 18.97 snap volumeGroup swi-a- 1.00g base 18.97
# dmsetup status volumeGroup-snap # dmsetup status volumeGroup-snap
0 8388608 snapshot 397896/2097152 1560 0 8388608 snapshot 397896/2097152 1560
^^^^ metadata sectors ^^^^ metadata sectors
# lvconvert --merge -b volumeGroup/snap # lvconvert --merge -b volumeGroup/snap
Merging of volume snap started. Merging of volume snap started.
# lvs volumeGroup/snap # lvs volumeGroup/snap
LV VG Attr LSize Origin Snap% Move Log Copy% Convert LV VG Attr LSize Origin Snap% Move Log Copy% Convert
base volumeGroup Owi-a- 4.00g 17.23 base volumeGroup Owi-a- 4.00g 17.23
# dmsetup status volumeGroup-base # dmsetup status volumeGroup-base
0 8388608 snapshot-merge 281688/2097152 1104 0 8388608 snapshot-merge 281688/2097152 1104
# dmsetup status volumeGroup-base # dmsetup status volumeGroup-base
0 8388608 snapshot-merge 180480/2097152 712 0 8388608 snapshot-merge 180480/2097152 712
# dmsetup status volumeGroup-base # dmsetup status volumeGroup-base
0 8388608 snapshot-merge 16/2097152 16 0 8388608 snapshot-merge 16/2097152 16
Merging has finished. Merging has finished.
# lvs ::
LV VG Attr LSize Origin Snap% Move Log Copy% Convert
base volumeGroup owi-a- 4.00g # lvs
LV VG Attr LSize Origin Snap% Move Log Copy% Convert
base volumeGroup owi-a- 4.00g

62
Documentation/device-mapper/statistics.txt → Documentation/device-mapper/statistics.rst
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@ -1,3 +1,4 @@
=============
DM statistics DM statistics
============= =============
@ -11,7 +12,7 @@ Individual statistics will be collected for each step-sized area within
the range specified. the range specified.
The I/O statistics counters for each step-sized area of a region are The I/O statistics counters for each step-sized area of a region are
in the same format as /sys/block/*/stat or /proc/diskstats (see: in the same format as `/sys/block/*/stat` or `/proc/diskstats` (see:
Documentation/iostats.txt). But two extra counters (12 and 13) are Documentation/iostats.txt). But two extra counters (12 and 13) are
provided: total time spent reading and writing. When the histogram provided: total time spent reading and writing. When the histogram
argument is used, the 14th parameter is reported that represents the argument is used, the 14th parameter is reported that represents the
@ -32,40 +33,45 @@ on each other's data.
The creation of DM statistics will allocate memory via kmalloc or The creation of DM statistics will allocate memory via kmalloc or
fallback to using vmalloc space. At most, 1/4 of the overall system fallback to using vmalloc space. At most, 1/4 of the overall system
memory may be allocated by DM statistics. The admin can see how much memory may be allocated by DM statistics. The admin can see how much
memory is used by reading memory is used by reading:
/sys/module/dm_mod/parameters/stats_current_allocated_bytes
/sys/module/dm_mod/parameters/stats_current_allocated_bytes
Messages Messages
======== ========
@stats_create <range> <step> @stats_create <range> <step> [<number_of_optional_arguments> <optional_arguments>...] [<program_id> [<aux_data>]]
[<number_of_optional_arguments> <optional_arguments>...]
[<program_id> [<aux_data>]]
Create a new region and return the region_id. Create a new region and return the region_id.
<range> <range>
"-" - whole device "-"
"<start_sector>+<length>" - a range of <length> 512-byte sectors whole device
starting with <start_sector>. "<start_sector>+<length>"
a range of <length> 512-byte sectors
starting with <start_sector>.
<step> <step>
"<area_size>" - the range is subdivided into areas each containing "<area_size>"
<area_size> sectors. the range is subdivided into areas each containing
"/<number_of_areas>" - the range is subdivided into the specified <area_size> sectors.
number of areas. "/<number_of_areas>"
the range is subdivided into the specified
number of areas.
<number_of_optional_arguments> <number_of_optional_arguments>
The number of optional arguments The number of optional arguments
<optional_arguments> <optional_arguments>
The following optional arguments are supported The following optional arguments are supported:
precise_timestamps - use precise timer with nanosecond resolution
precise_timestamps
use precise timer with nanosecond resolution
instead of the "jiffies" variable. When this argument is instead of the "jiffies" variable. When this argument is
used, the resulting times are in nanoseconds instead of used, the resulting times are in nanoseconds instead of
milliseconds. Precise timestamps are a little bit slower milliseconds. Precise timestamps are a little bit slower
to obtain than jiffies-based timestamps. to obtain than jiffies-based timestamps.
histogram:n1,n2,n3,n4,... - collect histogram of latencies. The histogram:n1,n2,n3,n4,...
collect histogram of latencies. The
numbers n1, n2, etc are times that represent the boundaries numbers n1, n2, etc are times that represent the boundaries
of the histogram. If precise_timestamps is not used, the of the histogram. If precise_timestamps is not used, the
times are in milliseconds, otherwise they are in times are in milliseconds, otherwise they are in
@ -96,21 +102,18 @@ Messages
@stats_list message, but it doesn't use this value for anything. @stats_list message, but it doesn't use this value for anything.
@stats_delete <region_id> @stats_delete <region_id>
Delete the region with the specified id. Delete the region with the specified id.
<region_id> <region_id>
region_id returned from @stats_create region_id returned from @stats_create
@stats_clear <region_id> @stats_clear <region_id>
Clear all the counters except the in-flight i/o counters. Clear all the counters except the in-flight i/o counters.
<region_id> <region_id>
region_id returned from @stats_create region_id returned from @stats_create
@stats_list [<program_id>] @stats_list [<program_id>]
List all regions registered with @stats_create. List all regions registered with @stats_create.
<program_id> <program_id>
@ -127,7 +130,6 @@ Messages
if they were specified when creating the region. if they were specified when creating the region.
@stats_print <region_id> [<starting_line> <number_of_lines>] @stats_print <region_id> [<starting_line> <number_of_lines>]
Print counters for each step-sized area of a region. Print counters for each step-sized area of a region.
<region_id> <region_id>
@ -143,10 +145,11 @@ Messages
Output format for each step-sized area of a region: Output format for each step-sized area of a region:
<start_sector>+<length> counters <start_sector>+<length>
counters
The first 11 counters have the same meaning as The first 11 counters have the same meaning as
/sys/block/*/stat or /proc/diskstats. `/sys/block/*/stat or /proc/diskstats`.
Please refer to Documentation/iostats.txt for details. Please refer to Documentation/iostats.txt for details.
@ -163,11 +166,11 @@ Messages
11. the weighted number of milliseconds spent doing I/Os 11. the weighted number of milliseconds spent doing I/Os
Additional counters: Additional counters:
12. the total time spent reading in milliseconds 12. the total time spent reading in milliseconds
13. the total time spent writing in milliseconds 13. the total time spent writing in milliseconds
@stats_print_clear <region_id> [<starting_line> <number_of_lines>] @stats_print_clear <region_id> [<starting_line> <number_of_lines>]
Atomically print and then clear all the counters except the Atomically print and then clear all the counters except the
in-flight i/o counters. Useful when the client consuming the in-flight i/o counters. Useful when the client consuming the
statistics does not want to lose any statistics (those updated statistics does not want to lose any statistics (those updated
@ -185,7 +188,6 @@ Messages
If omitted, all lines are printed and then cleared. If omitted, all lines are printed and then cleared.
@stats_set_aux <region_id> <aux_data> @stats_set_aux <region_id> <aux_data>
Store auxiliary data aux_data for the specified region. Store auxiliary data aux_data for the specified region.
<region_id> <region_id>
@ -201,23 +203,23 @@ Examples
======== ========
Subdivide the DM device 'vol' into 100 pieces and start collecting Subdivide the DM device 'vol' into 100 pieces and start collecting
statistics on them: statistics on them::
dmsetup message vol 0 @stats_create - /100 dmsetup message vol 0 @stats_create - /100
Set the auxiliary data string to "foo bar baz" (the escape for each Set the auxiliary data string to "foo bar baz" (the escape for each
space must also be escaped, otherwise the shell will consume them): space must also be escaped, otherwise the shell will consume them)::
dmsetup message vol 0 @stats_set_aux 0 foo\\ bar\\ baz dmsetup message vol 0 @stats_set_aux 0 foo\\ bar\\ baz
List the statistics: List the statistics::
dmsetup message vol 0 @stats_list dmsetup message vol 0 @stats_list
Print the statistics: Print the statistics::
dmsetup message vol 0 @stats_print 0 dmsetup message vol 0 @stats_print 0
Delete the statistics: Delete the statistics::
dmsetup message vol 0 @stats_delete 0 dmsetup message vol 0 @stats_delete 0

61
Documentation/device-mapper/striped.rst Normal file
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@ -0,0 +1,61 @@
=========
dm-stripe
=========
Device-Mapper's "striped" target is used to create a striped (i.e. RAID-0)
device across one or more underlying devices. Data is written in "chunks",
with consecutive chunks rotating among the underlying devices. This can
potentially provide improved I/O throughput by utilizing several physical
devices in parallel.
Parameters: <num devs> <chunk size> [<dev path> <offset>]+
<num devs>:
Number of underlying devices.
<chunk size>:
Size of each chunk of data. Must be at least as
large as the system's PAGE_SIZE.
<dev path>:
Full pathname to the underlying block-device, or a
"major:minor" device-number.
<offset>:
Starting sector within the device.
One or more underlying devices can be specified. The striped device size must
be a multiple of the chunk size multiplied by the number of underlying devices.
Example scripts
===============
::
#!/usr/bin/perl -w
# Create a striped device across any number of underlying devices. The device
# will be called "stripe_dev" and have a chunk-size of 128k.
my $chunk_size = 128 * 2;
my $dev_name = "stripe_dev";
my $num_devs = @ARGV;
my @devs = @ARGV;
my ($min_dev_size, $stripe_dev_size, $i);
if (!$num_devs) {
die("Specify at least one device\n");
}
$min_dev_size = `blockdev --getsz $devs[0]`;
for ($i = 1; $i < $num_devs; $i++) {
my $this_size = `blockdev --getsz $devs[$i]`;
$min_dev_size = ($min_dev_size < $this_size) ?
$min_dev_size : $this_size;
}
$stripe_dev_size = $min_dev_size * $num_devs;
$stripe_dev_size -= $stripe_dev_size % ($chunk_size * $num_devs);
$table = "0 $stripe_dev_size striped $num_devs $chunk_size";
for ($i = 0; $i < $num_devs; $i++) {
$table .= " $devs[$i] 0";
}
`echo $table | dmsetup create $dev_name`;

57
Documentation/device-mapper/striped.txt
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@ -1,57 +0,0 @@
dm-stripe
=========
Device-Mapper's "striped" target is used to create a striped (i.e. RAID-0)
device across one or more underlying devices. Data is written in "chunks",
with consecutive chunks rotating among the underlying devices. This can
potentially provide improved I/O throughput by utilizing several physical
devices in parallel.
Parameters: <num devs> <chunk size> [<dev path> <offset>]+
<num devs>: Number of underlying devices.
<chunk size>: Size of each chunk of data. Must be at least as
large as the system's PAGE_SIZE.
<dev path>: Full pathname to the underlying block-device, or a
"major:minor" device-number.
<offset>: Starting sector within the device.
One or more underlying devices can be specified. The striped device size must
be a multiple of the chunk size multiplied by the number of underlying devices.
Example scripts
===============
[[
#!/usr/bin/perl -w
# Create a striped device across any number of underlying devices. The device
# will be called "stripe_dev" and have a chunk-size of 128k.
my $chunk_size = 128 * 2;
my $dev_name = "stripe_dev";
my $num_devs = @ARGV;
my @devs = @ARGV;
my ($min_dev_size, $stripe_dev_size, $i);
if (!$num_devs) {
die("Specify at least one device\n");
}
$min_dev_size = `blockdev --getsz $devs[0]`;
for ($i = 1; $i < $num_devs; $i++) {
my $this_size = `blockdev --getsz $devs[$i]`;
$min_dev_size = ($min_dev_size < $this_size) ?
$min_dev_size : $this_size;
}
$stripe_dev_size = $min_dev_size * $num_devs;
$stripe_dev_size -= $stripe_dev_size % ($chunk_size * $num_devs);
$table = "0 $stripe_dev_size striped $num_devs $chunk_size";
for ($i = 0; $i < $num_devs; $i++) {
$table .= " $devs[$i] 0";
}
`echo $table | dmsetup create $dev_name`;
]]

47
Documentation/device-mapper/switch.txt → Documentation/device-mapper/switch.rst
View File

@ -1,3 +1,4 @@
=========
dm-switch dm-switch
========= =========
@ -67,27 +68,25 @@ b-tree can achieve.
Construction Parameters Construction Parameters
======================= =======================
<num_paths> <region_size> <num_optional_args> [<optional_args>...] <num_paths> <region_size> <num_optional_args> [<optional_args>...] [<dev_path> <offset>]+
[<dev_path> <offset>]+ <num_paths>
The number of paths across which to distribute the I/O.
<num_paths> <region_size>
The number of paths across which to distribute the I/O. The number of 512-byte sectors in a region. Each region can be redirected
to any of the available paths.
<region_size> <num_optional_args>
The number of 512-byte sectors in a region. Each region can be redirected The number of optional arguments. Currently, no optional arguments
to any of the available paths. are supported and so this must be zero.
<num_optional_args> <dev_path>
The number of optional arguments. Currently, no optional arguments The block device that represents a specific path to the device.
are supported and so this must be zero.
<dev_path> <offset>
The block device that represents a specific path to the device. The offset of the start of data on the specific <dev_path> (in units
of 512-byte sectors). This number is added to the sector number when
<offset> forwarding the request to the specific path. Typically it is zero.
The offset of the start of data on the specific <dev_path> (in units
of 512-byte sectors). This number is added to the sector number when
forwarding the request to the specific path. Typically it is zero.
Messages Messages
======== ========
@ -122,17 +121,21 @@ Example
Assume that you have volumes vg1/switch0 vg1/switch1 vg1/switch2 with Assume that you have volumes vg1/switch0 vg1/switch1 vg1/switch2 with
the same size. the same size.
Create a switch device with 64kB region size: Create a switch device with 64kB region size::
dmsetup create switch --table "0 `blockdev --getsz /dev/vg1/switch0` dmsetup create switch --table "0 `blockdev --getsz /dev/vg1/switch0`
switch 3 128 0 /dev/vg1/switch0 0 /dev/vg1/switch1 0 /dev/vg1/switch2 0" switch 3 128 0 /dev/vg1/switch0 0 /dev/vg1/switch1 0 /dev/vg1/switch2 0"
Set mappings for the first 7 entries to point to devices switch0, switch1, Set mappings for the first 7 entries to point to devices switch0, switch1,
switch2, switch0, switch1, switch2, switch1: switch2, switch0, switch1, switch2, switch1::
dmsetup message switch 0 set_region_mappings 0:0 :1 :2 :0 :1 :2 :1 dmsetup message switch 0 set_region_mappings 0:0 :1 :2 :0 :1 :2 :1
Set repetitive mapping. This command: Set repetitive mapping. This command::
dmsetup message switch 0 set_region_mappings 1000:1 :2 R2,10 dmsetup message switch 0 set_region_mappings 1000:1 :2 R2,10
is equivalent to:
is equivalent to::
dmsetup message switch 0 set_region_mappings 1000:1 :2 :1 :2 :1 :2 :1 :2 \ dmsetup message switch 0 set_region_mappings 1000:1 :2 :1 :2 :1 :2 :1 :2 \
:1 :2 :1 :2 :1 :2 :1 :2 :1 :2 :1 :2 :1 :2 :1 :2 :1 :2 :1 :2

68
Documentation/device-mapper/thin-provisioning.txt → Documentation/device-mapper/thin-provisioning.rst
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@ -1,3 +1,7 @@
=================
Thin provisioning
=================
Introduction Introduction
============ ============
@ -95,6 +99,8 @@ previously.)
Using an existing pool device Using an existing pool device
----------------------------- -----------------------------
::
dmsetup create pool \ dmsetup create pool \
--table "0 20971520 thin-pool $metadata_dev $data_dev \ --table "0 20971520 thin-pool $metadata_dev $data_dev \
$data_block_size $low_water_mark" $data_block_size $low_water_mark"
@ -154,7 +160,7 @@ Thin provisioning
i) Creating a new thinly-provisioned volume. i) Creating a new thinly-provisioned volume.
To create a new thinly- provisioned volume you must send a message to an To create a new thinly- provisioned volume you must send a message to an
active pool device, /dev/mapper/pool in this example. active pool device, /dev/mapper/pool in this example::
dmsetup message /dev/mapper/pool 0 "create_thin 0" dmsetup message /dev/mapper/pool 0 "create_thin 0"
@ -164,7 +170,7 @@ i) Creating a new thinly-provisioned volume.
ii) Using a thinly-provisioned volume. ii) Using a thinly-provisioned volume.
Thinly-provisioned volumes are activated using the 'thin' target: Thinly-provisioned volumes are activated using the 'thin' target::
dmsetup create thin --table "0 2097152 thin /dev/mapper/pool 0" dmsetup create thin --table "0 2097152 thin /dev/mapper/pool 0"
@ -181,6 +187,8 @@ i) Creating an internal snapshot.
must suspend it before creating the snapshot to avoid corruption. must suspend it before creating the snapshot to avoid corruption.
This is NOT enforced at the moment, so please be careful! This is NOT enforced at the moment, so please be careful!
::
dmsetup suspend /dev/mapper/thin dmsetup suspend /dev/mapper/thin
dmsetup message /dev/mapper/pool 0 "create_snap 1 0" dmsetup message /dev/mapper/pool 0 "create_snap 1 0"
dmsetup resume /dev/mapper/thin dmsetup resume /dev/mapper/thin
@ -198,14 +206,14 @@ ii) Using an internal snapshot.
activating or removing them both. (This differs from conventional activating or removing them both. (This differs from conventional
device-mapper snapshots.) device-mapper snapshots.)
Activate it exactly the same way as any other thinly-provisioned volume: Activate it exactly the same way as any other thinly-provisioned volume::
dmsetup create snap --table "0 2097152 thin /dev/mapper/pool 1" dmsetup create snap --table "0 2097152 thin /dev/mapper/pool 1"
External snapshots External snapshots
------------------ ------------------
You can use an external _read only_ device as an origin for a You can use an external **read only** device as an origin for a
thinly-provisioned volume. Any read to an unprovisioned area of the thinly-provisioned volume. Any read to an unprovisioned area of the
thin device will be passed through to the origin. Writes trigger thin device will be passed through to the origin. Writes trigger
the allocation of new blocks as usual. the allocation of new blocks as usual.
@ -223,11 +231,13 @@ i) Creating a snapshot of an external device
This is the same as creating a thin device. This is the same as creating a thin device.
You don't mention the origin at this stage. You don't mention the origin at this stage.
::
dmsetup message /dev/mapper/pool 0 "create_thin 0" dmsetup message /dev/mapper/pool 0 "create_thin 0"
ii) Using a snapshot of an external device. ii) Using a snapshot of an external device.
Append an extra parameter to the thin target specifying the origin: Append an extra parameter to the thin target specifying the origin::
dmsetup create snap --table "0 2097152 thin /dev/mapper/pool 0 /dev/image" dmsetup create snap --table "0 2097152 thin /dev/mapper/pool 0 /dev/image"
@ -240,6 +250,8 @@ Deactivation
All devices using a pool must be deactivated before the pool itself All devices using a pool must be deactivated before the pool itself
can be. can be.
::
dmsetup remove thin dmsetup remove thin
dmsetup remove snap dmsetup remove snap
dmsetup remove pool dmsetup remove pool
@ -252,25 +264,32 @@ Reference
i) Constructor i) Constructor
thin-pool <metadata dev> <data dev> <data block size (sectors)> \ ::
<low water mark (blocks)> [<number of feature args> [<arg>]*]
thin-pool <metadata dev> <data dev> <data block size (sectors)> \
<low water mark (blocks)> [<number of feature args> [<arg>]*]
Optional feature arguments: Optional feature arguments:
skip_block_zeroing: Skip the zeroing of newly-provisioned blocks. skip_block_zeroing:
Skip the zeroing of newly-provisioned blocks.
ignore_discard: Disable discard support. ignore_discard:
Disable discard support.
no_discard_passdown: Don't pass discards down to the underlying no_discard_passdown:
data device, but just remove the mapping. Don't pass discards down to the underlying
data device, but just remove the mapping.
read_only: Don't allow any changes to be made to the pool read_only:
Don't allow any changes to be made to the pool
metadata. This mode is only available after the metadata. This mode is only available after the
thin-pool has been created and first used in full thin-pool has been created and first used in full
read/write mode. It cannot be specified on initial read/write mode. It cannot be specified on initial
thin-pool creation. thin-pool creation.
error_if_no_space: Error IOs, instead of queueing, if no space. error_if_no_space:
Error IOs, instead of queueing, if no space.
Data block size must be between 64KB (128 sectors) and 1GB Data block size must be between 64KB (128 sectors) and 1GB
(2097152 sectors) inclusive. (2097152 sectors) inclusive.
@ -278,10 +297,12 @@ i) Constructor
ii) Status ii) Status
<transaction id> <used metadata blocks>/<total metadata blocks> ::
<used data blocks>/<total data blocks> <held metadata root>
ro|rw|out_of_data_space [no_]discard_passdown [error|queue]_if_no_space <transaction id> <used metadata blocks>/<total metadata blocks>
needs_check|- metadata_low_watermark <used data blocks>/<total data blocks> <held metadata root>
ro|rw|out_of_data_space [no_]discard_passdown [error|queue]_if_no_space
needs_check|- metadata_low_watermark
transaction id: transaction id:
A 64-bit number used by userspace to help synchronise with metadata A 64-bit number used by userspace to help synchronise with metadata
@ -336,13 +357,11 @@ ii) Status
iii) Messages iii) Messages
create_thin <dev id> create_thin <dev id>
Create a new thinly-provisioned device. Create a new thinly-provisioned device.
<dev id> is an arbitrary unique 24-bit identifier chosen by <dev id> is an arbitrary unique 24-bit identifier chosen by
the caller. the caller.
create_snap <dev id> <origin id> create_snap <dev id> <origin id>
Create a new snapshot of another thinly-provisioned device. Create a new snapshot of another thinly-provisioned device.
<dev id> is an arbitrary unique 24-bit identifier chosen by <dev id> is an arbitrary unique 24-bit identifier chosen by
the caller. the caller.
@ -350,11 +369,9 @@ iii) Messages
of which the new device will be a snapshot. of which the new device will be a snapshot.
delete <dev id> delete <dev id>
Deletes a thin device. Irreversible. Deletes a thin device. Irreversible.
set_transaction_id <current id> <new id> set_transaction_id <current id> <new id>
Userland volume managers, such as LVM, need a way to Userland volume managers, such as LVM, need a way to
synchronise their external metadata with the internal metadata of the synchronise their external metadata with the internal metadata of the
pool target. The thin-pool target offers to store an pool target. The thin-pool target offers to store an
@ -364,14 +381,12 @@ iii) Messages
compare-and-swap message. compare-and-swap message.
reserve_metadata_snap reserve_metadata_snap
Reserve a copy of the data mapping btree for use by userland. Reserve a copy of the data mapping btree for use by userland.
This allows userland to inspect the mappings as they were when This allows userland to inspect the mappings as they were when
this message was executed. Use the pool's status command to this message was executed. Use the pool's status command to
get the root block associated with the metadata snapshot. get the root block associated with the metadata snapshot.
release_metadata_snap release_metadata_snap
Release a previously reserved copy of the data mapping btree. Release a previously reserved copy of the data mapping btree.
'thin' target 'thin' target
@ -379,7 +394,9 @@ iii) Messages
i) Constructor i) Constructor
thin <pool dev> <dev id> [<external origin dev>] ::
thin <pool dev> <dev id> [<external origin dev>]
pool dev: pool dev:
the thin-pool device, e.g. /dev/mapper/my_pool or 253:0 the thin-pool device, e.g. /dev/mapper/my_pool or 253:0
@ -401,8 +418,7 @@ provisioned as and when needed.
ii) Status ii) Status
<nr mapped sectors> <highest mapped sector> <nr mapped sectors> <highest mapped sector>
If the pool has encountered device errors and failed, the status If the pool has encountered device errors and failed, the status
will just contain the string 'Fail'. The userspace recovery will just contain the string 'Fail'. The userspace recovery
tools should then be used. tools should then be used.

93
Documentation/device-mapper/unstriped.txt → Documentation/device-mapper/unstriped.rst
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@ -1,3 +1,7 @@
================================
Device-mapper "unstriped" target
================================
Introduction Introduction
============ ============
@ -34,46 +38,46 @@ striped target to combine the 4 devices into one. It then will use
the unstriped target ontop of the striped device to access the the unstriped target ontop of the striped device to access the
individual backing loop devices. We write data to the newly exposed individual backing loop devices. We write data to the newly exposed
unstriped devices and verify the data written matches the correct unstriped devices and verify the data written matches the correct
underlying device on the striped array. underlying device on the striped array::
#!/bin/bash #!/bin/bash
MEMBER_SIZE=$((128 * 1024 * 1024)) MEMBER_SIZE=$((128 * 1024 * 1024))
NUM=4 NUM=4
SEQ_END=$((${NUM}-1)) SEQ_END=$((${NUM}-1))
CHUNK=256 CHUNK=256
BS=4096 BS=4096
RAID_SIZE=$((${MEMBER_SIZE}*${NUM}/512)) RAID_SIZE=$((${MEMBER_SIZE}*${NUM}/512))
DM_PARMS="0 ${RAID_SIZE} striped ${NUM} ${CHUNK}" DM_PARMS="0 ${RAID_SIZE} striped ${NUM} ${CHUNK}"
COUNT=$((${MEMBER_SIZE} / ${BS})) COUNT=$((${MEMBER_SIZE} / ${BS}))
for i in $(seq 0 ${SEQ_END}); do for i in $(seq 0 ${SEQ_END}); do
dd if=/dev/zero of=member-${i} bs=${MEMBER_SIZE} count=1 oflag=direct dd if=/dev/zero of=member-${i} bs=${MEMBER_SIZE} count=1 oflag=direct
losetup /dev/loop${i} member-${i} losetup /dev/loop${i} member-${i}
DM_PARMS+=" /dev/loop${i} 0" DM_PARMS+=" /dev/loop${i} 0"
done done
echo $DM_PARMS | dmsetup create raid0 echo $DM_PARMS | dmsetup create raid0
for i in $(seq 0 ${SEQ_END}); do for i in $(seq 0 ${SEQ_END}); do
echo "0 1 unstriped ${NUM} ${CHUNK} ${i} /dev/mapper/raid0 0" | dmsetup create set-${i} echo "0 1 unstriped ${NUM} ${CHUNK} ${i} /dev/mapper/raid0 0" | dmsetup create set-${i}
done; done;
for i in $(seq 0 ${SEQ_END}); do for i in $(seq 0 ${SEQ_END}); do
dd if=/dev/urandom of=/dev/mapper/set-${i} bs=${BS} count=${COUNT} oflag=direct dd if=/dev/urandom of=/dev/mapper/set-${i} bs=${BS} count=${COUNT} oflag=direct
diff /dev/mapper/set-${i} member-${i} diff /dev/mapper/set-${i} member-${i}
done; done;
for i in $(seq 0 ${SEQ_END}); do for i in $(seq 0 ${SEQ_END}); do
dmsetup remove set-${i} dmsetup remove set-${i}
done done
dmsetup remove raid0 dmsetup remove raid0
for i in $(seq 0 ${SEQ_END}); do for i in $(seq 0 ${SEQ_END}); do
losetup -d /dev/loop${i} losetup -d /dev/loop${i}
rm -f member-${i} rm -f member-${i}
done done
Another example Another example
--------------- ---------------
@ -81,7 +85,7 @@ Another example
Intel NVMe drives contain two cores on the physical device. Intel NVMe drives contain two cores on the physical device.
Each core of the drive has segregated access to its LBA range. Each core of the drive has segregated access to its LBA range.
The current LBA model has a RAID 0 128k chunk on each core, resulting The current LBA model has a RAID 0 128k chunk on each core, resulting
in a 256k stripe across the two cores: in a 256k stripe across the two cores::
Core 0: Core 1: Core 0: Core 1:
__________ __________ __________ __________
@ -108,17 +112,24 @@ Example dmsetup usage
unstriped ontop of Intel NVMe device that has 2 cores unstriped ontop of Intel NVMe device that has 2 cores
----------------------------------------------------- -----------------------------------------------------
dmsetup create nvmset0 --table '0 512 unstriped 2 256 0 /dev/nvme0n1 0'
dmsetup create nvmset1 --table '0 512 unstriped 2 256 1 /dev/nvme0n1 0' ::
dmsetup create nvmset0 --table '0 512 unstriped 2 256 0 /dev/nvme0n1 0'
dmsetup create nvmset1 --table '0 512 unstriped 2 256 1 /dev/nvme0n1 0'
There will now be two devices that expose Intel NVMe core 0 and 1 There will now be two devices that expose Intel NVMe core 0 and 1
respectively: respectively::
/dev/mapper/nvmset0
/dev/mapper/nvmset1 /dev/mapper/nvmset0
/dev/mapper/nvmset1
unstriped ontop of striped with 4 drives using 128K chunk size unstriped ontop of striped with 4 drives using 128K chunk size
-------------------------------------------------------------- --------------------------------------------------------------
dmsetup create raid_disk0 --table '0 512 unstriped 4 256 0 /dev/mapper/striped 0'
dmsetup create raid_disk1 --table '0 512 unstriped 4 256 1 /dev/mapper/striped 0' ::
dmsetup create raid_disk2 --table '0 512 unstriped 4 256 2 /dev/mapper/striped 0'
dmsetup create raid_disk3 --table '0 512 unstriped 4 256 3 /dev/mapper/striped 0' dmsetup create raid_disk0 --table '0 512 unstriped 4 256 0 /dev/mapper/striped 0'
dmsetup create raid_disk1 --table '0 512 unstriped 4 256 1 /dev/mapper/striped 0'
dmsetup create raid_disk2 --table '0 512 unstriped 4 256 2 /dev/mapper/striped 0'
dmsetup create raid_disk3 --table '0 512 unstriped 4 256 3 /dev/mapper/striped 0'

20
Documentation/device-mapper/verity.txt → Documentation/device-mapper/verity.rst
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@ -1,5 +1,6 @@
=========
dm-verity dm-verity
========== =========
Device-Mapper's "verity" target provides transparent integrity checking of Device-Mapper's "verity" target provides transparent integrity checking of
block devices using a cryptographic digest provided by the kernel crypto API. block devices using a cryptographic digest provided by the kernel crypto API.
@ -7,6 +8,9 @@ This target is read-only.
Construction Parameters Construction Parameters
======================= =======================
::
<version> <dev> <hash_dev> <version> <dev> <hash_dev>
<data_block_size> <hash_block_size> <data_block_size> <hash_block_size>
<num_data_blocks> <hash_start_block> <num_data_blocks> <hash_start_block>
@ -160,7 +164,9 @@ calculating the parent node.
The tree looks something like: The tree looks something like:
alg = sha256, num_blocks = 32768, block_size = 4096 alg = sha256, num_blocks = 32768, block_size = 4096
::
[ root ] [ root ]
/ . . . \ / . . . \
@ -189,6 +195,7 @@ block boundary) are the hash blocks which are stored a depth at a time
The full specification of kernel parameters and on-disk metadata format The full specification of kernel parameters and on-disk metadata format
is available at the cryptsetup project's wiki page is available at the cryptsetup project's wiki page
https://gitlab.com/cryptsetup/cryptsetup/wikis/DMVerity https://gitlab.com/cryptsetup/cryptsetup/wikis/DMVerity
Status Status
@ -198,7 +205,8 @@ If any check failed, C (for Corruption) is returned.
Example Example
======= =======
Set up a device: Set up a device::
# dmsetup create vroot --readonly --table \ # dmsetup create vroot --readonly --table \
"0 2097152 verity 1 /dev/sda1 /dev/sda2 4096 4096 262144 1 sha256 "\ "0 2097152 verity 1 /dev/sda1 /dev/sda2 4096 4096 262144 1 sha256 "\
"4392712ba01368efdf14b05c76f9e4df0d53664630b5d48632ed17a137f39076 "\ "4392712ba01368efdf14b05c76f9e4df0d53664630b5d48632ed17a137f39076 "\
@ -209,11 +217,13 @@ the hash tree or activate the kernel device. This is available from
the cryptsetup upstream repository https://gitlab.com/cryptsetup/cryptsetup/ the cryptsetup upstream repository https://gitlab.com/cryptsetup/cryptsetup/
(as a libcryptsetup extension). (as a libcryptsetup extension).
Create hash on the device: Create hash on the device::
# veritysetup format /dev/sda1 /dev/sda2 # veritysetup format /dev/sda1 /dev/sda2
... ...
Root hash: 4392712ba01368efdf14b05c76f9e4df0d53664630b5d48632ed17a137f39076 Root hash: 4392712ba01368efdf14b05c76f9e4df0d53664630b5d48632ed17a137f39076
Activate the device: Activate the device::
# veritysetup create vroot /dev/sda1 /dev/sda2 \ # veritysetup create vroot /dev/sda1 /dev/sda2 \
4392712ba01368efdf14b05c76f9e4df0d53664630b5d48632ed17a137f39076 4392712ba01368efdf14b05c76f9e4df0d53664630b5d48632ed17a137f39076

13
Documentation/device-mapper/writecache.txt → Documentation/device-mapper/writecache.rst
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@ -1,3 +1,7 @@
=================
Writecache target
=================
The writecache target caches writes on persistent memory or on SSD. It The writecache target caches writes on persistent memory or on SSD. It
doesn't cache reads because reads are supposed to be cached in page cache doesn't cache reads because reads are supposed to be cached in page cache
in normal RAM. in normal RAM.
@ -6,15 +10,18 @@ When the device is constructed, the first sector should be zeroed or the
first sector should contain valid superblock from previous invocation. first sector should contain valid superblock from previous invocation.
Constructor parameters: Constructor parameters:
1. type of the cache device - "p" or "s" 1. type of the cache device - "p" or "s"
p - persistent memory
s - SSD - p - persistent memory
- s - SSD
2. the underlying device that will be cached 2. the underlying device that will be cached
3. the cache device 3. the cache device
4. block size (4096 is recommended; the maximum block size is the page 4. block size (4096 is recommended; the maximum block size is the page
size) size)
5. the number of optional parameters (the parameters with an argument 5. the number of optional parameters (the parameters with an argument
count as two) count as two)
start_sector n (default: 0) start_sector n (default: 0)
offset from the start of cache device in 512-byte sectors offset from the start of cache device in 512-byte sectors
high_watermark n (default: 50) high_watermark n (default: 50)
@ -43,6 +50,7 @@ Constructor parameters:
applicable only to persistent memory - don't use the FUA applicable only to persistent memory - don't use the FUA
flag when writing back data and send the FLUSH request flag when writing back data and send the FLUSH request
afterwards afterwards
- some underlying devices perform better with fua, some - some underlying devices perform better with fua, some
with nofua. The user should test it with nofua. The user should test it
@ -60,6 +68,7 @@ Messages:
flush the cache device on next suspend. Use this message flush the cache device on next suspend. Use this message
when you are going to remove the cache device. The proper when you are going to remove the cache device. The proper
sequence for removing the cache device is: sequence for removing the cache device is:
1. send the "flush_on_suspend" message 1. send the "flush_on_suspend" message
2. load an inactive table with a linear target that maps 2. load an inactive table with a linear target that maps
to the underlying device to the underlying device

14
Documentation/device-mapper/zero.txt → Documentation/device-mapper/zero.rst
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@ -1,3 +1,4 @@
=======
dm-zero dm-zero
======= =======
@ -18,20 +19,19 @@ filesystem limitations.
To create a sparse device, start by creating a dm-zero device that's the To create a sparse device, start by creating a dm-zero device that's the
desired size of the sparse device. For this example, we'll assume a 10TB desired size of the sparse device. For this example, we'll assume a 10TB
sparse device. sparse device::
TEN_TERABYTES=`expr 10 \* 1024 \* 1024 \* 1024 \* 2` # 10 TB in sectors TEN_TERABYTES=`expr 10 \* 1024 \* 1024 \* 1024 \* 2` # 10 TB in sectors
echo "0 $TEN_TERABYTES zero" | dmsetup create zero1 echo "0 $TEN_TERABYTES zero" | dmsetup create zero1
Then create a snapshot of the zero device, using any available block-device as Then create a snapshot of the zero device, using any available block-device as
the COW device. The size of the COW device will determine the amount of real the COW device. The size of the COW device will determine the amount of real
space available to the sparse device. For this example, we'll assume /dev/sdb1 space available to the sparse device. For this example, we'll assume /dev/sdb1
is an available 10GB partition. is an available 10GB partition::
echo "0 $TEN_TERABYTES snapshot /dev/mapper/zero1 /dev/sdb1 p 128" | \ echo "0 $TEN_TERABYTES snapshot /dev/mapper/zero1 /dev/sdb1 p 128" | \
dmsetup create sparse1 dmsetup create sparse1
This will create a 10TB sparse device called /dev/mapper/sparse1 that has This will create a 10TB sparse device called /dev/mapper/sparse1 that has
10GB of actual storage space available. If more than 10GB of data is written 10GB of actual storage space available. If more than 10GB of data is written
to this device, it will start returning I/O errors. to this device, it will start returning I/O errors.

7
Documentation/devicetree/bindings/net/fsl-enetc.txt
View File

@ -16,8 +16,8 @@ Required properties:
In this case, the ENETC node should include a "mdio" sub-node In this case, the ENETC node should include a "mdio" sub-node
that in turn should contain the "ethernet-phy" node describing the that in turn should contain the "ethernet-phy" node describing the
external phy. Below properties are required, their bindings external phy. Below properties are required, their bindings
already defined in ethernet.txt or phy.txt, under already defined in Documentation/devicetree/bindings/net/ethernet.txt or
Documentation/devicetree/bindings/net/*. Documentation/devicetree/bindings/net/phy.txt.
Required: Required:
@ -51,8 +51,7 @@ Example:
connection: connection:
In this case, the ENETC port node defines a fixed link connection, In this case, the ENETC port node defines a fixed link connection,
as specified by "fixed-link.txt", under as specified by Documentation/devicetree/bindings/net/fixed-link.txt.
Documentation/devicetree/bindings/net/*.
Required: Required:

2
Documentation/devicetree/bindings/pci/amlogic,meson-pcie.txt
View File

@ -3,7 +3,7 @@ Amlogic Meson AXG DWC PCIE SoC controller
Amlogic Meson PCIe host controller is based on the Synopsys DesignWare PCI core. Amlogic Meson PCIe host controller is based on the Synopsys DesignWare PCI core.
It shares common functions with the PCIe DesignWare core driver and It shares common functions with the PCIe DesignWare core driver and
inherits common properties defined in inherits common properties defined in
Documentation/devicetree/bindings/pci/designware-pci.txt. Documentation/devicetree/bindings/pci/designware-pcie.txt.
Additional properties are described here: Additional properties are described here:

2
Documentation/devicetree/bindings/regulator/qcom,rpmh-regulator.txt
View File

@ -97,7 +97,7 @@ Second Level Nodes - Regulators
sent for this regulator including those which are for a sent for this regulator including those which are for a
strictly lower power state. strictly lower power state.
Other properties defined in Documentation/devicetree/bindings/regulator.txt Other properties defined in Documentation/devicetree/bindings/regulator/regulator.txt
may also be used. regulator-initial-mode and regulator-allowed-modes may be may also be used. regulator-initial-mode and regulator-allowed-modes may be
specified for VRM regulators using mode values from specified for VRM regulators using mode values from
include/dt-bindings/regulator/qcom,rpmh-regulator.h. regulator-allow-bypass include/dt-bindings/regulator/qcom,rpmh-regulator.h. regulator-allow-bypass

2
Documentation/devicetree/booting-without-of.txt
View File

@ -277,7 +277,7 @@ it with special cases.
the decompressor (the real mode entry point goes to the same 32bit the decompressor (the real mode entry point goes to the same 32bit
entry point once it switched into protected mode). That entry point entry point once it switched into protected mode). That entry point
supports one calling convention which is documented in supports one calling convention which is documented in
Documentation/x86/boot.txt Documentation/x86/boot.rst
The physical pointer to the device-tree block (defined in chapter II) The physical pointer to the device-tree block (defined in chapter II)
is passed via setup_data which requires at least boot protocol 2.09. is passed via setup_data which requires at least boot protocol 2.09.
The type filed is defined as The type filed is defined as

2
Documentation/doc-guide/kernel-doc.rst
View File

@ -359,7 +359,7 @@ Domain`_ references.
``monospaced font``. ``monospaced font``.
Useful if you need to use special characters that would otherwise have some Useful if you need to use special characters that would otherwise have some
meaning either by kernel-doc script of by reStructuredText. meaning either by kernel-doc script or by reStructuredText.
This is particularly useful if you need to use things like ``%ph`` inside This is particularly useful if you need to use things like ``%ph`` inside
a function description. a function description.

30
Documentation/doc-guide/sphinx.rst
View File

@ -27,8 +27,7 @@ Sphinx Install
============== ==============
The ReST markups currently used by the Documentation/ files are meant to be The ReST markups currently used by the Documentation/ files are meant to be
built with ``Sphinx`` version 1.3 or higher. If you desire to build built with ``Sphinx`` version 1.3 or higher.
PDF output, it is recommended to use version 1.4.6 or higher.
There's a script that checks for the Sphinx requirements. Please see There's a script that checks for the Sphinx requirements. Please see
:ref:`sphinx-pre-install` for further details. :ref:`sphinx-pre-install` for further details.
@ -56,13 +55,13 @@ or ``virtualenv``, depending on how your distribution packaged Python 3.
those expressions are written using LaTeX notation. It needs texlive those expressions are written using LaTeX notation. It needs texlive
installed with amdfonts and amsmath in order to evaluate them. installed with amdfonts and amsmath in order to evaluate them.
In summary, if you want to install Sphinx version 1.4.9, you should do:: In summary, if you want to install Sphinx version 1.7.9, you should do::
$ virtualenv sphinx_1.4 $ virtualenv sphinx_1.7.9
$ . sphinx_1.4/bin/activate $ . sphinx_1.7.9/bin/activate
(sphinx_1.4) $ pip install -r Documentation/sphinx/requirements.txt (sphinx_1.7.9) $ pip install -r Documentation/sphinx/requirements.txt
After running ``. sphinx_1.4/bin/activate``, the prompt will change, After running ``. sphinx_1.7.9/bin/activate``, the prompt will change,
in order to indicate that you're using the new environment. If you in order to indicate that you're using the new environment. If you
open a new shell, you need to rerun this command to enter again at open a new shell, you need to rerun this command to enter again at
the virtual environment before building the documentation. the virtual environment before building the documentation.
@ -105,8 +104,8 @@ command line options for your distro::
You should run: You should run:
sudo dnf install -y texlive-luatex85 sudo dnf install -y texlive-luatex85
/usr/bin/virtualenv sphinx_1.4 /usr/bin/virtualenv sphinx_1.7.9
. sphinx_1.4/bin/activate . sphinx_1.7.9/bin/activate
pip install -r Documentation/sphinx/requirements.txt pip install -r Documentation/sphinx/requirements.txt
Can't build as 1 mandatory dependency is missing at ./scripts/sphinx-pre-install line 468. Can't build as 1 mandatory dependency is missing at ./scripts/sphinx-pre-install line 468.
@ -218,7 +217,7 @@ Here are some specific guidelines for the kernel documentation:
examples, etc.), use ``::`` for anything that doesn't really benefit examples, etc.), use ``::`` for anything that doesn't really benefit
from syntax highlighting, especially short snippets. Use from syntax highlighting, especially short snippets. Use
``.. code-block:: <language>`` for longer code blocks that benefit ``.. code-block:: <language>`` for longer code blocks that benefit
from highlighting. from highlighting. For a short snippet of code embedded in the text, use \`\`.
the C domain the C domain
@ -242,11 +241,14 @@ The C domain of the kernel-doc has some additional features. E.g. you can
The func-name (e.g. ioctl) remains in the output but the ref-name changed from The func-name (e.g. ioctl) remains in the output but the ref-name changed from
``ioctl`` to ``VIDIOC_LOG_STATUS``. The index entry for this function is also ``ioctl`` to ``VIDIOC_LOG_STATUS``. The index entry for this function is also
changed to ``VIDIOC_LOG_STATUS`` and the function can now referenced by: changed to ``VIDIOC_LOG_STATUS``.
.. code-block:: rst Please note that there is no need to use ``c:func:`` to generate cross
references to function documentation. Due to some Sphinx extension magic,
:c:func:`VIDIOC_LOG_STATUS` the documentation build system will automatically turn a reference to
``function()`` into a cross reference if an index entry for the given
function name exists. If you see ``c:func:`` use in a kernel document,
please feel free to remove it.
list tables list tables

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