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This was a reasonably active cycle for documentation; this pull includes: 

- Some kernel-doc cleanups.  That script is still regex onslaught from
    hell, but it has gotten a little better.
 
  - Improvements to the checkpatch docs, which are also used by the tool
    itself.
 
  - A major update to the pathname lookup documentation.
 
  - Elimination of :doc: markup, since our automarkup magic can create
    references from filenames without all the extra noise.
 
  - The flurry of Chinese translation activity continues.
 
 Plus, of course, the usual collection of updates, typo fixes, and warning
 fixes.
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Merge tag 'docs-5.14' of git://git.lwn.net/linux

Pull documentation updates from Jonathan Corbet:
 "This was a reasonably active cycle for documentation; this includes:

   - Some kernel-doc cleanups. That script is still regex onslaught from
     hell, but it has gotten a little better.

   - Improvements to the checkpatch docs, which are also used by the
     tool itself.

   - A major update to the pathname lookup documentation.

   - Elimination of :doc: markup, since our automarkup magic can create
     references from filenames without all the extra noise.

   - The flurry of Chinese translation activity continues.

  Plus, of course, the usual collection of updates, typo fixes, and
  warning fixes"

* tag 'docs-5.14' of git://git.lwn.net/linux: (115 commits)
  docs: path-lookup: use bare function() rather than literals
  docs: path-lookup: update symlink description
  docs: path-lookup: update get_link() ->follow_link description
  docs: path-lookup: update WALK_GET, WALK_PUT desc
  docs: path-lookup: no get_link()
  docs: path-lookup: update i_op->put_link and cookie description
  docs: path-lookup: i_op->follow_link replaced with i_op->get_link
  docs: path-lookup: Add macro name to symlink limit description
  docs: path-lookup: remove filename_mountpoint
  docs: path-lookup: update do_last() part
  docs: path-lookup: update path_mountpoint() part
  docs: path-lookup: update path_to_nameidata() part
  docs: path-lookup: update follow_managed() part
  docs: Makefile: Use CONFIG_SHELL not SHELL
  docs: Take a little noise out of the build process
  docs: x86: avoid using ReST :doc:`foo` markup
  docs: virt: kvm: s390-pv-boot.rst: avoid using ReST :doc:`foo` markup
  docs: userspace-api: landlock.rst: avoid using ReST :doc:`foo` markup
  docs: trace: ftrace.rst: avoid using ReST :doc:`foo` markup
  docs: trace: coresight: coresight.rst: avoid using ReST :doc:`foo` markup
  ...
This commit is contained in:
Linus Torvalds 2021-06-28 16:53:05 -07:00
parent 122fa8c588 98cf495184
commit 233a806b00
147 changed files with 5725 additions and 1081 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
Documentation/ABI/obsolete/sysfs-cpuidle
View File

@ -6,4 +6,4 @@ Description:
with the update that cpuidle governor can be changed at runtime in default,
both current_governor and current_governor_ro co-exist under
/sys/devices/system/cpu/cpuidle/ file, it's duplicate so make
current_governor_ro obselete.
current_governor_ro obsolete.

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

@ -5,7 +5,7 @@ Contact: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Description:
The /sys/kernel/uids/<uid>/cpu_shares tunable is used
to set the cpu bandwidth a user is allowed. This is a
propotional value. What that means is that if there
proportional value. What that means is that if there
are two users logged in, each with an equal number of
shares, then they will get equal CPU bandwidth. Another
example would be, if User A has shares = 1024 and user

2
Documentation/ABI/stable/sysfs-bus-vmbus
View File

@ -61,7 +61,7 @@ Date: September. 2017
KernelVersion: 4.14
Contact: Stephen Hemminger <sthemmin@microsoft.com>
Description: Directory for per-channel information
NN is the VMBUS relid associtated with the channel.
NN is the VMBUS relid associated with the channel.
What: /sys/bus/vmbus/devices/<UUID>/channels/<N>/cpu
Date: September. 2017

2
Documentation/ABI/stable/sysfs-bus-xen-backend
View File

@ -19,7 +19,7 @@ Date: April 2011
KernelVersion: 3.0
Contact: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Description:
The major:minor number (in hexidecimal) of the
The major:minor number (in hexadecimal) of the
physical device providing the storage for this backend
block device.

83
Documentation/ABI/stable/sysfs-devices-system-cpu
View File

@ -23,3 +23,86 @@ Description: Default value for the Data Stream Control Register (DSCR) on
here).
If set by a process it will be inherited by child processes.
Values: 64 bit unsigned integer (bit field)
What: /sys/devices/system/cpu/cpuX/topology/physical_package_id
Description: physical package id of cpuX. Typically corresponds to a physical
socket number, but the actual value is architecture and platform
dependent.
Values: integer
What: /sys/devices/system/cpu/cpuX/topology/die_id
Description: the CPU die ID of cpuX. Typically it is the hardware platform's
identifier (rather than the kernel's). The actual value is
architecture and platform dependent.
Values: integer
What: /sys/devices/system/cpu/cpuX/topology/core_id
Description: the CPU core ID of cpuX. Typically it is the hardware platform's
identifier (rather than the kernel's). The actual value is
architecture and platform dependent.
Values: integer
What: /sys/devices/system/cpu/cpuX/topology/book_id
Description: the book ID of cpuX. Typically it is the hardware platform's
identifier (rather than the kernel's). The actual value is
architecture and platform dependent. it's only used on s390.
Values: integer
What: /sys/devices/system/cpu/cpuX/topology/drawer_id
Description: the drawer ID of cpuX. Typically it is the hardware platform's
identifier (rather than the kernel's). The actual value is
architecture and platform dependent. it's only used on s390.
Values: integer
What: /sys/devices/system/cpu/cpuX/topology/core_cpus
Description: internal kernel map of CPUs within the same core.
(deprecated name: "thread_siblings")
Values: hexadecimal bitmask.
What: /sys/devices/system/cpu/cpuX/topology/core_cpus_list
Description: human-readable list of CPUs within the same core.
The format is like 0-3, 8-11, 14,17.
(deprecated name: "thread_siblings_list").
Values: decimal list.
What: /sys/devices/system/cpu/cpuX/topology/package_cpus
Description: internal kernel map of the CPUs sharing the same physical_package_id.
(deprecated name: "core_siblings").
Values: hexadecimal bitmask.
What: /sys/devices/system/cpu/cpuX/topology/package_cpus_list
Description: human-readable list of CPUs sharing the same physical_package_id.
The format is like 0-3, 8-11, 14,17.
(deprecated name: "core_siblings_list")
Values: decimal list.
What: /sys/devices/system/cpu/cpuX/topology/die_cpus
Description: internal kernel map of CPUs within the same die.
Values: hexadecimal bitmask.
What: /sys/devices/system/cpu/cpuX/topology/die_cpus_list
Description: human-readable list of CPUs within the same die.
The format is like 0-3, 8-11, 14,17.
Values: decimal list.
What: /sys/devices/system/cpu/cpuX/topology/book_siblings
Description: internal kernel map of cpuX's hardware threads within the same
book_id. it's only used on s390.
Values: hexadecimal bitmask.
What: /sys/devices/system/cpu/cpuX/topology/book_siblings_list
Description: human-readable list of cpuX's hardware threads within the same
book_id.
The format is like 0-3, 8-11, 14,17. it's only used on s390.
Values: decimal list.
What: /sys/devices/system/cpu/cpuX/topology/drawer_siblings
Description: internal kernel map of cpuX's hardware threads within the same
drawer_id. it's only used on s390.
Values: hexadecimal bitmask.
What: /sys/devices/system/cpu/cpuX/topology/drawer_siblings_list
Description: human-readable list of cpuX's hardware threads within the same
drawer_id.
The format is like 0-3, 8-11, 14,17. it's only used on s390.
Values: decimal list.

2
Documentation/ABI/stable/sysfs-driver-dma-idxd
View File

@ -173,7 +173,7 @@ What: /sys/bus/dsa/devices/wq<m>.<n>/priority
Date: Oct 25, 2019
KernelVersion: 5.6.0
Contact: dmaengine@vger.kernel.org
Description: The priority value of this work queue, it is a vlue relative to
Description: The priority value of this work queue, it is a value relative to
other work queue in the same group to control quality of service
for dispatching work from multiple workqueues in the same group.

4
Documentation/ABI/stable/sysfs-driver-mlxreg-io
View File

@ -137,7 +137,7 @@ Contact: Vadim Pasternak <vadimpmellanox.com>
Description: These files show the system reset cause, as following:
COMEX thermal shutdown; wathchdog power off or reset was derived
by one of the next components: COMEX, switch board or by Small Form
Factor mezzanine, reset requested from ASIC, reset cuased by BIOS
Factor mezzanine, reset requested from ASIC, reset caused by BIOS
reload. Value 1 in file means this is reset cause, 0 - otherwise.
Only one of the above causes could be 1 at the same time, representing
only last reset cause.
@ -183,7 +183,7 @@ What: /sys/devices/platform/mlxplat/mlxreg-io/hwmon/hwmon*/vpd_wp
Date: January 2020
KernelVersion: 5.6
Contact: Vadim Pasternak <vadimpmellanox.com>
Description: This file allows to overwrite system VPD hardware wrtie
Description: This file allows to overwrite system VPD hardware write
protection when attribute is set 1.
The file is read/write.

2
Documentation/ABI/testing/configfs-iio
View File

@ -31,4 +31,4 @@ Date: April 2016
KernelVersion: 4.7
Description:
Dummy IIO devices directory. Creating a directory here will result
in creating a dummy IIO device in the IIO subystem.
in creating a dummy IIO device in the IIO subsystem.

8
Documentation/ABI/testing/configfs-most
View File

@ -20,7 +20,7 @@ Description:
subbuffer_size
configure the sub-buffer size for this channel
(needed for synchronous and isochrnous data)
(needed for synchronous and isochronous data)
num_buffers
@ -75,7 +75,7 @@ Description:
subbuffer_size
configure the sub-buffer size for this channel
(needed for synchronous and isochrnous data)
(needed for synchronous and isochronous data)
num_buffers
@ -130,7 +130,7 @@ Description:
subbuffer_size
configure the sub-buffer size for this channel
(needed for synchronous and isochrnous data)
(needed for synchronous and isochronous data)
num_buffers
@ -196,7 +196,7 @@ Description:
subbuffer_size
configure the sub-buffer size for this channel
(needed for synchronous and isochrnous data)
(needed for synchronous and isochronous data)
num_buffers

2
Documentation/ABI/testing/configfs-usb-gadget
View File

@ -137,7 +137,7 @@ Description:
This group contains "OS String" extension handling attributes.
============= ===============================================
use flag turning "OS Desctiptors" support on/off
use flag turning "OS Descriptors" support on/off
b_vendor_code one-byte value used for custom per-device and
per-interface requests
qw_sign an identifier to be reported as "OS String"

4
Documentation/ABI/testing/configfs-usb-gadget-uvc
View File

@ -170,7 +170,7 @@ Description: Default color matching descriptors
bMatrixCoefficients matrix used to compute luma and
chroma values from the color primaries
bTransferCharacteristics optoelectronic transfer
characteristic of the source picutre,
characteristic of the source picture,
also called the gamma function
bColorPrimaries color primaries and the reference
white
@ -311,7 +311,7 @@ Description: Specific streaming header descriptors
a hardware trigger interrupt event
bTriggerSupport flag specifying if hardware
triggering is supported
bStillCaptureMethod method of still image caputre
bStillCaptureMethod method of still image capture
supported
bTerminalLink id of the output terminal to which
the video endpoint of this interface

2
Documentation/ABI/testing/debugfs-driver-genwqe
View File

@ -31,7 +31,7 @@ What: /sys/kernel/debug/genwqe/genwqe<n>_card/prev_regs
Date: Oct 2013
Contact: haver@linux.vnet.ibm.com
Description: Dump of the error registers before the last reset of
the card occured.
the card occurred.
Only available for PF.
What: /sys/kernel/debug/genwqe/genwqe<n>_card/prev_dbg_uid0

2
Documentation/ABI/testing/debugfs-driver-habanalabs
View File

@ -153,7 +153,7 @@ KernelVersion: 5.1
Contact: ogabbay@kernel.org
Description: Triggers an I2C transaction that is generated by the device's
CPU. Writing to this file generates a write transaction while
reading from the file generates a read transcation
reading from the file generates a read transaction
What: /sys/kernel/debug/habanalabs/hl<n>/i2c_reg
Date: Jan 2019

2
Documentation/ABI/testing/sysfs-bus-fsi
View File

@ -12,7 +12,7 @@ KernelVersion: 4.12
Contact: linux-fsi@lists.ozlabs.org
Description:
Sends an FSI BREAK command on a master's communication
link to any connnected slaves. A BREAK resets connected
link to any connected slaves. A BREAK resets connected
device's logic and preps it to receive further commands
from the master.

6
Documentation/ABI/testing/sysfs-bus-iio
View File

@ -786,7 +786,7 @@ What: /sys/.../events/in_capacitanceY_adaptive_thresh_rising_en
What: /sys/.../events/in_capacitanceY_adaptive_thresh_falling_en
KernelVersion: 5.13
Contact: linux-iio@vger.kernel.org
Descrption:
Description:
Adaptive thresholds are similar to normal fixed thresholds
but the value is expressed as an offset from a value which
provides a low frequency approximation of the channel itself.
@ -798,10 +798,10 @@ What: /sys/.../in_capacitanceY_adaptive_thresh_rising_timeout
What: /sys/.../in_capacitanceY_adaptive_thresh_falling_timeout
KernelVersion: 5.11
Contact: linux-iio@vger.kernel.org
Descrption:
Description:
When adaptive thresholds are used, the tracking signal
may adjust too slowly to step changes in the raw signal.
*_timeout (in seconds) specifies a time for which the
Thus these specify the time in seconds for which the
difference between the slow tracking signal and the raw
signal is allowed to remain out-of-range before a reset
event occurs in which the tracking signal is made equal

4
Documentation/ABI/testing/sysfs-bus-pci
View File

@ -139,8 +139,8 @@ Description:
binary file containing the Vital Product Data for the
device. It should follow the VPD format defined in
PCI Specification 2.1 or 2.2, but users should consider
that some devices may have malformatted data. If the
underlying VPD has a writable section then the
that some devices may have incorrectly formatted data.
If the underlying VPD has a writable section then the
corresponding section of this file will be writable.
What: /sys/bus/pci/devices/.../virtfnN

100
Documentation/ABI/testing/sysfs-class-backlight
View File

@ -84,3 +84,103 @@ Description:
It can be enabled by writing the value stored in
/sys/class/backlight/<backlight>/max_brightness to
/sys/class/backlight/<backlight>/brightness.
What: /sys/class/backlight/<backlight>/<ambient light zone>_max
Date: Sep, 2009
KernelVersion: v2.6.32
Contact: device-drivers-devel@blackfin.uclinux.org
Description:
Control the maximum brightness for <ambient light zone>
on this <backlight>. Values are between 0 and 127. This file
will also show the brightness level stored for this
<ambient light zone>.
The <ambient light zone> is device-driver specific:
For ADP5520 and ADP5501, <ambient light zone> can be:
=========== ================================================
Ambient sysfs entry
light zone
=========== ================================================
daylight /sys/class/backlight/<backlight>/daylight_max
office /sys/class/backlight/<backlight>/office_max
dark /sys/class/backlight/<backlight>/dark_max
=========== ================================================
For ADP8860, <ambient light zone> can be:
=========== ================================================
Ambient sysfs entry
light zone
=========== ================================================
l1_daylight /sys/class/backlight/<backlight>/l1_daylight_max
l2_office /sys/class/backlight/<backlight>/l2_office_max
l3_dark /sys/class/backlight/<backlight>/l3_dark_max
=========== ================================================
For ADP8870, <ambient light zone> can be:
=========== ================================================
Ambient sysfs entry
light zone
=========== ================================================
l1_daylight /sys/class/backlight/<backlight>/l1_daylight_max
l2_bright /sys/class/backlight/<backlight>/l2_bright_max
l3_office /sys/class/backlight/<backlight>/l3_office_max
l4_indoor /sys/class/backlight/<backlight>/l4_indoor_max
l5_dark /sys/class/backlight/<backlight>/l5_dark_max
=========== ================================================
See also: /sys/class/backlight/<backlight>/ambient_light_zone.
What: /sys/class/backlight/<backlight>/<ambient light zone>_dim
Date: Sep, 2009
KernelVersion: v2.6.32
Contact: device-drivers-devel@blackfin.uclinux.org
Description:
Control the dim brightness for <ambient light zone>
on this <backlight>. Values are between 0 and 127, typically
set to 0. Full off when the backlight is disabled.
This file will also show the dim brightness level stored for
this <ambient light zone>.
The <ambient light zone> is device-driver specific:
For ADP5520 and ADP5501, <ambient light zone> can be:
=========== ================================================
Ambient sysfs entry
light zone
=========== ================================================
daylight /sys/class/backlight/<backlight>/daylight_dim
office /sys/class/backlight/<backlight>/office_dim
dark /sys/class/backlight/<backlight>/dark_dim
=========== ================================================
For ADP8860, <ambient light zone> can be:
=========== ================================================
Ambient sysfs entry
light zone
=========== ================================================
l1_daylight /sys/class/backlight/<backlight>/l1_daylight_dim
l2_office /sys/class/backlight/<backlight>/l2_office_dim
l3_dark /sys/class/backlight/<backlight>/l3_dark_dim
=========== ================================================
For ADP8870, <ambient light zone> can be:
=========== ================================================
Ambient sysfs entry
light zone
=========== ================================================
l1_daylight /sys/class/backlight/<backlight>/l1_daylight_dim
l2_bright /sys/class/backlight/<backlight>/l2_bright_dim
l3_office /sys/class/backlight/<backlight>/l3_office_dim
l4_indoor /sys/class/backlight/<backlight>/l4_indoor_dim
l5_dark /sys/class/backlight/<backlight>/l5_dark_dim
=========== ================================================
See also: /sys/class/backlight/<backlight>/ambient_light_zone.

31
Documentation/ABI/testing/sysfs-class-backlight-adp5520
View File

@ -1,31 +0,0 @@
sysfs interface for analog devices adp5520(01) backlight driver
---------------------------------------------------------------
The backlight brightness control operates at three different levels for the
adp5520 and adp5501 devices: daylight (level 1), office (level 2) and dark
(level 3). By default the brightness operates at the daylight brightness level.
What: /sys/class/backlight/<backlight>/daylight_max
What: /sys/class/backlight/<backlight>/office_max
What: /sys/class/backlight/<backlight>/dark_max
Date: Sep, 2009
KernelVersion: v2.6.32
Contact: Michael Hennerich <michael.hennerich@analog.com>
Description:
(RW) Maximum current setting for the backlight when brightness
is at one of the three levels (daylight, office or dark). This
is an input code between 0 and 127, which is transformed to a
value between 0 mA and 30 mA using linear or non-linear
algorithms.
What: /sys/class/backlight/<backlight>/daylight_dim
What: /sys/class/backlight/<backlight>/office_dim
What: /sys/class/backlight/<backlight>/dark_dim
Date: Sep, 2009
KernelVersion: v2.6.32
Contact: Michael Hennerich <michael.hennerich@analog.com>
Description:
(RW) Dim current setting for the backlight when brightness is at
one of the three levels (daylight, office or dark). This is an
input code between 0 and 127, which is transformed to a value
between 0 mA and 30 mA using linear or non-linear algorithms.

37
Documentation/ABI/testing/sysfs-class-backlight-adp8860
View File

@ -1,37 +0,0 @@
sysfs interface for analog devices adp8860 backlight driver
-----------------------------------------------------------
The backlight brightness control operates at three different levels for the
adp8860, adp8861 and adp8863 devices: daylight (level 1), office (level 2) and
dark (level 3). By default the brightness operates at the daylight brightness
level.
See also /sys/class/backlight/<backlight>/ambient_light_level and
/sys/class/backlight/<backlight>/ambient_light_zone.
What: /sys/class/backlight/<backlight>/l1_daylight_max
What: /sys/class/backlight/<backlight>/l2_office_max
What: /sys/class/backlight/<backlight>/l3_dark_max
Date: Apr, 2010
KernelVersion: v2.6.35
Contact: Michael Hennerich <michael.hennerich@analog.com>
Description:
(RW) Maximum current setting for the backlight when brightness
is at one of the three levels (daylight, office or dark). This
is an input code between 0 and 127, which is transformed to a
value between 0 mA and 30 mA using linear or non-linear
algorithms.
What: /sys/class/backlight/<backlight>/l1_daylight_dim
What: /sys/class/backlight/<backlight>/l2_office_dim
What: /sys/class/backlight/<backlight>/l3_dark_dim
Date: Apr, 2010
KernelVersion: v2.6.35
Contact: Michael Hennerich <michael.hennerich@analog.com>
Description:
(RW) Dim current setting for the backlight when brightness is at
one of the three levels (daylight, office or dark). This is an
input code between 0 and 127, which is transformed to a value
between 0 mA and 30 mA using linear or non-linear algorithms.

32
Documentation/ABI/testing/sysfs-class-backlight-driver-adp8870
View File

@ -1,32 +0,0 @@
See also /sys/class/backlight/<backlight>/ambient_light_level and
/sys/class/backlight/<backlight>/ambient_light_zone.
What: /sys/class/backlight/<backlight>/<ambient light zone>_max
What: /sys/class/backlight/<backlight>/l1_daylight_max
What: /sys/class/backlight/<backlight>/l2_bright_max
What: /sys/class/backlight/<backlight>/l3_office_max
What: /sys/class/backlight/<backlight>/l4_indoor_max
What: /sys/class/backlight/<backlight>/l5_dark_max
Date: May 2011
KernelVersion: 3.0
Contact: device-drivers-devel@blackfin.uclinux.org
Description:
Control the maximum brightness for <ambient light zone>
on this <backlight>. Values are between 0 and 127. This file
will also show the brightness level stored for this
<ambient light zone>.
What: /sys/class/backlight/<backlight>/<ambient light zone>_dim
What: /sys/class/backlight/<backlight>/l2_bright_dim
What: /sys/class/backlight/<backlight>/l3_office_dim
What: /sys/class/backlight/<backlight>/l4_indoor_dim
What: /sys/class/backlight/<backlight>/l5_dark_dim
Date: May 2011
KernelVersion: 3.0
Contact: device-drivers-devel@blackfin.uclinux.org
Description:
Control the dim brightness for <ambient light zone>
on this <backlight>. Values are between 0 and 127, typically
set to 0. Full off when the backlight is disabled.
This file will also show the dim brightness level stored for
this <ambient light zone>.

9
Documentation/ABI/testing/sysfs-class-led-driver-el15203000
View File

@ -1,9 +0,0 @@
What: /sys/class/leds/<led>/repeat
Date: September 2019
KernelVersion: 5.5
Description:
EL15203000 supports only indefinitely patterns,
so this file should always store -1.
For more info, please see:
Documentation/ABI/testing/sysfs-class-led-trigger-pattern

3
Documentation/ABI/testing/sysfs-class-led-trigger-pattern
View File

@ -35,3 +35,6 @@ Description:
This file will always return the originally written repeat
number.
It should be noticed that some leds, like EL15203000 may
only support indefinitely patterns, so they always store -1.

8
Documentation/ABI/testing/sysfs-devices-system-cpu
View File

@ -97,7 +97,7 @@ Description: CPU topology files that describe a logical CPU's relationship
corresponds to a physical socket number, but the actual value
is architecture and platform dependent.
thread_siblings: internel kernel map of cpu#'s hardware
thread_siblings: internal kernel map of cpu#'s hardware
threads within the same core as cpu#
thread_siblings_list: human-readable list of cpu#'s hardware
@ -280,7 +280,7 @@ Description: Disable L3 cache indices
on a processor with this functionality will return the currently
disabled index for that node. There is one L3 structure per
node, or per internal node on MCM machines. Writing a valid
index to one of these files will cause the specificed cache
index to one of these files will cause the specified cache
index to be disabled.
All AMD processors with L3 caches provide this functionality.
@ -295,7 +295,7 @@ Description: Processor frequency boosting control
This switch controls the boost setting for the whole system.
Boosting allows the CPU and the firmware to run at a frequency
beyound it's nominal limit.
beyond it's nominal limit.
More details can be found in
Documentation/admin-guide/pm/cpufreq.rst
@ -532,7 +532,7 @@ What: /sys/devices/system/cpu/smt
/sys/devices/system/cpu/smt/control
Date: June 2018
Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org>
Description: Control Symetric Multi Threading (SMT)
Description: Control Symmetric Multi Threading (SMT)
active: Tells whether SMT is active (enabled and siblings online)

4
Documentation/ABI/testing/sysfs-driver-ufs
View File

@ -168,7 +168,7 @@ Description: This file shows the manufacturing date in BCD format.
What: /sys/bus/platform/drivers/ufshcd/*/device_descriptor/manufacturer_id
Date: February 2018
Contact: Stanislav Nijnikov <stanislav.nijnikov@wdc.com>
Description: This file shows the manufacturee ID. This is one of the
Description: This file shows the manufacturer ID. This is one of the
UFS device descriptor parameters. The full information about
the descriptor could be found at UFS specifications 2.1.
@ -521,7 +521,7 @@ Description: This file shows maximum VCC, VCCQ and VCCQ2 value for
What: /sys/bus/platform/drivers/ufshcd/*/string_descriptors/manufacturer_name
Date: February 2018
Contact: Stanislav Nijnikov <stanislav.nijnikov@wdc.com>
Description: This file contains a device manufactureer name string.
Description: This file contains a device manufacturer name string.
The full information about the descriptor could be found at
UFS specifications 2.1.

2
Documentation/ABI/testing/sysfs-fs-f2fs
View File

@ -238,7 +238,7 @@ Description: Shows current reserved blocks in system, it may be temporarily
What: /sys/fs/f2fs/<disk>/gc_urgent
Date: August 2017
Contact: "Jaegeuk Kim" <jaegeuk@kernel.org>
Description: Do background GC agressively when set. When gc_urgent = 1,
Description: Do background GC aggressively when set. When gc_urgent = 1,
background thread starts to do GC by given gc_urgent_sleep_time
interval. When gc_urgent = 2, F2FS will lower the bar of
checking idle in order to process outstanding discard commands

12
Documentation/ABI/testing/sysfs-kernel-iommu_groups
View File

@ -25,14 +25,10 @@ Description: /sys/kernel/iommu_groups/reserved_regions list IOVA
the base IOVA, the second is the end IOVA and the third
field describes the type of the region.
What: /sys/kernel/iommu_groups/reserved_regions
Date: June 2019
KernelVersion: v5.3
Contact: Eric Auger <eric.auger@redhat.com>
Description: In case an RMRR is used only by graphics or USB devices
it is now exposed as "direct-relaxable" instead of "direct".
In device assignment use case, for instance, those RMRR
are considered to be relaxable and safe.
Since kernel 5.3, in case an RMRR is used only by graphics or
USB devices it is now exposed as "direct-relaxable" instead
of "direct". In device assignment use case, for instance,
those RMRR are considered to be relaxable and safe.
What: /sys/kernel/iommu_groups/<grp_id>/type
Date: November 2020

2
Documentation/Makefile
View File

@ -76,7 +76,7 @@ quiet_cmd_sphinx = SPHINX $@ --> file://$(abspath $(BUILDDIR)/$3/$4)
PYTHONDONTWRITEBYTECODE=1 \
BUILDDIR=$(abspath $(BUILDDIR)) SPHINX_CONF=$(abspath $(srctree)/$(src)/$5/$(SPHINX_CONF)) \
$(PYTHON3) $(srctree)/scripts/jobserver-exec \
$(SHELL) $(srctree)/Documentation/sphinx/parallel-wrapper.sh \
$(CONFIG_SHELL) $(srctree)/Documentation/sphinx/parallel-wrapper.sh \
$(SPHINXBUILD) \
-b $2 \
-c $(abspath $(srctree)/$(src)) \

18
Documentation/PCI/acpi-info.rst
View File

@ -22,9 +22,9 @@ or if the device has INTx interrupts connected by platform interrupt
controllers and a _PRT is needed to describe those connections.
ACPI resource description is done via _CRS objects of devices in the ACPI
namespace [2].   The _CRS is like a generalized PCI BAR: the OS can read
namespace [2]. The _CRS is like a generalized PCI BAR: the OS can read
_CRS and figure out what resource is being consumed even if it doesn't have
a driver for the device [3].  That's important because it means an old OS
a driver for the device [3]. That's important because it means an old OS
can work correctly even on a system with new devices unknown to the OS.
The new devices might not do anything, but the OS can at least make sure no
resources conflict with them.
@ -41,15 +41,15 @@ ACPI, that device will have a specific _HID/_CID that tells the OS what
driver to bind to it, and the _CRS tells the OS and the driver where the
device's registers are.
PCI host bridges are PNP0A03 or PNP0A08 devices.  Their _CRS should
describe all the address space they consume.  This includes all the windows
PCI host bridges are PNP0A03 or PNP0A08 devices. Their _CRS should
describe all the address space they consume. This includes all the windows
they forward down to the PCI bus, as well as registers of the host bridge
itself that are not forwarded to PCI.  The host bridge registers include
itself that are not forwarded to PCI. The host bridge registers include
things like secondary/subordinate bus registers that determine the bus
range below the bridge, window registers that describe the apertures, etc.
These are all device-specific, non-architected things, so the only way a
PNP0A03/PNP0A08 driver can manage them is via _PRS/_CRS/_SRS, which contain
the device-specific details.  The host bridge registers also include ECAM
the device-specific details. The host bridge registers also include ECAM
space, since it is consumed by the host bridge.
ACPI defines a Consumer/Producer bit to distinguish the bridge registers
@ -66,7 +66,7 @@ the PNP0A03/PNP0A08 device itself. The workaround was to describe the
bridge registers (including ECAM space) in PNP0C02 catch-all devices [6].
With the exception of ECAM, the bridge register space is device-specific
anyway, so the generic PNP0A03/PNP0A08 driver (pci_root.c) has no need to
know about it.  
know about it.
New architectures should be able to use "Consumer" Extended Address Space
descriptors in the PNP0A03 device for bridge registers, including ECAM,
@ -75,9 +75,9 @@ ia64 kernels assume all address space descriptors, including "Consumer"
Extended Address Space ones, are windows, so it would not be safe to
describe bridge registers this way on those architectures.
PNP0C02 "motherboard" devices are basically a catch-all.  There's no
PNP0C02 "motherboard" devices are basically a catch-all. There's no
programming model for them other than "don't use these resources for
anything else."  So a PNP0C02 _CRS should claim any address space that is
anything else." So a PNP0C02 _CRS should claim any address space that is
(1) not claimed by _CRS under any other device object in the ACPI namespace
and (2) should not be assigned by the OS to something else.

2
Documentation/PCI/endpoint/pci-endpoint-cfs.rst
View File

@ -125,4 +125,4 @@ all the EPF devices are created and linked with the EPC device.
| interrupt_pin
| function
[1] :doc:`pci-endpoint`
[1] Documentation/PCI/endpoint/pci-endpoint.rst

6
Documentation/PCI/pci.rst
View File

@ -265,7 +265,7 @@ Set the DMA mask size
---------------------
.. note::
If anything below doesn't make sense, please refer to
:doc:`/core-api/dma-api`. This section is just a reminder that
Documentation/core-api/dma-api.rst. This section is just a reminder that
drivers need to indicate DMA capabilities of the device and is not
an authoritative source for DMA interfaces.
@ -291,7 +291,7 @@ Many 64-bit "PCI" devices (before PCI-X) and some PCI-X devices are
Setup shared control data
-------------------------
Once the DMA masks are set, the driver can allocate "consistent" (a.k.a. shared)
memory. See :doc:`/core-api/dma-api` for a full description of
memory. See Documentation/core-api/dma-api.rst for a full description of
the DMA APIs. This section is just a reminder that it needs to be done
before enabling DMA on the device.
@ -421,7 +421,7 @@ owners if there is one.
Then clean up "consistent" buffers which contain the control data.
See :doc:`/core-api/dma-api` for details on unmapping interfaces.
See Documentation/core-api/dma-api.rst for details on unmapping interfaces.
Unregister from other subsystems

83
Documentation/admin-guide/cputopology.rst
View File

@ -2,87 +2,10 @@
How CPU topology info is exported via sysfs
===========================================
Export CPU topology info via sysfs. Items (attributes) are similar
CPU topology info is exported via sysfs. Items (attributes) are similar
to /proc/cpuinfo output of some architectures. They reside in
/sys/devices/system/cpu/cpuX/topology/:
physical_package_id:
physical package id of cpuX. Typically corresponds to a physical
socket number, but the actual value is architecture and platform
dependent.
die_id:
the CPU die ID of cpuX. Typically it is the hardware platform's
identifier (rather than the kernel's). The actual value is
architecture and platform dependent.
core_id:
the CPU core ID of cpuX. Typically it is the hardware platform's
identifier (rather than the kernel's). The actual value is
architecture and platform dependent.
book_id:
the book ID of cpuX. Typically it is the hardware platform's
identifier (rather than the kernel's). The actual value is
architecture and platform dependent.
drawer_id:
the drawer ID of cpuX. Typically it is the hardware platform's
identifier (rather than the kernel's). The actual value is
architecture and platform dependent.
core_cpus:
internal kernel map of CPUs within the same core.
(deprecated name: "thread_siblings")
core_cpus_list:
human-readable list of CPUs within the same core.
(deprecated name: "thread_siblings_list");
package_cpus:
internal kernel map of the CPUs sharing the same physical_package_id.
(deprecated name: "core_siblings")
package_cpus_list:
human-readable list of CPUs sharing the same physical_package_id.
(deprecated name: "core_siblings_list")
die_cpus:
internal kernel map of CPUs within the same die.
die_cpus_list:
human-readable list of CPUs within the same die.
book_siblings:
internal kernel map of cpuX's hardware threads within the same
book_id.
book_siblings_list:
human-readable list of cpuX's hardware threads within the same
book_id.
drawer_siblings:
internal kernel map of cpuX's hardware threads within the same
drawer_id.
drawer_siblings_list:
human-readable list of cpuX's hardware threads within the same
drawer_id.
/sys/devices/system/cpu/cpuX/topology/. Please refer to the ABI file:
Documentation/ABI/stable/sysfs-devices-system-cpu.
Architecture-neutral, drivers/base/topology.c, exports these attributes.
However, the book and drawer related sysfs files will only be created if

2
Documentation/admin-guide/ext4.rst
View File

@ -392,7 +392,7 @@ When mounting an ext4 filesystem, the following option are accepted:
dax
Use direct access (no page cache). See
Documentation/filesystems/dax.txt. Note that this option is
Documentation/filesystems/dax.rst. Note that this option is
incompatible with data=journal.
inlinecrypt

3
Documentation/admin-guide/hw-vuln/special-register-buffer-data-sampling.rst
View File

@ -3,7 +3,8 @@
SRBDS - Special Register Buffer Data Sampling
=============================================
SRBDS is a hardware vulnerability that allows MDS :doc:`mds` techniques to
SRBDS is a hardware vulnerability that allows MDS
Documentation/admin-guide/hw-vuln/mds.rst techniques to
infer values returned from special register accesses. Special register
accesses are accesses to off core registers. According to Intel's evaluation,
the special register reads that have a security expectation of privacy are

138
Documentation/admin-guide/kdump/kdump.rst
View File

@ -2,7 +2,7 @@
Documentation for Kdump - The kexec-based Crash Dumping Solution
================================================================
This document includes overview, setup and installation, and analysis
This document includes overview, setup, installation, and analysis
information.
Overview
@ -13,9 +13,9 @@ dump of the system kernel's memory needs to be taken (for example, when
the system panics). The system kernel's memory image is preserved across
the reboot and is accessible to the dump-capture kernel.
You can use common commands, such as cp and scp, to copy the
memory image to a dump file on the local disk, or across the network to
a remote system.
You can use common commands, such as cp, scp or makedumpfile to copy
the memory image to a dump file on the local disk, or across the network
to a remote system.
Kdump and kexec are currently supported on the x86, x86_64, ppc64, ia64,
s390x, arm and arm64 architectures.
@ -26,13 +26,15 @@ the dump-capture kernel. This ensures that ongoing Direct Memory Access
The kexec -p command loads the dump-capture kernel into this reserved
memory.
On x86 machines, the first 640 KB of physical memory is needed to boot,
regardless of where the kernel loads. Therefore, kexec backs up this
region just before rebooting into the dump-capture kernel.
On x86 machines, the first 640 KB of physical memory is needed for boot,
regardless of where the kernel loads. For simpler handling, the whole
low 1M is reserved to avoid any later kernel or device driver writing
data into this area. Like this, the low 1M can be reused as system RAM
by kdump kernel without extra handling.
Similarly on PPC64 machines first 32KB of physical memory is needed for
booting regardless of where the kernel is loaded and to support 64K page
size kexec backs up the first 64KB memory.
On PPC64 machines first 32KB of physical memory is needed for booting
regardless of where the kernel is loaded and to support 64K page size
kexec backs up the first 64KB memory.
For s390x, when kdump is triggered, the crashkernel region is exchanged
with the region [0, crashkernel region size] and then the kdump kernel
@ -46,14 +48,14 @@ passed to the dump-capture kernel through the elfcorehdr= boot
parameter. Optionally the size of the ELF header can also be passed
when using the elfcorehdr=[size[KMG]@]offset[KMG] syntax.
With the dump-capture kernel, you can access the memory image through
/proc/vmcore. This exports the dump as an ELF-format file that you can
write out using file copy commands such as cp or scp. Further, you can
use analysis tools such as the GNU Debugger (GDB) and the Crash tool to
debug the dump file. This method ensures that the dump pages are correctly
ordered.
write out using file copy commands such as cp or scp. You can also use
makedumpfile utility to analyze and write out filtered contents with
options, e.g with '-d 31' it will only write out kernel data. Further,
you can use analysis tools such as the GNU Debugger (GDB) and the Crash
tool to debug the dump file. This method ensures that the dump pages are
correctly ordered.
Setup and Installation
======================
@ -125,9 +127,18 @@ dump-capture kernels for enabling kdump support.
System kernel config options
----------------------------
1) Enable "kexec system call" in "Processor type and features."::
1) Enable "kexec system call" or "kexec file based system call" in
"Processor type and features."::
CONFIG_KEXEC=y
CONFIG_KEXEC=y or CONFIG_KEXEC_FILE=y
And both of them will select KEXEC_CORE::
CONFIG_KEXEC_CORE=y
Subsequently, CRASH_CORE is selected by KEXEC_CORE::
CONFIG_CRASH_CORE=y
2) Enable "sysfs file system support" in "Filesystem" -> "Pseudo
filesystems." This is usually enabled by default::
@ -175,17 +186,19 @@ Dump-capture kernel config options (Arch Dependent, i386 and x86_64)
CONFIG_HIGHMEM4G
2) On i386 and x86_64, disable symmetric multi-processing support
under "Processor type and features"::
2) With CONFIG_SMP=y, usually nr_cpus=1 need specified on the kernel
command line when loading the dump-capture kernel because one
CPU is enough for kdump kernel to dump vmcore on most of systems.
CONFIG_SMP=n
However, you can also specify nr_cpus=X to enable multiple processors
in kdump kernel. In this case, "disable_cpu_apicid=" is needed to
tell kdump kernel which cpu is 1st kernel's BSP. Please refer to
admin-guide/kernel-parameters.txt for more details.
(If CONFIG_SMP=y, then specify maxcpus=1 on the kernel command line
when loading the dump-capture kernel, see section "Load the Dump-capture
Kernel".)
With CONFIG_SMP=n, the above things are not related.
3) If one wants to build and use a relocatable kernel,
Enable "Build a relocatable kernel" support under "Processor type and
3) A relocatable kernel is suggested to be built by default. If not yet,
enable "Build a relocatable kernel" support under "Processor type and
features"::
CONFIG_RELOCATABLE=y
@ -241,10 +254,6 @@ Dump-capture kernel config options (Arch Dependent, ia64)
crashkernel=256M
If the start address is specified, note that the start address of the
kernel will be aligned to 64Mb, so if the start address is not then
any space below the alignment point will be wasted.
Dump-capture kernel config options (Arch Dependent, arm)
----------------------------------------------------------
@ -260,8 +269,31 @@ Dump-capture kernel config options (Arch Dependent, arm64)
on non-VHE systems even if it is configured. This is because the CPU
will not be reset to EL2 on panic.
Extended crashkernel syntax
crashkernel syntax
===========================
1) crashkernel=size@offset
Here 'size' specifies how much memory to reserve for the dump-capture kernel
and 'offset' specifies the beginning of this reserved memory. For example,
"crashkernel=64M@16M" tells the system kernel to reserve 64 MB of memory
starting at physical address 0x01000000 (16MB) for the dump-capture kernel.
The crashkernel region can be automatically placed by the system
kernel at run time. This is done by specifying the base address as 0,
or omitting it all together::
crashkernel=256M@0
or::
crashkernel=256M
If the start address is specified, note that the start address of the
kernel will be aligned to a value (which is Arch dependent), so if the
start address is not then any space below the alignment point will be
wasted.
2) range1:size1[,range2:size2,...][@offset]
While the "crashkernel=size[@offset]" syntax is sufficient for most
configurations, sometimes it's handy to have the reserved memory dependent
@ -285,21 +317,34 @@ This would mean:
2) if the RAM size is between 512M and 2G (exclusive), then reserve 64M
3) if the RAM size is larger than 2G, then reserve 128M
3) crashkernel=size,high and crashkernel=size,low
If memory above 4G is preferred, crashkernel=size,high can be used to
fulfill that. With it, physical memory is allowed to be allocated from top,
so could be above 4G if system has more than 4G RAM installed. Otherwise,
memory region will be allocated below 4G if available.
When crashkernel=X,high is passed, kernel could allocate physical memory
region above 4G, low memory under 4G is needed in this case. There are
three ways to get low memory:
1) Kernel will allocate at least 256M memory below 4G automatically
if crashkernel=Y,low is not specified.
2) Let user specify low memory size instead.
3) Specified value 0 will disable low memory allocation::
crashkernel=0,low
Boot into System Kernel
=======================
-----------------------
1) Update the boot loader (such as grub, yaboot, or lilo) configuration
files as necessary.
2) Boot the system kernel with the boot parameter "crashkernel=Y@X",
where Y specifies how much memory to reserve for the dump-capture kernel
and X specifies the beginning of this reserved memory. For example,
"crashkernel=64M@16M" tells the system kernel to reserve 64 MB of memory
starting at physical address 0x01000000 (16MB) for the dump-capture kernel.
2) Boot the system kernel with the boot parameter "crashkernel=Y@X".
On x86 and x86_64, use "crashkernel=64M@16M".
On x86 and x86_64, use "crashkernel=Y[@X]". Most of the time, the
start address 'X' is not necessary, kernel will search a suitable
area. Unless an explicit start address is expected.
On ppc64, use "crashkernel=128M@32M".
@ -331,8 +376,8 @@ of dump-capture kernel. Following is the summary.
For i386 and x86_64:
- Use vmlinux if kernel is not relocatable.
- Use bzImage/vmlinuz if kernel is relocatable.
- Use vmlinux if kernel is not relocatable.
For ppc64:
@ -392,7 +437,7 @@ loading dump-capture kernel.
For i386, x86_64 and ia64:
"1 irqpoll maxcpus=1 reset_devices"
"1 irqpoll nr_cpus=1 reset_devices"
For ppc64:
@ -400,7 +445,7 @@ For ppc64:
For s390x:
"1 maxcpus=1 cgroup_disable=memory"
"1 nr_cpus=1 cgroup_disable=memory"
For arm:
@ -408,7 +453,7 @@ For arm:
For arm64:
"1 maxcpus=1 reset_devices"
"1 nr_cpus=1 reset_devices"
Notes on loading the dump-capture kernel:
@ -488,6 +533,10 @@ the following command::
cp /proc/vmcore <dump-file>
You can also use makedumpfile utility to write out the dump file
with specified options to filter out unwanted contents, e.g::
makedumpfile -l --message-level 1 -d 31 /proc/vmcore <dump-file>
Analysis
========
@ -535,8 +584,7 @@ This will cause a kdump to occur at the add_taint()->panic() call.
Contact
=======
- Vivek Goyal (vgoyal@redhat.com)
- Maneesh Soni (maneesh@in.ibm.com)
- kexec@lists.infradead.org
GDB macros
==========

3
Documentation/admin-guide/kernel-parameters.txt
View File

@ -3513,6 +3513,9 @@
nr_uarts= [SERIAL] maximum number of UARTs to be registered.
numa=off [KNL, ARM64, PPC, RISCV, SPARC, X86] Disable NUMA, Only
set up a single NUMA node spanning all memory.
numa_balancing= [KNL,ARM64,PPC,RISCV,S390,X86] Enable or disable automatic
NUMA balancing.
Allowed values are enable and disable

16
Documentation/admin-guide/pm/intel_idle.rst
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@ -20,8 +20,8 @@ Nehalem and later generations of Intel processors, but the level of support for
a particular processor model in it depends on whether or not it recognizes that
processor model and may also depend on information coming from the platform
firmware. [To understand ``intel_idle`` it is necessary to know how ``CPUIdle``
works in general, so this is the time to get familiar with :doc:`cpuidle` if you
have not done that yet.]
works in general, so this is the time to get familiar with
Documentation/admin-guide/pm/cpuidle.rst if you have not done that yet.]
``intel_idle`` uses the ``MWAIT`` instruction to inform the processor that the
logical CPU executing it is idle and so it may be possible to put some of the
@ -53,7 +53,8 @@ processor) corresponding to them depends on the processor model and it may also
depend on the configuration of the platform.
In order to create a list of available idle states required by the ``CPUIdle``
subsystem (see :ref:`idle-states-representation` in :doc:`cpuidle`),
subsystem (see :ref:`idle-states-representation` in
Documentation/admin-guide/pm/cpuidle.rst),
``intel_idle`` can use two sources of information: static tables of idle states
for different processor models included in the driver itself and the ACPI tables
of the system. The former are always used if the processor model at hand is
@ -98,7 +99,8 @@ states may not be enabled by default if there are no matching entries in the
preliminary list of idle states coming from the ACPI tables. In that case user
space still can enable them later (on a per-CPU basis) with the help of
the ``disable`` idle state attribute in ``sysfs`` (see
:ref:`idle-states-representation` in :doc:`cpuidle`). This basically means that
:ref:`idle-states-representation` in
Documentation/admin-guide/pm/cpuidle.rst). This basically means that
the idle states "known" to the driver may not be enabled by default if they have
not been exposed by the platform firmware (through the ACPI tables).
@ -186,7 +188,8 @@ be desirable. In practice, it is only really necessary to do that if the idle
states in question cannot be enabled during system startup, because in the
working state of the system the CPU power management quality of service (PM
QoS) feature can be used to prevent ``CPUIdle`` from touching those idle states
even if they have been enumerated (see :ref:`cpu-pm-qos` in :doc:`cpuidle`).
even if they have been enumerated (see :ref:`cpu-pm-qos` in
Documentation/admin-guide/pm/cpuidle.rst).
Setting ``max_cstate`` to 0 causes the ``intel_idle`` initialization to fail.
The ``no_acpi`` and ``use_acpi`` module parameters (recognized by ``intel_idle``
@ -202,7 +205,8 @@ Namely, the positions of the bits that are set in the ``states_off`` value are
the indices of idle states to be disabled by default (as reflected by the names
of the corresponding idle state directories in ``sysfs``, :file:`state0`,
:file:`state1` ... :file:`state<i>` ..., where ``<i>`` is the index of the given
idle state; see :ref:`idle-states-representation` in :doc:`cpuidle`).
idle state; see :ref:`idle-states-representation` in
Documentation/admin-guide/pm/cpuidle.rst).
For example, if ``states_off`` is equal to 3, the driver will disable idle
states 0 and 1 by default, and if it is equal to 8, idle state 3 will be

9
Documentation/admin-guide/pm/intel_pstate.rst
View File

@ -18,8 +18,8 @@ General Information
(``CPUFreq``). It is a scaling driver for the Sandy Bridge and later
generations of Intel processors. Note, however, that some of those processors
may not be supported. [To understand ``intel_pstate`` it is necessary to know
how ``CPUFreq`` works in general, so this is the time to read :doc:`cpufreq` if
you have not done that yet.]
how ``CPUFreq`` works in general, so this is the time to read
Documentation/admin-guide/pm/cpufreq.rst if you have not done that yet.]
For the processors supported by ``intel_pstate``, the P-state concept is broader
than just an operating frequency or an operating performance point (see the
@ -445,8 +445,9 @@ Interpretation of Policy Attributes
-----------------------------------
The interpretation of some ``CPUFreq`` policy attributes described in
:doc:`cpufreq` is special with ``intel_pstate`` as the current scaling driver
and it generally depends on the driver's `operation mode <Operation Modes_>`_.
Documentation/admin-guide/pm/cpufreq.rst is special with ``intel_pstate``
as the current scaling driver and it generally depends on the driver's
`operation mode <Operation Modes_>`_.
First of all, the values of the ``cpuinfo_max_freq``, ``cpuinfo_min_freq`` and
``scaling_cur_freq`` attributes are produced by applying a processor-specific

2
Documentation/admin-guide/reporting-issues.rst
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@ -1248,7 +1248,7 @@ paragraph makes the severeness obvious.
In case you performed a successful bisection, use the title of the change that
introduced the regression as the second part of your subject. Make the report
also mention the commit id of the culprit. In case of an unsuccessful bisection,
also mention the commit id of the culprit. In case of an unsuccessful bisection,
make your report mention the latest tested version that's working fine (say 5.7)
and the oldest where the issue occurs (say 5.8-rc1).

2
Documentation/admin-guide/sysctl/abi.rst
View File

@ -11,7 +11,7 @@ Documentation for /proc/sys/abi/
Copyright (c) 2020, Stephen Kitt
For general info, see :doc:`index`.
For general info, see Documentation/admin-guide/sysctl/index.rst.
------------------------------------------------------------------------------

44
Documentation/admin-guide/sysctl/kernel.rst
View File

@ -9,7 +9,8 @@ Copyright (c) 1998, 1999, Rik van Riel <riel@nl.linux.org>
Copyright (c) 2009, Shen Feng<shen@cn.fujitsu.com>
For general info and legal blurb, please look in :doc:`index`.
For general info and legal blurb, please look in
Documentation/admin-guide/sysctl/index.rst.
------------------------------------------------------------------------------
@ -54,7 +55,7 @@ free space valid for 30 seconds.
acpi_video_flags
================
See :doc:`/power/video`. This allows the video resume mode to be set,
See Documentation/power/video.rst. This allows the video resume mode to be set,
in a similar fashion to the ``acpi_sleep`` kernel parameter, by
combining the following values:
@ -89,7 +90,7 @@ is 0x15 and the full version number is 0x234, this file will contain
the value 340 = 0x154.
See the ``type_of_loader`` and ``ext_loader_type`` fields in
:doc:`/x86/boot` for additional information.
Documentation/x86/boot.rst for additional information.
bootloader_version (x86 only)
@ -99,7 +100,7 @@ The complete bootloader version number. In the example above, this
file will contain the value 564 = 0x234.
See the ``type_of_loader`` and ``ext_loader_ver`` fields in
:doc:`/x86/boot` for additional information.
Documentation/x86/boot.rst for additional information.
bpf_stats_enabled
@ -269,7 +270,7 @@ see the ``hostname(1)`` man page.
firmware_config
===============
See :doc:`/driver-api/firmware/fallback-mechanisms`.
See Documentation/driver-api/firmware/fallback-mechanisms.rst.
The entries in this directory allow the firmware loader helper
fallback to be controlled:
@ -297,7 +298,7 @@ crashes and outputting them to a serial console.
ftrace_enabled, stack_tracer_enabled
====================================
See :doc:`/trace/ftrace`.
See Documentation/trace/ftrace.rst.
hardlockup_all_cpu_backtrace
@ -325,7 +326,7 @@ when a hard lockup is detected.
1 Panic on hard lockup.
= ===========================
See :doc:`/admin-guide/lockup-watchdogs` for more information.
See Documentation/admin-guide/lockup-watchdogs.rst for more information.
This can also be set using the nmi_watchdog kernel parameter.
@ -333,7 +334,12 @@ hotplug
=======
Path for the hotplug policy agent.
Default value is "``/sbin/hotplug``".
Default value is ``CONFIG_UEVENT_HELPER_PATH``, which in turn defaults
to the empty string.
This file only exists when ``CONFIG_UEVENT_HELPER`` is enabled. Most
modern systems rely exclusively on the netlink-based uevent source and
don't need this.
hung_task_all_cpu_backtrace
@ -582,7 +588,8 @@ in a KVM virtual machine. This default can be overridden by adding::
nmi_watchdog=1
to the guest kernel command line (see :doc:`/admin-guide/kernel-parameters`).
to the guest kernel command line (see
Documentation/admin-guide/kernel-parameters.rst).
numa_balancing
@ -1067,7 +1074,7 @@ that support this feature.
real-root-dev
=============
See :doc:`/admin-guide/initrd`.
See Documentation/admin-guide/initrd.rst.
reboot-cmd (SPARC only)
@ -1161,7 +1168,7 @@ will take effect.
seccomp
=======
See :doc:`/userspace-api/seccomp_filter`.
See Documentation/userspace-api/seccomp_filter.rst.
sg-big-buff
@ -1332,7 +1339,7 @@ the boot PROM.
sysrq
=====
See :doc:`/admin-guide/sysrq`.
See Documentation/admin-guide/sysrq.rst.
tainted
@ -1362,15 +1369,16 @@ ORed together. The letters are seen in "Tainted" line of Oops reports.
131072 `(T)` The kernel was built with the struct randomization plugin
====== ===== ==============================================================
See :doc:`/admin-guide/tainted-kernels` for more information.
See Documentation/admin-guide/tainted-kernels.rst for more information.
Note:
writes to this sysctl interface will fail with ``EINVAL`` if the kernel is
booted with the command line option ``panic_on_taint=<bitmask>,nousertaint``
and any of the ORed together values being written to ``tainted`` match with
the bitmask declared on panic_on_taint.
See :doc:`/admin-guide/kernel-parameters` for more details on that particular
kernel command line option and its optional ``nousertaint`` switch.
See Documentation/admin-guide/kernel-parameters.rst for more details on
that particular kernel command line option and its optional
``nousertaint`` switch.
threads-max
===========
@ -1394,7 +1402,7 @@ If a value outside of this range is written to ``threads-max`` an
traceoff_on_warning
===================
When set, disables tracing (see :doc:`/trace/ftrace`) when a
When set, disables tracing (see Documentation/trace/ftrace.rst) when a
``WARN()`` is hit.
@ -1414,8 +1422,8 @@ will send them to printk() again.
This only works if the kernel was booted with ``tp_printk`` enabled.
See :doc:`/admin-guide/kernel-parameters` and
:doc:`/trace/boottime-trace`.
See Documentation/admin-guide/kernel-parameters.rst and
Documentation/trace/boottime-trace.rst.
.. _unaligned-dump-stack:

2
Documentation/arm/marvell.rst
View File

@ -259,7 +259,7 @@ Storage family
https://web.archive.org/web/20191129073953/http://www.marvell.com/storage/armada-sp/
Core:
Sheeva ARMv7 comatible Quad-core PJ4C
Sheeva ARMv7 compatible Quad-core PJ4C
(not supported in upstream Linux kernel)

2
Documentation/block/biodoc.rst
View File

@ -196,7 +196,7 @@ a virtual address mapping (unlike the earlier scheme of virtual address
do not have a corresponding kernel virtual address space mapping) and
low-memory pages.
Note: Please refer to :doc:`/core-api/dma-api-howto` for a discussion
Note: Please refer to Documentation/core-api/dma-api-howto.rst for a discussion
on PCI high mem DMA aspects and mapping of scatter gather lists, and support
for 64 bit PCI.

2
Documentation/block/blk-mq.rst
View File

@ -132,7 +132,7 @@ In order to indicate which request has been completed, every request is
identified by an integer, ranging from 0 to the dispatch queue size. This tag
is generated by the block layer and later reused by the device driver, removing
the need to create a redundant identifier. When a request is completed in the
drive, the tag is sent back to the block layer to notify it of the finalization.
driver, the tag is sent back to the block layer to notify it of the finalization.
This removes the need to do a linear search to find out which IO has been
completed.

2
Documentation/block/stat.rst
View File

@ -18,7 +18,7 @@ A.
each, it would be impossible to guarantee that a set of readings
represent a single point in time.
The stat file consists of a single line of text containing 11 decimal
The stat file consists of a single line of text containing 17 decimal
values separated by whitespace. The fields are summarized in the
following table, and described in more detail below.

13
Documentation/bpf/bpf_lsm.rst
View File

@ -20,10 +20,10 @@ LSM hook:
Other LSM hooks which can be instrumented can be found in
``include/linux/lsm_hooks.h``.
eBPF programs that use :doc:`/bpf/btf` do not need to include kernel headers
for accessing information from the attached eBPF program's context. They can
simply declare the structures in the eBPF program and only specify the fields
that need to be accessed.
eBPF programs that use Documentation/bpf/btf.rst do not need to include kernel
headers for accessing information from the attached eBPF program's context.
They can simply declare the structures in the eBPF program and only specify
the fields that need to be accessed.
.. code-block:: c
@ -88,8 +88,9 @@ example:
The ``__attribute__((preserve_access_index))`` is a clang feature that allows
the BPF verifier to update the offsets for the access at runtime using the
:doc:`/bpf/btf` information. Since the BPF verifier is aware of the types, it
also validates all the accesses made to the various types in the eBPF program.
Documentation/bpf/btf.rst information. Since the BPF verifier is aware of the
types, it also validates all the accesses made to the various types in the
eBPF program.
Loading
-------

24
Documentation/conf.py
View File

@ -41,15 +41,7 @@ extensions = ['kerneldoc', 'rstFlatTable', 'kernel_include',
'maintainers_include', 'sphinx.ext.autosectionlabel',
'kernel_abi', 'kernel_feat']
#
# cdomain is badly broken in Sphinx 3+. Leaving it out generates *most*
# of the docs correctly, but not all. Scream bloody murder but allow
# the process to proceed; hopefully somebody will fix this properly soon.
#
if major >= 3:
sys.stderr.write('''WARNING: The kernel documentation build process
support for Sphinx v3.0 and above is brand new. Be prepared for
possible issues in the generated output.\n''')
if (major > 3) or (minor > 0 or patch >= 2):
# Sphinx c function parser is more pedantic with regards to type
# checking. Due to that, having macros at c:function cause problems.
@ -353,6 +345,8 @@ latex_elements = {
# Additional stuff for the LaTeX preamble.
'preamble': '''
% Prevent column squeezing of tabulary.
\\setlength{\\tymin}{20em}
% Use some font with UTF-8 support with XeLaTeX
\\usepackage{fontspec}
\\setsansfont{DejaVu Sans}
@ -366,11 +360,23 @@ latex_elements = {
cjk_cmd = check_output(['fc-list', '--format="%{family[0]}\n"']).decode('utf-8', 'ignore')
if cjk_cmd.find("Noto Sans CJK SC") >= 0:
print ("enabling CJK for LaTeX builder")
latex_elements['preamble'] += '''
% This is needed for translations
\\usepackage{xeCJK}
\\setCJKmainfont{Noto Sans CJK SC}
% Define custom macros to on/off CJK
\\newcommand{\\kerneldocCJKon}{\\makexeCJKactive}
\\newcommand{\\kerneldocCJKoff}{\\makexeCJKinactive}
% To customize \sphinxtableofcontents
\\usepackage{etoolbox}
% Inactivate CJK after tableofcontents
\\apptocmd{\\sphinxtableofcontents}{\\kerneldocCJKoff}{}{}
'''
else:
latex_elements['preamble'] += '''
% Custom macros to on/off CJK (Dummy)
\\newcommand{\\kerneldocCJKon}{}
\\newcommand{\\kerneldocCJKoff}{}
'''
# Fix reference escape troubles with Sphinx 1.4.x

2
Documentation/core-api/bus-virt-phys-mapping.rst
View File

@ -8,7 +8,7 @@ How to access I/O mapped memory from within device drivers
The virt_to_bus() and bus_to_virt() functions have been
superseded by the functionality provided by the PCI DMA interface
(see :doc:`/core-api/dma-api-howto`). They continue
(see Documentation/core-api/dma-api-howto.rst). They continue
to be documented below for historical purposes, but new code
must not use them. --davidm 00/12/12

5
Documentation/core-api/dma-api.rst
View File

@ -5,7 +5,7 @@ Dynamic DMA mapping using the generic device
:Author: James E.J. Bottomley <James.Bottomley@HansenPartnership.com>
This document describes the DMA API. For a more gentle introduction
of the API (and actual examples), see :doc:`/core-api/dma-api-howto`.
of the API (and actual examples), see Documentation/core-api/dma-api-howto.rst.
This API is split into two pieces. Part I describes the basic API.
Part II describes extensions for supporting non-consistent memory
@ -479,7 +479,8 @@ without the _attrs suffixes, except that they pass an optional
dma_attrs.
The interpretation of DMA attributes is architecture-specific, and
each attribute should be documented in :doc:`/core-api/dma-attributes`.
each attribute should be documented in
Documentation/core-api/dma-attributes.rst.
If dma_attrs are 0, the semantics of each of these functions
is identical to those of the corresponding function

2
Documentation/core-api/dma-isa-lpc.rst
View File

@ -17,7 +17,7 @@ To do ISA style DMA you need to include two headers::
#include <asm/dma.h>
The first is the generic DMA API used to convert virtual addresses to
bus addresses (see :doc:`/core-api/dma-api` for details).
bus addresses (see Documentation/core-api/dma-api.rst for details).
The second contains the routines specific to ISA DMA transfers. Since
this is not present on all platforms make sure you construct your

4
Documentation/core-api/index.rst
View File

@ -48,7 +48,7 @@ Concurrency primitives
======================
How Linux keeps everything from happening at the same time. See
:doc:`/locking/index` for more related documentation.
Documentation/locking/index.rst for more related documentation.
.. toctree::
:maxdepth: 1
@ -77,7 +77,7 @@ Memory management
=================
How to allocate and use memory in the kernel. Note that there is a lot
more memory-management documentation in :doc:`/vm/index`.
more memory-management documentation in Documentation/vm/index.rst.
.. toctree::
:maxdepth: 1

9
Documentation/core-api/printk-formats.rst
View File

@ -37,14 +37,13 @@ Integer types
u64 %llu or %llx
If <type> is dependent on a config option for its size (e.g., sector_t,
blkcnt_t) or is architecture-dependent for its size (e.g., tcflag_t), use a
format specifier of its largest possible type and explicitly cast to it.
If <type> is architecture-dependent for its size (e.g., cycles_t, tcflag_t) or
is dependent on a config option for its size (e.g., blk_status_t), use a format
specifier of its largest possible type and explicitly cast to it.
Example::
printk("test: sector number/total blocks: %llu/%llu\n",
(unsigned long long)sector, (unsigned long long)blockcount);
printk("test: latency: %llu cycles\n", (unsigned long long)time);
Reminder: sizeof() returns type size_t.

509
Documentation/dev-tools/checkpatch.rst
View File

@ -246,6 +246,7 @@ Allocation style
The first argument for kcalloc or kmalloc_array should be the
number of elements. sizeof() as the first argument is generally
wrong.
See: https://www.kernel.org/doc/html/latest/core-api/memory-allocation.html
**ALLOC_SIZEOF_STRUCT**
@ -264,6 +265,7 @@ Allocation style
**ALLOC_WITH_MULTIPLY**
Prefer kmalloc_array/kcalloc over kmalloc/kzalloc with a
sizeof multiply.
See: https://www.kernel.org/doc/html/latest/core-api/memory-allocation.html
@ -284,6 +286,7 @@ API usage
BUG() or BUG_ON() should be avoided totally.
Use WARN() and WARN_ON() instead, and handle the "impossible"
error condition as gracefully as possible.
See: https://www.kernel.org/doc/html/latest/process/deprecated.html#bug-and-bug-on
**CONSIDER_KSTRTO**
@ -292,12 +295,161 @@ API usage
may lead to unexpected results in callers. The respective kstrtol(),
kstrtoll(), kstrtoul(), and kstrtoull() functions tend to be the
correct replacements.
See: https://www.kernel.org/doc/html/latest/process/deprecated.html#simple-strtol-simple-strtoll-simple-strtoul-simple-strtoull
**CONSTANT_CONVERSION**
Use of __constant_<foo> form is discouraged for the following functions::
__constant_cpu_to_be[x]
__constant_cpu_to_le[x]
__constant_be[x]_to_cpu
__constant_le[x]_to_cpu
__constant_htons
__constant_ntohs
Using any of these outside of include/uapi/ is not preferred as using the
function without __constant_ is identical when the argument is a
constant.
In big endian systems, the macros like __constant_cpu_to_be32(x) and
cpu_to_be32(x) expand to the same expression::
#define __constant_cpu_to_be32(x) ((__force __be32)(__u32)(x))
#define __cpu_to_be32(x) ((__force __be32)(__u32)(x))
In little endian systems, the macros __constant_cpu_to_be32(x) and
cpu_to_be32(x) expand to __constant_swab32 and __swab32. __swab32
has a __builtin_constant_p check::
#define __swab32(x) \
(__builtin_constant_p((__u32)(x)) ? \
___constant_swab32(x) : \
__fswab32(x))
So ultimately they have a special case for constants.
Similar is the case with all of the macros in the list. Thus
using the __constant_... forms are unnecessarily verbose and
not preferred outside of include/uapi.
See: https://lore.kernel.org/lkml/1400106425.12666.6.camel@joe-AO725/
**DEPRECATED_API**
Usage of a deprecated RCU API is detected. It is recommended to replace
old flavourful RCU APIs by their new vanilla-RCU counterparts.
The full list of available RCU APIs can be viewed from the kernel docs.
See: https://www.kernel.org/doc/html/latest/RCU/whatisRCU.html#full-list-of-rcu-apis
**DEPRECATED_VARIABLE**
EXTRA_{A,C,CPP,LD}FLAGS are deprecated and should be replaced by the new
flags added via commit f77bf01425b1 ("kbuild: introduce ccflags-y,
asflags-y and ldflags-y").
The following conversion scheme maybe used::
EXTRA_AFLAGS -> asflags-y
EXTRA_CFLAGS -> ccflags-y
EXTRA_CPPFLAGS -> cppflags-y
EXTRA_LDFLAGS -> ldflags-y
See:
1. https://lore.kernel.org/lkml/20070930191054.GA15876@uranus.ravnborg.org/
2. https://lore.kernel.org/lkml/1313384834-24433-12-git-send-email-lacombar@gmail.com/
3. https://www.kernel.org/doc/html/latest/kbuild/makefiles.html#compilation-flags
**DEVICE_ATTR_FUNCTIONS**
The function names used in DEVICE_ATTR is unusual.
Typically, the store and show functions are used with <attr>_store and
<attr>_show, where <attr> is a named attribute variable of the device.
Consider the following examples::
static DEVICE_ATTR(type, 0444, type_show, NULL);
static DEVICE_ATTR(power, 0644, power_show, power_store);
The function names should preferably follow the above pattern.
See: https://www.kernel.org/doc/html/latest/driver-api/driver-model/device.html#attributes
**DEVICE_ATTR_RO**
The DEVICE_ATTR_RO(name) helper macro can be used instead of
DEVICE_ATTR(name, 0444, name_show, NULL);
Note that the macro automatically appends _show to the named
attribute variable of the device for the show method.
See: https://www.kernel.org/doc/html/latest/driver-api/driver-model/device.html#attributes
**DEVICE_ATTR_RW**
The DEVICE_ATTR_RW(name) helper macro can be used instead of
DEVICE_ATTR(name, 0644, name_show, name_store);
Note that the macro automatically appends _show and _store to the
named attribute variable of the device for the show and store methods.
See: https://www.kernel.org/doc/html/latest/driver-api/driver-model/device.html#attributes
**DEVICE_ATTR_WO**
The DEVICE_AATR_WO(name) helper macro can be used instead of
DEVICE_ATTR(name, 0200, NULL, name_store);
Note that the macro automatically appends _store to the
named attribute variable of the device for the store method.
See: https://www.kernel.org/doc/html/latest/driver-api/driver-model/device.html#attributes
**DUPLICATED_SYSCTL_CONST**
Commit d91bff3011cf ("proc/sysctl: add shared variables for range
check") added some shared const variables to be used instead of a local
copy in each source file.
Consider replacing the sysctl range checking value with the shared
one in include/linux/sysctl.h. The following conversion scheme may
be used::
&zero -> SYSCTL_ZERO
&one -> SYSCTL_ONE
&int_max -> SYSCTL_INT_MAX
See:
1. https://lore.kernel.org/lkml/20190430180111.10688-1-mcroce@redhat.com/
2. https://lore.kernel.org/lkml/20190531131422.14970-1-mcroce@redhat.com/
**ENOSYS**
ENOSYS means that a nonexistent system call was called.
Earlier, it was wrongly used for things like invalid operations on
otherwise valid syscalls. This should be avoided in new code.
See: https://lore.kernel.org/lkml/5eb299021dec23c1a48fa7d9f2c8b794e967766d.1408730669.git.luto@amacapital.net/
**ENOTSUPP**
ENOTSUPP is not a standard error code and should be avoided in new patches.
EOPNOTSUPP should be used instead.
See: https://lore.kernel.org/netdev/20200510182252.GA411829@lunn.ch/
**EXPORT_SYMBOL**
EXPORT_SYMBOL should immediately follow the symbol to be exported.
**IN_ATOMIC**
in_atomic() is not for driver use so any such use is reported as an ERROR.
Also in_atomic() is often used to determine if sleeping is permitted,
but it is not reliable in this use model. Therefore its use is
strongly discouraged.
However, in_atomic() is ok for core kernel use.
See: https://lore.kernel.org/lkml/20080320201723.b87b3732.akpm@linux-foundation.org/
**LOCKDEP**
The lockdep_no_validate class was added as a temporary measure to
prevent warnings on conversion of device->sem to device->mutex.
It should not be used for any other purpose.
See: https://lore.kernel.org/lkml/1268959062.9440.467.camel@laptop/
**MALFORMED_INCLUDE**
@ -308,14 +460,21 @@ API usage
**USE_LOCKDEP**
lockdep_assert_held() annotations should be preferred over
assertions based on spin_is_locked()
See: https://www.kernel.org/doc/html/latest/locking/lockdep-design.html#annotations
**UAPI_INCLUDE**
No #include statements in include/uapi should use a uapi/ path.
**USLEEP_RANGE**
usleep_range() should be preferred over udelay(). The proper way of
using usleep_range() is mentioned in the kernel docs.
Comment style
-------------
See: https://www.kernel.org/doc/html/latest/timers/timers-howto.html#delays-information-on-the-various-kernel-delay-sleep-mechanisms
Comments
--------
**BLOCK_COMMENT_STYLE**
The comment style is incorrect. The preferred style for multi-
@ -338,8 +497,24 @@ Comment style
**C99_COMMENTS**
C99 style single line comments (//) should not be used.
Prefer the block comment style instead.
See: https://www.kernel.org/doc/html/latest/process/coding-style.html#commenting
**DATA_RACE**
Applications of data_race() should have a comment so as to document the
reasoning behind why it was deemed safe.
See: https://lore.kernel.org/lkml/20200401101714.44781-1-elver@google.com/
**FSF_MAILING_ADDRESS**
Kernel maintainers reject new instances of the GPL boilerplate paragraph
directing people to write to the FSF for a copy of the GPL, since the
FSF has moved in the past and may do so again.
So do not write paragraphs about writing to the Free Software Foundation's
mailing address.
See: https://lore.kernel.org/lkml/20131006222342.GT19510@leaf/
Commit message
--------------
@ -347,6 +522,7 @@ Commit message
**BAD_SIGN_OFF**
The signed-off-by line does not fall in line with the standards
specified by the community.
See: https://www.kernel.org/doc/html/latest/process/submitting-patches.html#developer-s-certificate-of-origin-1-1
**BAD_STABLE_ADDRESS_STYLE**
@ -368,12 +544,33 @@ Commit message
**COMMIT_MESSAGE**
The patch is missing a commit description. A brief
description of the changes made by the patch should be added.
See: https://www.kernel.org/doc/html/latest/process/submitting-patches.html#describe-your-changes
**EMAIL_SUBJECT**
Naming the tool that found the issue is not very useful in the
subject line. A good subject line summarizes the change that
the patch brings.
See: https://www.kernel.org/doc/html/latest/process/submitting-patches.html#describe-your-changes
**FROM_SIGN_OFF_MISMATCH**
The author's email does not match with that in the Signed-off-by:
line(s). This can be sometimes caused due to an improperly configured
email client.
This message is emitted due to any of the following reasons::
- The email names do not match.
- The email addresses do not match.
- The email subaddresses do not match.
- The email comments do not match.
**MISSING_SIGN_OFF**
The patch is missing a Signed-off-by line. A signed-off-by
line should be added according to Developer's certificate of
Origin.
See: https://www.kernel.org/doc/html/latest/process/submitting-patches.html#sign-your-work-the-developer-s-certificate-of-origin
**NO_AUTHOR_SIGN_OFF**
@ -382,6 +579,7 @@ Commit message
end of explanation of the patch to denote that the author has
written it or otherwise has the rights to pass it on as an open
source patch.
See: https://www.kernel.org/doc/html/latest/process/submitting-patches.html#sign-your-work-the-developer-s-certificate-of-origin
**DIFF_IN_COMMIT_MSG**
@ -389,6 +587,7 @@ Commit message
This causes problems when one tries to apply a file containing both
the changelog and the diff because patch(1) tries to apply the diff
which it found in the changelog.
See: https://lore.kernel.org/lkml/20150611134006.9df79a893e3636019ad2759e@linux-foundation.org/
**GERRIT_CHANGE_ID**
@ -431,6 +630,7 @@ Comparison style
**BOOL_COMPARISON**
Comparisons of A to true and false are better written
as A and !A.
See: https://lore.kernel.org/lkml/1365563834.27174.12.camel@joe-AO722/
**COMPARISON_TO_NULL**
@ -442,6 +642,87 @@ Comparison style
side of the test should be avoided.
Indentation and Line Breaks
---------------------------
**CODE_INDENT**
Code indent should use tabs instead of spaces.
Outside of comments, documentation and Kconfig,
spaces are never used for indentation.
See: https://www.kernel.org/doc/html/latest/process/coding-style.html#indentation
**DEEP_INDENTATION**
Indentation with 6 or more tabs usually indicate overly indented
code.
It is suggested to refactor excessive indentation of
if/else/for/do/while/switch statements.
See: https://lore.kernel.org/lkml/1328311239.21255.24.camel@joe2Laptop/
**SWITCH_CASE_INDENT_LEVEL**
switch should be at the same indent as case.
Example::
switch (suffix) {
case 'G':
case 'g':
mem <<= 30;
break;
case 'M':
case 'm':
mem <<= 20;
break;
case 'K':
case 'k':
mem <<= 10;
fallthrough;
default:
break;
}
See: https://www.kernel.org/doc/html/latest/process/coding-style.html#indentation
**LONG_LINE**
The line has exceeded the specified maximum length.
To use a different maximum line length, the --max-line-length=n option
may be added while invoking checkpatch.
Earlier, the default line length was 80 columns. Commit bdc48fa11e46
("checkpatch/coding-style: deprecate 80-column warning") increased the
limit to 100 columns. This is not a hard limit either and it's
preferable to stay within 80 columns whenever possible.
See: https://www.kernel.org/doc/html/latest/process/coding-style.html#breaking-long-lines-and-strings
**LONG_LINE_STRING**
A string starts before but extends beyond the maximum line length.
To use a different maximum line length, the --max-line-length=n option
may be added while invoking checkpatch.
See: https://www.kernel.org/doc/html/latest/process/coding-style.html#breaking-long-lines-and-strings
**LONG_LINE_COMMENT**
A comment starts before but extends beyond the maximum line length.
To use a different maximum line length, the --max-line-length=n option
may be added while invoking checkpatch.
See: https://www.kernel.org/doc/html/latest/process/coding-style.html#breaking-long-lines-and-strings
**TRAILING_STATEMENTS**
Trailing statements (for example after any conditional) should be
on the next line.
Statements, such as::
if (x == y) break;
should be::
if (x == y)
break;
Macros, Attributes and Symbols
------------------------------
@ -472,7 +753,7 @@ Macros, Attributes and Symbols
**BIT_MACRO**
Defines like: 1 << <digit> could be BIT(digit).
The BIT() macro is defined in include/linux/bitops.h::
The BIT() macro is defined via include/linux/bits.h::
#define BIT(nr) (1UL << (nr))
@ -492,6 +773,7 @@ Macros, Attributes and Symbols
The kernel does *not* use the ``__DATE__`` and ``__TIME__`` macros,
and enables warnings if they are used as they can lead to
non-deterministic builds.
See: https://www.kernel.org/doc/html/latest/kbuild/reproducible-builds.html#timestamps
**DEFINE_ARCH_HAS**
@ -502,8 +784,12 @@ Macros, Attributes and Symbols
want architectures able to override them with optimized ones, we
should either use weak functions (appropriate for some cases), or
the symbol that protects them should be the same symbol we use.
See: https://lore.kernel.org/lkml/CA+55aFycQ9XJvEOsiM3txHL5bjUc8CeKWJNR_H+MiicaddB42Q@mail.gmail.com/
**DO_WHILE_MACRO_WITH_TRAILING_SEMICOLON**
do {} while(0) macros should not have a trailing semicolon.
**INIT_ATTRIBUTE**
Const init definitions should use __initconst instead of
__initdata.
@ -528,6 +814,20 @@ Macros, Attributes and Symbols
...
}
**MISPLACED_INIT**
It is possible to use section markers on variables in a way
which gcc doesn't understand (or at least not the way the
developer intended)::
static struct __initdata samsung_pll_clock exynos4_plls[nr_plls] = {
does not put exynos4_plls in the .initdata section. The __initdata
marker can be virtually anywhere on the line, except right after
"struct". The preferred location is before the "=" sign if there is
one, or before the trailing ";" otherwise.
See: https://lore.kernel.org/lkml/1377655732.3619.19.camel@joe-AO722/
**MULTISTATEMENT_MACRO_USE_DO_WHILE**
Macros with multiple statements should be enclosed in a
do - while block. Same should also be the case for macros
@ -541,6 +841,10 @@ Macros, Attributes and Symbols
See: https://www.kernel.org/doc/html/latest/process/coding-style.html#macros-enums-and-rtl
**PREFER_FALLTHROUGH**
Use the `fallthrough;` pseudo keyword instead of
`/* fallthrough */` like comments.
**WEAK_DECLARATION**
Using weak declarations like __attribute__((weak)) or __weak
can have unintended link defects. Avoid using them.
@ -551,8 +855,51 @@ Functions and Variables
**CAMELCASE**
Avoid CamelCase Identifiers.
See: https://www.kernel.org/doc/html/latest/process/coding-style.html#naming
**CONST_CONST**
Using `const <type> const *` is generally meant to be
written `const <type> * const`.
**CONST_STRUCT**
Using const is generally a good idea. Checkpatch reads
a list of frequently used structs that are always or
almost always constant.
The existing structs list can be viewed from
`scripts/const_structs.checkpatch`.
See: https://lore.kernel.org/lkml/alpine.DEB.2.10.1608281509480.3321@hadrien/
**EMBEDDED_FUNCTION_NAME**
Embedded function names are less appropriate to use as
refactoring can cause function renaming. Prefer the use of
"%s", __func__ to embedded function names.
Note that this does not work with -f (--file) checkpatch option
as it depends on patch context providing the function name.
**FUNCTION_ARGUMENTS**
This warning is emitted due to any of the following reasons:
1. Arguments for the function declaration do not follow
the identifier name. Example::
void foo
(int bar, int baz)
This should be corrected to::
void foo(int bar, int baz)
2. Some arguments for the function definition do not
have an identifier name. Example::
void foo(int)
All arguments should have identifier names.
**FUNCTION_WITHOUT_ARGS**
Function declarations without arguments like::
@ -583,6 +930,34 @@ Functions and Variables
return bar;
Permissions
-----------
**DEVICE_ATTR_PERMS**
The permissions used in DEVICE_ATTR are unusual.
Typically only three permissions are used - 0644 (RW), 0444 (RO)
and 0200 (WO).
See: https://www.kernel.org/doc/html/latest/filesystems/sysfs.html#attributes
**EXECUTE_PERMISSIONS**
There is no reason for source files to be executable. The executable
bit can be removed safely.
**EXPORTED_WORLD_WRITABLE**
Exporting world writable sysfs/debugfs files is usually a bad thing.
When done arbitrarily they can introduce serious security bugs.
In the past, some of the debugfs vulnerabilities would seemingly allow
any local user to write arbitrary values into device registers - a
situation from which little good can be expected to emerge.
See: https://lore.kernel.org/linux-arm-kernel/cover.1296818921.git.segoon@openwall.com/
**NON_OCTAL_PERMISSIONS**
Permission bits should use 4 digit octal permissions (like 0700 or 0444).
Avoid using any other base like decimal.
Spacing and Brackets
--------------------
@ -616,7 +991,7 @@ Spacing and Brackets
1. With a type on the left::
;int [] a;
int [] a;
2. At the beginning of a line for slice initialisers::
@ -626,12 +1001,6 @@ Spacing and Brackets
= { [0...10] = 5 }
**CODE_INDENT**
Code indent should use tabs instead of spaces.
Outside of comments, documentation and Kconfig,
spaces are never used for indentation.
See: https://www.kernel.org/doc/html/latest/process/coding-style.html#indentation
**CONCATENATED_STRING**
Concatenated elements should have a space in between.
Example::
@ -644,17 +1013,20 @@ Spacing and Brackets
**ELSE_AFTER_BRACE**
`else {` should follow the closing block `}` on the same line.
See: https://www.kernel.org/doc/html/latest/process/coding-style.html#placing-braces-and-spaces
**LINE_SPACING**
Vertical space is wasted given the limited number of lines an
editor window can display when multiple blank lines are used.
See: https://www.kernel.org/doc/html/latest/process/coding-style.html#spaces
**OPEN_BRACE**
The opening brace should be following the function definitions on the
next line. For any non-functional block it should be on the same line
as the last construct.
See: https://www.kernel.org/doc/html/latest/process/coding-style.html#placing-braces-and-spaces
**POINTER_LOCATION**
@ -671,37 +1043,47 @@ Spacing and Brackets
**SPACING**
Whitespace style used in the kernel sources is described in kernel docs.
See: https://www.kernel.org/doc/html/latest/process/coding-style.html#spaces
**SWITCH_CASE_INDENT_LEVEL**
switch should be at the same indent as case.
Example::
switch (suffix) {
case 'G':
case 'g':
mem <<= 30;
break;
case 'M':
case 'm':
mem <<= 20;
break;
case 'K':
case 'k':
mem <<= 10;
/* fall through */
default:
break;
}
See: https://www.kernel.org/doc/html/latest/process/coding-style.html#indentation
**TRAILING_WHITESPACE**
Trailing whitespace should always be removed.
Some editors highlight the trailing whitespace and cause visual
distractions when editing files.
See: https://www.kernel.org/doc/html/latest/process/coding-style.html#spaces
**UNNECESSARY_PARENTHESES**
Parentheses are not required in the following cases:
1. Function pointer uses::
(foo->bar)();
could be::
foo->bar();
2. Comparisons in if::
if ((foo->bar) && (foo->baz))
if ((foo == bar))
could be::
if (foo->bar && foo->baz)
if (foo == bar)
3. addressof/dereference single Lvalues::
&(foo->bar)
*(foo->bar)
could be::
&foo->bar
*foo->bar
**WHILE_AFTER_BRACE**
while should follow the closing bracket on the same line::
@ -723,17 +1105,50 @@ Others
The patch seems to be corrupted or lines are wrapped.
Please regenerate the patch file before sending it to the maintainer.
**CVS_KEYWORD**
Since linux moved to git, the CVS markers are no longer used.
So, CVS style keywords ($Id$, $Revision$, $Log$) should not be
added.
**DEFAULT_NO_BREAK**
switch default case is sometimes written as "default:;". This can
cause new cases added below default to be defective.
A "break;" should be added after empty default statement to avoid
unwanted fallthrough.
**DOS_LINE_ENDINGS**
For DOS-formatted patches, there are extra ^M symbols at the end of
the line. These should be removed.
**EXECUTE_PERMISSIONS**
There is no reason for source files to be executable. The executable
bit can be removed safely.
**DT_SCHEMA_BINDING_PATCH**
DT bindings moved to a json-schema based format instead of
freeform text.
**NON_OCTAL_PERMISSIONS**
Permission bits should use 4 digit octal permissions (like 0700 or 0444).
Avoid using any other base like decimal.
See: https://www.kernel.org/doc/html/latest/devicetree/bindings/writing-schema.html
**DT_SPLIT_BINDING_PATCH**
Devicetree bindings should be their own patch. This is because
bindings are logically independent from a driver implementation,
they have a different maintainer (even though they often
are applied via the same tree), and it makes for a cleaner history in the
DT only tree created with git-filter-branch.
See: https://www.kernel.org/doc/html/latest/devicetree/bindings/submitting-patches.html#i-for-patch-submitters
**EMBEDDED_FILENAME**
Embedding the complete filename path inside the file isn't particularly
useful as often the path is moved around and becomes incorrect.
**FILE_PATH_CHANGES**
Whenever files are added, moved, or deleted, the MAINTAINERS file
patterns can be out of sync or outdated.
So MAINTAINERS might need updating in these cases.
**MEMSET**
The memset use appears to be incorrect. This may be caused due to
badly ordered parameters. Please recheck the usage.
**NOT_UNIFIED_DIFF**
The patch file does not appear to be in unified-diff format. Please
@ -742,14 +1157,12 @@ Others
**PRINTF_0XDECIMAL**
Prefixing 0x with decimal output is defective and should be corrected.
**TRAILING_STATEMENTS**
Trailing statements (for example after any conditional) should be
on the next line.
Like::
**SPDX_LICENSE_TAG**
The source file is missing or has an improper SPDX identifier tag.
The Linux kernel requires the precise SPDX identifier in all source files,
and it is thoroughly documented in the kernel docs.
if (x == y) break;
See: https://www.kernel.org/doc/html/latest/process/license-rules.html
should be::
if (x == y)
break;
**TYPO_SPELLING**
Some words may have been misspelled. Consider reviewing them.

8
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@ -10,7 +10,7 @@ API Reference
This section documents the KUnit kernel testing API. It is divided into the
following sections:
================================= ==============================================
:doc:`test` documents all of the standard testing API
excluding mocking or mocking related features.
================================= ==============================================
Documentation/dev-tools/kunit/api/test.rst
- documents all of the standard testing API excluding mocking
or mocking related features.

2
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@ -97,7 +97,7 @@ things to try.
modules will automatically execute associated tests when loaded. Test results
can be collected from ``/sys/kernel/debug/kunit/<test suite>/results``, and
can be parsed with ``kunit.py parse``. For more details, see "KUnit on
non-UML architectures" in :doc:`usage`.
non-UML architectures" in Documentation/dev-tools/kunit/usage.rst.
If none of the above tricks help, you are always welcome to email any issues to
kunit-dev@googlegroups.com.

14
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@ -36,7 +36,7 @@ To make running these tests (and reading the results) easier, KUnit offers
results. This provides a quick way of running KUnit tests during development,
without requiring a virtual machine or separate hardware.
Get started now: :doc:`start`
Get started now: Documentation/dev-tools/kunit/start.rst
Why KUnit?
==========
@ -88,9 +88,9 @@ it takes to read their test log?
How do I use it?
================
* :doc:`start` - for new users of KUnit
* :doc:`tips` - for short examples of best practices
* :doc:`usage` - for a more detailed explanation of KUnit features
* :doc:`api/index` - for the list of KUnit APIs used for testing
* :doc:`kunit-tool` - for more information on the kunit_tool helper script
* :doc:`faq` - for answers to some common questions about KUnit
* Documentation/dev-tools/kunit/start.rst - for new users of KUnit
* Documentation/dev-tools/kunit/tips.rst - for short examples of best practices
* Documentation/dev-tools/kunit/usage.rst - for a more detailed explanation of KUnit features
* Documentation/dev-tools/kunit/api/index.rst - for the list of KUnit APIs used for testing
* Documentation/dev-tools/kunit/kunit-tool.rst - for more information on the kunit_tool helper script
* Documentation/dev-tools/kunit/faq.rst - for answers to some common questions about KUnit

4
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View File

@ -21,7 +21,7 @@ The wrapper can be run with:
./tools/testing/kunit/kunit.py run
For more information on this wrapper (also called kunit_tool) check out the
:doc:`kunit-tool` page.
Documentation/dev-tools/kunit/kunit-tool.rst page.
Creating a .kunitconfig
-----------------------
@ -234,7 +234,7 @@ Congrats! You just wrote your first KUnit test!
Next Steps
==========
* Check out the :doc:`tips` page for tips on
* Check out the Documentation/dev-tools/kunit/tips.rst page for tips on
writing idiomatic KUnit tests.
* Optional: see the :doc:`usage` page for a more
in-depth explanation of KUnit.

5
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@ -125,7 +125,8 @@ Here's a slightly in-depth example of how one could implement "mocking":
Note: here we're able to get away with using ``test->priv``, but if you wanted
something more flexible you could use a named ``kunit_resource``, see :doc:`api/test`.
something more flexible you could use a named ``kunit_resource``, see
Documentation/dev-tools/kunit/api/test.rst.
Failing the current test
------------------------
@ -185,5 +186,5 @@ Alternatively, one can take full control over the error message by using ``KUNIT
Next Steps
==========
* Optional: see the :doc:`usage` page for a more
* Optional: see the Documentation/dev-tools/kunit/usage.rst page for a more
in-depth explanation of KUnit.

8
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@ -10,7 +10,7 @@ understand it. This guide assumes a working knowledge of the Linux kernel and
some basic knowledge of testing.
For a high level introduction to KUnit, including setting up KUnit for your
project, see :doc:`start`.
project, see Documentation/dev-tools/kunit/start.rst.
Organization of this document
=============================
@ -99,7 +99,8 @@ violated; however, the test will continue running, potentially trying other
expectations until the test case ends or is otherwise terminated. This is as
opposed to *assertions* which are discussed later.
To learn about more expectations supported by KUnit, see :doc:`api/test`.
To learn about more expectations supported by KUnit, see
Documentation/dev-tools/kunit/api/test.rst.
.. note::
A single test case should be pretty short, pretty easy to understand,
@ -216,7 +217,8 @@ test suite in a special linker section so that it can be run by KUnit either
after late_init, or when the test module is loaded (depending on whether the
test was built in or not).
For more information on these types of things see the :doc:`api/test`.
For more information on these types of things see the
Documentation/dev-tools/kunit/api/test.rst.
Common Patterns
===============

16
Documentation/dev-tools/testing-overview.rst
View File

@ -71,15 +71,15 @@ can be used to verify that a test is executing particular functions or lines
of code. This is useful for determining how much of the kernel is being tested,
and for finding corner-cases which are not covered by the appropriate test.
:doc:`gcov` is GCC's coverage testing tool, which can be used with the kernel
to get global or per-module coverage. Unlike KCOV, it does not record per-task
coverage. Coverage data can be read from debugfs, and interpreted using the
usual gcov tooling.
Documentation/dev-tools/gcov.rst is GCC's coverage testing tool, which can be
used with the kernel to get global or per-module coverage. Unlike KCOV, it
does not record per-task coverage. Coverage data can be read from debugfs,
and interpreted using the usual gcov tooling.
:doc:`kcov` is a feature which can be built in to the kernel to allow
capturing coverage on a per-task level. It's therefore useful for fuzzing and
other situations where information about code executed during, for example, a
single syscall is useful.
Documentation/dev-tools/kcov.rst is a feature which can be built in to the
kernel to allow capturing coverage on a per-task level. It's therefore useful
for fuzzing and other situations where information about code executed during,
for example, a single syscall is useful.
Dynamic Analysis Tools

11
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@ -7,8 +7,8 @@ Submitting Devicetree (DT) binding patches
I. For patch submitters
=======================
0) Normal patch submission rules from Documentation/process/submitting-patches.rst
applies.
0) Normal patch submission rules from
Documentation/process/submitting-patches.rst applies.
1) The Documentation/ and include/dt-bindings/ portion of the patch should
be a separate patch. The preferred subject prefix for binding patches is::
@ -25,8 +25,8 @@ I. For patch submitters
make dt_binding_check
See Documentation/devicetree/bindings/writing-schema.rst for more details about
schema and tools setup.
See Documentation/devicetree/bindings/writing-schema.rst for more details
about schema and tools setup.
3) DT binding files should be dual licensed. The preferred license tag is
(GPL-2.0-only OR BSD-2-Clause).
@ -84,7 +84,8 @@ II. For kernel maintainers
III. Notes
==========
0) Please see :doc:`ABI` for details regarding devicetree ABI.
0) Please see Documentation/devicetree/bindings/ABI.rst for details
regarding devicetree ABI.
1) This document is intended as a general familiarization with the process as
decided at the 2013 Kernel Summit. When in doubt, the current word of the

8
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@ -237,10 +237,10 @@ We have been trying to improve the situation through the creation of
a set of "books" that group documentation for specific readers. These
include:
- :doc:`../admin-guide/index`
- :doc:`../core-api/index`
- :doc:`../driver-api/index`
- :doc:`../userspace-api/index`
- Documentation/admin-guide/index.rst
- Documentation/core-api/index.rst
- Documentation/driver-api/index.rst
- Documentation/userspace-api/index.rst
As well as this book on documentation itself.

2
Documentation/driver-api/acpi/linuxized-acpica.rst
View File

@ -276,4 +276,4 @@ before they become available from the ACPICA release process.
# git clone https://github.com/acpica/acpica
# git clone https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
# cd acpica
# generate/linux/divergences.sh -s ../linux
# generate/linux/divergence.sh -s ../linux

4
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View File

@ -9,13 +9,13 @@ with them.
For examples of already existing generic drivers that will also be good
examples for any other kernel drivers you want to author, refer to
:doc:`drivers-on-gpio`
Documentation/driver-api/gpio/drivers-on-gpio.rst
For any kind of mass produced system you want to support, such as servers,
laptops, phones, tablets, routers, and any consumer or office or business goods
using appropriate kernel drivers is paramount. Submit your code for inclusion
in the upstream Linux kernel when you feel it is mature enough and you will get
help to refine it, see :doc:`../../process/submitting-patches`.
help to refine it, see Documentation/process/submitting-patches.rst.
In Linux GPIO lines also have a userspace ABI.

10
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@ -25,16 +25,16 @@ ioctl commands that follow modern conventions: ``_IO``, ``_IOR``,
with the correct parameters:
_IO/_IOR/_IOW/_IOWR
The macro name specifies how the argument will be used.  It may be a
The macro name specifies how the argument will be used. It may be a
pointer to data to be passed into the kernel (_IOW), out of the kernel
(_IOR), or both (_IOWR).  _IO can indicate either commands with no
(_IOR), or both (_IOWR). _IO can indicate either commands with no
argument or those passing an integer value instead of a pointer.
It is recommended to only use _IO for commands without arguments,
and use pointers for passing data.
type
An 8-bit number, often a character literal, specific to a subsystem
or driver, and listed in :doc:`../userspace-api/ioctl/ioctl-number`
or driver, and listed in Documentation/userspace-api/ioctl/ioctl-number.rst
nr
An 8-bit number identifying the specific command, unique for a give
@ -200,10 +200,10 @@ cause an information leak, which can be used to defeat kernel address
space layout randomization (KASLR), helping in an attack.
For this reason (and for compat support) it is best to avoid any
implicit padding in data structures.  Where there is implicit padding
implicit padding in data structures. Where there is implicit padding
in an existing structure, kernel drivers must be careful to fully
initialize an instance of the structure before copying it to user
space.  This is usually done by calling memset() before assigning to
space. This is usually done by calling memset() before assigning to
individual members.
Subsystem abstractions

8
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@ -217,7 +217,7 @@ system-wide transition to a sleep state even though its :c:member:`runtime_auto`
flag is clear.
For more information about the runtime power management framework, refer to
:file:`Documentation/power/runtime_pm.rst`.
Documentation/power/runtime_pm.rst.
Calling Drivers to Enter and Leave System Sleep States
@ -655,7 +655,7 @@ been thawed. Generally speaking, the PM notifiers are suitable for performing
actions that either require user space to be available, or at least won't
interfere with user space.
For details refer to :doc:`notifiers`.
For details refer to Documentation/driver-api/pm/notifiers.rst.
Device Low-Power (suspend) States
@ -726,7 +726,7 @@ it into account in any way.
Devices may be defined as IRQ-safe which indicates to the PM core that their
runtime PM callbacks may be invoked with disabled interrupts (see
:file:`Documentation/power/runtime_pm.rst` for more information). If an
Documentation/power/runtime_pm.rst for more information). If an
IRQ-safe device belongs to a PM domain, the runtime PM of the domain will be
disallowed, unless the domain itself is defined as IRQ-safe. However, it
makes sense to define a PM domain as IRQ-safe only if all the devices in it
@ -805,7 +805,7 @@ The ``DPM_FLAG_MAY_SKIP_RESUME`` Driver Flag
--------------------------------------------
During system-wide resume from a sleep state it's easiest to put devices into
the full-power state, as explained in :file:`Documentation/power/runtime_pm.rst`.
the full-power state, as explained in Documentation/power/runtime_pm.rst.
[Refer to that document for more information regarding this particular issue as
well as for information on the device runtime power management framework in
general.] However, it often is desirable to leave devices in suspend after

3
Documentation/driver-api/surface_aggregator/clients/index.rst
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@ -5,7 +5,8 @@ Client Driver Documentation
===========================
This is the documentation for client drivers themselves. Refer to
:doc:`../client` for documentation on how to write client drivers.
Documentation/driver-api/surface_aggregator/client.rst for documentation
on how to write client drivers.
.. toctree::
:maxdepth: 1

15
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@ -87,10 +87,11 @@ native SSAM devices, i.e. devices that are not defined in ACPI and not
implemented as platform devices, via |ssam_device| and |ssam_device_driver|
simplify management of client devices and client drivers.
Refer to :doc:`client` for documentation regarding the client device/driver
API and interface options for other kernel drivers. It is recommended to
familiarize oneself with that chapter and the :doc:`ssh` before continuing
with the architectural overview below.
Refer to Documentation/driver-api/surface_aggregator/client.rst for
documentation regarding the client device/driver API and interface options
for other kernel drivers. It is recommended to familiarize oneself with
that chapter and the Documentation/driver-api/surface_aggregator/ssh.rst
before continuing with the architectural overview below.
Packet Transport Layer
@ -190,9 +191,9 @@ with success on the transmitter thread.
Transmission of sequenced packets is limited by the number of concurrently
pending packets, i.e. a limit on how many packets may be waiting for an ACK
from the EC in parallel. This limit is currently set to one (see :doc:`ssh`
for the reasoning behind this). Control packets (i.e. ACK and NAK) can
always be transmitted.
from the EC in parallel. This limit is currently set to one (see
Documentation/driver-api/surface_aggregator/ssh.rst for the reasoning behind
this). Control packets (i.e. ACK and NAK) can always be transmitted.
Receiver Thread
---------------

6
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@ -73,5 +73,7 @@ being a direct response to a previous request. We may also refer to requests
without response as commands. In general, events need to be enabled via one
of multiple dedicated requests before they are sent by the EC.
See :doc:`ssh` for a more technical protocol documentation and
:doc:`internal` for an overview of the internal driver architecture.
See Documentation/driver-api/surface_aggregator/ssh.rst for a
more technical protocol documentation and
Documentation/driver-api/surface_aggregator/internal.rst for an
overview of the internal driver architecture.

6
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@ -10,7 +10,7 @@ API overview
The big picture is that USB drivers can continue to ignore most DMA issues,
though they still must provide DMA-ready buffers (see
:doc:`/core-api/dma-api-howto`). That's how they've worked through
Documentation/core-api/dma-api-howto.rst). That's how they've worked through
the 2.4 (and earlier) kernels, or they can now be DMA-aware.
DMA-aware usb drivers:
@ -60,7 +60,7 @@ and effects like cache-trashing can impose subtle penalties.
force a consistent memory access ordering by using memory barriers. It's
not using a streaming DMA mapping, so it's good for small transfers on
systems where the I/O would otherwise thrash an IOMMU mapping. (See
:doc:`/core-api/dma-api-howto` for definitions of "coherent" and
Documentation/core-api/dma-api-howto.rst for definitions of "coherent" and
"streaming" DMA mappings.)
Asking for 1/Nth of a page (as well as asking for N pages) is reasonably
@ -91,7 +91,7 @@ Working with existing buffers
Existing buffers aren't usable for DMA without first being mapped into the
DMA address space of the device. However, most buffers passed to your
driver can safely be used with such DMA mapping. (See the first section
of :doc:`/core-api/dma-api-howto`, titled "What memory is DMA-able?")
of Documentation/core-api/dma-api-howto.rst, titled "What memory is DMA-able?")
- When you're using scatterlists, you can map everything at once. On some
systems, this kicks in an IOMMU and turns the scatterlists into single

24
Documentation/fault-injection/fault-injection.rst
View File

@ -78,8 +78,10 @@ configuration of fault-injection capabilities.
- /sys/kernel/debug/fail*/times:
specifies how many times failures may happen at most.
A value of -1 means "no limit".
specifies how many times failures may happen at most. A value of -1
means "no limit". Note, though, that this file only accepts unsigned
values. So, if you want to specify -1, you better use 'printf' instead
of 'echo', e.g.: $ printf %#x -1 > times
- /sys/kernel/debug/fail*/space:
@ -167,11 +169,13 @@ configuration of fault-injection capabilities.
- ERRNO: retval must be -1 to -MAX_ERRNO (-4096).
- ERR_NULL: retval must be 0 or -1 to -MAX_ERRNO (-4096).
- /sys/kernel/debug/fail_function/<functiuon-name>/retval:
- /sys/kernel/debug/fail_function/<function-name>/retval:
specifies the "error" return value to inject to the given
function for given function. This will be created when
user specifies new injection entry.
specifies the "error" return value to inject to the given function.
This will be created when the user specifies a new injection entry.
Note that this file only accepts unsigned values. So, if you want to
use a negative errno, you better use 'printf' instead of 'echo', e.g.:
$ printf %#x -12 > retval
Boot option
^^^^^^^^^^^
@ -255,7 +259,7 @@ Application Examples
echo Y > /sys/kernel/debug/$FAILTYPE/task-filter
echo 10 > /sys/kernel/debug/$FAILTYPE/probability
echo 100 > /sys/kernel/debug/$FAILTYPE/interval
echo -1 > /sys/kernel/debug/$FAILTYPE/times
printf %#x -1 > /sys/kernel/debug/$FAILTYPE/times
echo 0 > /sys/kernel/debug/$FAILTYPE/space
echo 2 > /sys/kernel/debug/$FAILTYPE/verbose
echo 1 > /sys/kernel/debug/$FAILTYPE/ignore-gfp-wait
@ -309,7 +313,7 @@ Application Examples
echo N > /sys/kernel/debug/$FAILTYPE/task-filter
echo 10 > /sys/kernel/debug/$FAILTYPE/probability
echo 100 > /sys/kernel/debug/$FAILTYPE/interval
echo -1 > /sys/kernel/debug/$FAILTYPE/times
printf %#x -1 > /sys/kernel/debug/$FAILTYPE/times
echo 0 > /sys/kernel/debug/$FAILTYPE/space
echo 2 > /sys/kernel/debug/$FAILTYPE/verbose
echo 1 > /sys/kernel/debug/$FAILTYPE/ignore-gfp-wait
@ -336,11 +340,11 @@ Application Examples
FAILTYPE=fail_function
FAILFUNC=open_ctree
echo $FAILFUNC > /sys/kernel/debug/$FAILTYPE/inject
echo -12 > /sys/kernel/debug/$FAILTYPE/$FAILFUNC/retval
printf %#x -12 > /sys/kernel/debug/$FAILTYPE/$FAILFUNC/retval
echo N > /sys/kernel/debug/$FAILTYPE/task-filter
echo 100 > /sys/kernel/debug/$FAILTYPE/probability
echo 0 > /sys/kernel/debug/$FAILTYPE/interval
echo -1 > /sys/kernel/debug/$FAILTYPE/times
printf %#x -1 > /sys/kernel/debug/$FAILTYPE/times
echo 0 > /sys/kernel/debug/$FAILTYPE/space
echo 1 > /sys/kernel/debug/$FAILTYPE/verbose

291
Documentation/filesystems/dax.rst Normal file
View File

@ -0,0 +1,291 @@
=======================
Direct Access for files
=======================
Motivation
----------
The page cache is usually used to buffer reads and writes to files.
It is also used to provide the pages which are mapped into userspace
by a call to mmap.
For block devices that are memory-like, the page cache pages would be
unnecessary copies of the original storage. The `DAX` code removes the
extra copy by performing reads and writes directly to the storage device.
For file mappings, the storage device is mapped directly into userspace.
Usage
-----
If you have a block device which supports `DAX`, you can make a filesystem
on it as usual. The `DAX` code currently only supports files with a block
size equal to your kernel's `PAGE_SIZE`, so you may need to specify a block
size when creating the filesystem.
Currently 3 filesystems support `DAX`: ext2, ext4 and xfs. Enabling `DAX` on them
is different.
Enabling DAX on ext2
--------------------
When mounting the filesystem, use the ``-o dax`` option on the command line or
add 'dax' to the options in ``/etc/fstab``. This works to enable `DAX` on all files
within the filesystem. It is equivalent to the ``-o dax=always`` behavior below.
Enabling DAX on xfs and ext4
----------------------------
Summary
-------
1. There exists an in-kernel file access mode flag `S_DAX` that corresponds to
the statx flag `STATX_ATTR_DAX`. See the manpage for statx(2) for details
about this access mode.
2. There exists a persistent flag `FS_XFLAG_DAX` that can be applied to regular
files and directories. This advisory flag can be set or cleared at any
time, but doing so does not immediately affect the `S_DAX` state.
3. If the persistent `FS_XFLAG_DAX` flag is set on a directory, this flag will
be inherited by all regular files and subdirectories that are subsequently
created in this directory. Files and subdirectories that exist at the time
this flag is set or cleared on the parent directory are not modified by
this modification of the parent directory.
4. There exist dax mount options which can override `FS_XFLAG_DAX` in the
setting of the `S_DAX` flag. Given underlying storage which supports `DAX` the
following hold:
``-o dax=inode`` means "follow `FS_XFLAG_DAX`" and is the default.
``-o dax=never`` means "never set `S_DAX`, ignore `FS_XFLAG_DAX`."
``-o dax=always`` means "always set `S_DAX` ignore `FS_XFLAG_DAX`."
``-o dax`` is a legacy option which is an alias for ``dax=always``.
.. warning::
The option ``-o dax`` may be removed in the future so ``-o dax=always`` is
the preferred method for specifying this behavior.
.. note::
Modifications to and the inheritance behavior of `FS_XFLAG_DAX` remain
the same even when the filesystem is mounted with a dax option. However,
in-core inode state (`S_DAX`) will be overridden until the filesystem is
remounted with dax=inode and the inode is evicted from kernel memory.
5. The `S_DAX` policy can be changed via:
a) Setting the parent directory `FS_XFLAG_DAX` as needed before files are
created
b) Setting the appropriate dax="foo" mount option
c) Changing the `FS_XFLAG_DAX` flag on existing regular files and
directories. This has runtime constraints and limitations that are
described in 6) below.
6. When changing the `S_DAX` policy via toggling the persistent `FS_XFLAG_DAX`
flag, the change to existing regular files won't take effect until the
files are closed by all processes.
Details
-------
There are 2 per-file dax flags. One is a persistent inode setting (`FS_XFLAG_DAX`)
and the other is a volatile flag indicating the active state of the feature
(`S_DAX`).
`FS_XFLAG_DAX` is preserved within the filesystem. This persistent config
setting can be set, cleared and/or queried using the `FS_IOC_FS`[`GS`]`ETXATTR` ioctl
(see ioctl_xfs_fsgetxattr(2)) or an utility such as 'xfs_io'.
New files and directories automatically inherit `FS_XFLAG_DAX` from
their parent directory **when created**. Therefore, setting `FS_XFLAG_DAX` at
directory creation time can be used to set a default behavior for an entire
sub-tree.
To clarify inheritance, here are 3 examples:
Example A:
.. code-block:: shell
mkdir -p a/b/c
xfs_io -c 'chattr +x' a
mkdir a/b/c/d
mkdir a/e
------[outcome]------
dax: a,e
no dax: b,c,d
Example B:
.. code-block:: shell
mkdir a
xfs_io -c 'chattr +x' a
mkdir -p a/b/c/d
------[outcome]------
dax: a,b,c,d
no dax:
Example C:
.. code-block:: shell
mkdir -p a/b/c
xfs_io -c 'chattr +x' c
mkdir a/b/c/d
------[outcome]------
dax: c,d
no dax: a,b
The current enabled state (`S_DAX`) is set when a file inode is instantiated in
memory by the kernel. It is set based on the underlying media support, the
value of `FS_XFLAG_DAX` and the filesystem's dax mount option.
statx can be used to query `S_DAX`.
.. note::
That only regular files will ever have `S_DAX` set and therefore statx
will never indicate that `S_DAX` is set on directories.
Setting the `FS_XFLAG_DAX` flag (specifically or through inheritance) occurs even
if the underlying media does not support dax and/or the filesystem is
overridden with a mount option.
Implementation Tips for Block Driver Writers
--------------------------------------------
To support `DAX` in your block driver, implement the 'direct_access'
block device operation. It is used to translate the sector number
(expressed in units of 512-byte sectors) to a page frame number (pfn)
that identifies the physical page for the memory. It also returns a
kernel virtual address that can be used to access the memory.
The direct_access method takes a 'size' parameter that indicates the
number of bytes being requested. The function should return the number
of bytes that can be contiguously accessed at that offset. It may also
return a negative errno if an error occurs.
In order to support this method, the storage must be byte-accessible by
the CPU at all times. If your device uses paging techniques to expose
a large amount of memory through a smaller window, then you cannot
implement direct_access. Equally, if your device can occasionally
stall the CPU for an extended period, you should also not attempt to
implement direct_access.
These block devices may be used for inspiration:
- brd: RAM backed block device driver
- dcssblk: s390 dcss block device driver
- pmem: NVDIMM persistent memory driver
Implementation Tips for Filesystem Writers
------------------------------------------
Filesystem support consists of:
* Adding support to mark inodes as being `DAX` by setting the `S_DAX` flag in
i_flags
* Implementing ->read_iter and ->write_iter operations which use
:c:func:`dax_iomap_rw()` when inode has `S_DAX` flag set
* Implementing an mmap file operation for `DAX` files which sets the
`VM_MIXEDMAP` and `VM_HUGEPAGE` flags on the `VMA`, and setting the vm_ops to
include handlers for fault, pmd_fault, page_mkwrite, pfn_mkwrite. These
handlers should probably call :c:func:`dax_iomap_fault()` passing the
appropriate fault size and iomap operations.
* Calling :c:func:`iomap_zero_range()` passing appropriate iomap operations
instead of :c:func:`block_truncate_page()` for `DAX` files
* Ensuring that there is sufficient locking between reads, writes,
truncates and page faults
The iomap handlers for allocating blocks must make sure that allocated blocks
are zeroed out and converted to written extents before being returned to avoid
exposure of uninitialized data through mmap.
These filesystems may be used for inspiration:
.. seealso::
ext2: see Documentation/filesystems/ext2.rst
.. seealso::
xfs: see Documentation/admin-guide/xfs.rst
.. seealso::
ext4: see Documentation/filesystems/ext4/
Handling Media Errors
---------------------
The libnvdimm subsystem stores a record of known media error locations for
each pmem block device (in gendisk->badblocks). If we fault at such location,
or one with a latent error not yet discovered, the application can expect
to receive a `SIGBUS`. Libnvdimm also allows clearing of these errors by simply
writing the affected sectors (through the pmem driver, and if the underlying
NVDIMM supports the clear_poison DSM defined by ACPI).
Since `DAX` IO normally doesn't go through the ``driver/bio`` path, applications or
sysadmins have an option to restore the lost data from a prior ``backup/inbuilt``
redundancy in the following ways:
1. Delete the affected file, and restore from a backup (sysadmin route):
This will free the filesystem blocks that were being used by the file,
and the next time they're allocated, they will be zeroed first, which
happens through the driver, and will clear bad sectors.
2. Truncate or hole-punch the part of the file that has a bad-block (at least
an entire aligned sector has to be hole-punched, but not necessarily an
entire filesystem block).
These are the two basic paths that allow `DAX` filesystems to continue operating
in the presence of media errors. More robust error recovery mechanisms can be
built on top of this in the future, for example, involving redundancy/mirroring
provided at the block layer through DM, or additionally, at the filesystem
level. These would have to rely on the above two tenets, that error clearing
can happen either by sending an IO through the driver, or zeroing (also through
the driver).
Shortcomings
------------
Even if the kernel or its modules are stored on a filesystem that supports
`DAX` on a block device that supports `DAX`, they will still be copied into RAM.
The DAX code does not work correctly on architectures which have virtually
mapped caches such as ARM, MIPS and SPARC.
Calling :c:func:`get_user_pages()` on a range of user memory that has been
mmaped from a `DAX` file will fail when there are no 'struct page' to describe
those pages. This problem has been addressed in some device drivers
by adding optional struct page support for pages under the control of
the driver (see `CONFIG_NVDIMM_PFN` in ``drivers/nvdimm`` for an example of
how to do this). In the non struct page cases `O_DIRECT` reads/writes to
those memory ranges from a non-`DAX` file will fail
.. note::
`O_DIRECT` reads/writes _of a `DAX` file do work, it is the memory that
is being accessed that is key here). Other things that will not work in
the non struct page case include RDMA, :c:func:`sendfile()` and
:c:func:`splice()`.

257
Documentation/filesystems/dax.txt
View File

@ -1,257 +0,0 @@
Direct Access for files
-----------------------
Motivation
----------
The page cache is usually used to buffer reads and writes to files.
It is also used to provide the pages which are mapped into userspace
by a call to mmap.
For block devices that are memory-like, the page cache pages would be
unnecessary copies of the original storage. The DAX code removes the
extra copy by performing reads and writes directly to the storage device.
For file mappings, the storage device is mapped directly into userspace.
Usage
-----
If you have a block device which supports DAX, you can make a filesystem
on it as usual. The DAX code currently only supports files with a block
size equal to your kernel's PAGE_SIZE, so you may need to specify a block
size when creating the filesystem.
Currently 3 filesystems support DAX: ext2, ext4 and xfs. Enabling DAX on them
is different.
Enabling DAX on ext2
-----------------------------
When mounting the filesystem, use the "-o dax" option on the command line or
add 'dax' to the options in /etc/fstab. This works to enable DAX on all files
within the filesystem. It is equivalent to the '-o dax=always' behavior below.
Enabling DAX on xfs and ext4
----------------------------
Summary
-------
1. There exists an in-kernel file access mode flag S_DAX that corresponds to
the statx flag STATX_ATTR_DAX. See the manpage for statx(2) for details
about this access mode.
2. There exists a persistent flag FS_XFLAG_DAX that can be applied to regular
files and directories. This advisory flag can be set or cleared at any
time, but doing so does not immediately affect the S_DAX state.
3. If the persistent FS_XFLAG_DAX flag is set on a directory, this flag will
be inherited by all regular files and subdirectories that are subsequently
created in this directory. Files and subdirectories that exist at the time
this flag is set or cleared on the parent directory are not modified by
this modification of the parent directory.
4. There exist dax mount options which can override FS_XFLAG_DAX in the
setting of the S_DAX flag. Given underlying storage which supports DAX the
following hold:
"-o dax=inode" means "follow FS_XFLAG_DAX" and is the default.
"-o dax=never" means "never set S_DAX, ignore FS_XFLAG_DAX."
"-o dax=always" means "always set S_DAX ignore FS_XFLAG_DAX."
"-o dax" is a legacy option which is an alias for "dax=always".
This may be removed in the future so "-o dax=always" is
the preferred method for specifying this behavior.
NOTE: Modifications to and the inheritance behavior of FS_XFLAG_DAX remain
the same even when the filesystem is mounted with a dax option. However,
in-core inode state (S_DAX) will be overridden until the filesystem is
remounted with dax=inode and the inode is evicted from kernel memory.
5. The S_DAX policy can be changed via:
a) Setting the parent directory FS_XFLAG_DAX as needed before files are
created
b) Setting the appropriate dax="foo" mount option
c) Changing the FS_XFLAG_DAX flag on existing regular files and
directories. This has runtime constraints and limitations that are
described in 6) below.
6. When changing the S_DAX policy via toggling the persistent FS_XFLAG_DAX
flag, the change to existing regular files won't take effect until the
files are closed by all processes.
Details
-------
There are 2 per-file dax flags. One is a persistent inode setting (FS_XFLAG_DAX)
and the other is a volatile flag indicating the active state of the feature
(S_DAX).
FS_XFLAG_DAX is preserved within the filesystem. This persistent config
setting can be set, cleared and/or queried using the FS_IOC_FS[GS]ETXATTR ioctl
(see ioctl_xfs_fsgetxattr(2)) or an utility such as 'xfs_io'.
New files and directories automatically inherit FS_XFLAG_DAX from
their parent directory _when_ _created_. Therefore, setting FS_XFLAG_DAX at
directory creation time can be used to set a default behavior for an entire
sub-tree.
To clarify inheritance, here are 3 examples:
Example A:
mkdir -p a/b/c
xfs_io -c 'chattr +x' a
mkdir a/b/c/d
mkdir a/e
dax: a,e
no dax: b,c,d
Example B:
mkdir a
xfs_io -c 'chattr +x' a
mkdir -p a/b/c/d
dax: a,b,c,d
no dax:
Example C:
mkdir -p a/b/c
xfs_io -c 'chattr +x' c
mkdir a/b/c/d
dax: c,d
no dax: a,b
The current enabled state (S_DAX) is set when a file inode is instantiated in
memory by the kernel. It is set based on the underlying media support, the
value of FS_XFLAG_DAX and the filesystem's dax mount option.
statx can be used to query S_DAX. NOTE that only regular files will ever have
S_DAX set and therefore statx will never indicate that S_DAX is set on
directories.
Setting the FS_XFLAG_DAX flag (specifically or through inheritance) occurs even
if the underlying media does not support dax and/or the filesystem is
overridden with a mount option.
Implementation Tips for Block Driver Writers
--------------------------------------------
To support DAX in your block driver, implement the 'direct_access'
block device operation. It is used to translate the sector number
(expressed in units of 512-byte sectors) to a page frame number (pfn)
that identifies the physical page for the memory. It also returns a
kernel virtual address that can be used to access the memory.
The direct_access method takes a 'size' parameter that indicates the
number of bytes being requested. The function should return the number
of bytes that can be contiguously accessed at that offset. It may also
return a negative errno if an error occurs.
In order to support this method, the storage must be byte-accessible by
the CPU at all times. If your device uses paging techniques to expose
a large amount of memory through a smaller window, then you cannot
implement direct_access. Equally, if your device can occasionally
stall the CPU for an extended period, you should also not attempt to
implement direct_access.
These block devices may be used for inspiration:
- brd: RAM backed block device driver
- dcssblk: s390 dcss block device driver
- pmem: NVDIMM persistent memory driver
Implementation Tips for Filesystem Writers
------------------------------------------
Filesystem support consists of
- adding support to mark inodes as being DAX by setting the S_DAX flag in
i_flags
- implementing ->read_iter and ->write_iter operations which use dax_iomap_rw()
when inode has S_DAX flag set
- implementing an mmap file operation for DAX files which sets the
VM_MIXEDMAP and VM_HUGEPAGE flags on the VMA, and setting the vm_ops to
include handlers for fault, pmd_fault, page_mkwrite, pfn_mkwrite. These
handlers should probably call dax_iomap_fault() passing the appropriate
fault size and iomap operations.
- calling iomap_zero_range() passing appropriate iomap operations instead of
block_truncate_page() for DAX files
- ensuring that there is sufficient locking between reads, writes,
truncates and page faults
The iomap handlers for allocating blocks must make sure that allocated blocks
are zeroed out and converted to written extents before being returned to avoid
exposure of uninitialized data through mmap.
These filesystems may be used for inspiration:
- ext2: see Documentation/filesystems/ext2.rst
- ext4: see Documentation/filesystems/ext4/
- xfs: see Documentation/admin-guide/xfs.rst
Handling Media Errors
---------------------
The libnvdimm subsystem stores a record of known media error locations for
each pmem block device (in gendisk->badblocks). If we fault at such location,
or one with a latent error not yet discovered, the application can expect
to receive a SIGBUS. Libnvdimm also allows clearing of these errors by simply
writing the affected sectors (through the pmem driver, and if the underlying
NVDIMM supports the clear_poison DSM defined by ACPI).
Since DAX IO normally doesn't go through the driver/bio path, applications or
sysadmins have an option to restore the lost data from a prior backup/inbuilt
redundancy in the following ways:
1. Delete the affected file, and restore from a backup (sysadmin route):
This will free the filesystem blocks that were being used by the file,
and the next time they're allocated, they will be zeroed first, which
happens through the driver, and will clear bad sectors.
2. Truncate or hole-punch the part of the file that has a bad-block (at least
an entire aligned sector has to be hole-punched, but not necessarily an
entire filesystem block).
These are the two basic paths that allow DAX filesystems to continue operating
in the presence of media errors. More robust error recovery mechanisms can be
built on top of this in the future, for example, involving redundancy/mirroring
provided at the block layer through DM, or additionally, at the filesystem
level. These would have to rely on the above two tenets, that error clearing
can happen either by sending an IO through the driver, or zeroing (also through
the driver).
Shortcomings
------------
Even if the kernel or its modules are stored on a filesystem that supports
DAX on a block device that supports DAX, they will still be copied into RAM.
The DAX code does not work correctly on architectures which have virtually
mapped caches such as ARM, MIPS and SPARC.
Calling get_user_pages() on a range of user memory that has been mmaped
from a DAX file will fail when there are no 'struct page' to describe
those pages. This problem has been addressed in some device drivers
by adding optional struct page support for pages under the control of
the driver (see CONFIG_NVDIMM_PFN in drivers/nvdimm for an example of
how to do this). In the non struct page cases O_DIRECT reads/writes to
those memory ranges from a non-DAX file will fail (note that O_DIRECT
reads/writes _of a DAX file_ do work, it is the memory that is being
accessed that is key here). Other things that will not work in the
non struct page case include RDMA, sendfile() and splice().

2
Documentation/filesystems/ext2.rst
View File

@ -25,7 +25,7 @@ check=none, nocheck (*) Don't do extra checking of bitmaps on mount
(check=normal and check=strict options removed)
dax Use direct access (no page cache). See
Documentation/filesystems/dax.txt.
Documentation/filesystems/dax.rst.
debug Extra debugging information is sent to the
kernel syslog. Useful for developers.

2
Documentation/filesystems/ext4/blockgroup.rst
View File

@ -84,7 +84,7 @@ Without the option META\_BG, for safety concerns, all block group
descriptors copies are kept in the first block group. Given the default
128MiB(2^27 bytes) block group size and 64-byte group descriptors, ext4
can have at most 2^27/64 = 2^21 block groups. This limits the entire
filesystem size to 2^21 ∗ 2^27 = 2^48bytes or 256TiB.
filesystem size to 2^21 * 2^27 = 2^48bytes or 256TiB.
The solution to this problem is to use the metablock group feature
(META\_BG), which is already in ext3 for all 2.6 releases. With the

1
Documentation/filesystems/index.rst
View File

@ -77,6 +77,7 @@ Documentation for filesystem implementations.
coda
configfs
cramfs
dax
debugfs
dlmfs
ecryptfs

186
Documentation/filesystems/path-lookup.rst
View File

@ -448,15 +448,17 @@ described. If it finds a ``LAST_NORM`` component it first calls
filesystem to revalidate the result if it is that sort of filesystem.
If that doesn't get a good result, it calls "``lookup_slow()``" which
takes ``i_rwsem``, rechecks the cache, and then asks the filesystem
to find a definitive answer. Each of these will call
``follow_managed()`` (as described below) to handle any mount points.
to find a definitive answer.
In the absence of symbolic links, ``walk_component()`` creates a new
``struct path`` containing a counted reference to the new dentry and a
reference to the new ``vfsmount`` which is only counted if it is
different from the previous ``vfsmount``. It then calls
``path_to_nameidata()`` to install the new ``struct path`` in the
``struct nameidata`` and drop the unneeded references.
As the last step of walk_component(), step_into() will be called either
directly from walk_component() or from handle_dots(). It calls
handle_mounts(), to check and handle mount points, in which a new
``struct path`` is created containing a counted reference to the new dentry and
a reference to the new ``vfsmount`` which is only counted if it is
different from the previous ``vfsmount``. Then if there is
a symbolic link, step_into() calls pick_link() to deal with it,
otherwise it installs the new ``struct path`` in the ``struct nameidata``, and
drops the unneeded references.
This "hand-over-hand" sequencing of getting a reference to the new
dentry before dropping the reference to the previous dentry may
@ -470,8 +472,8 @@ Handling the final component
``nd->last_type`` to refer to the final component of the path. It does
not call ``walk_component()`` that last time. Handling that final
component remains for the caller to sort out. Those callers are
``path_lookupat()``, ``path_parentat()``, ``path_mountpoint()`` and
``path_openat()`` each of which handles the differing requirements of
path_lookupat(), path_parentat() and
path_openat() each of which handles the differing requirements of
different system calls.
``path_parentat()`` is clearly the simplest - it just wraps a little bit
@ -486,20 +488,18 @@ perform their operation.
object is wanted such as by ``stat()`` or ``chmod()``. It essentially just
calls ``walk_component()`` on the final component through a call to
``lookup_last()``. ``path_lookupat()`` returns just the final dentry.
``path_mountpoint()`` handles the special case of unmounting which must
not try to revalidate the mounted filesystem. It effectively
contains, through a call to ``mountpoint_last()``, an alternate
implementation of ``lookup_slow()`` which skips that step. This is
important when unmounting a filesystem that is inaccessible, such as
It is worth noting that when flag ``LOOKUP_MOUNTPOINT`` is set,
path_lookupat() will unset LOOKUP_JUMPED in nameidata so that in the
subsequent path traversal d_weak_revalidate() won't be called.
This is important when unmounting a filesystem that is inaccessible, such as
one provided by a dead NFS server.
Finally ``path_openat()`` is used for the ``open()`` system call; it
contains, in support functions starting with "``do_last()``", all the
contains, in support functions starting with "open_last_lookups()", all the
complexity needed to handle the different subtleties of O_CREAT (with
or without O_EXCL), final "``/``" characters, and trailing symbolic
links. We will revisit this in the final part of this series, which
focuses on those symbolic links. "``do_last()``" will sometimes, but
focuses on those symbolic links. "open_last_lookups()" will sometimes, but
not always, take ``i_rwsem``, depending on what it finds.
Each of these, or the functions which call them, need to be alert to
@ -535,8 +535,7 @@ covered in greater detail in autofs.txt in the Linux documentation
tree, but a few notes specifically related to path lookup are in order
here.
The Linux VFS has a concept of "managed" dentries which is reflected
in function names such as "``follow_managed()``". There are three
The Linux VFS has a concept of "managed" dentries. There are three
potentially interesting things about these dentries corresponding
to three different flags that might be set in ``dentry->d_flags``:
@ -652,10 +651,10 @@ RCU-walk finds it cannot stop gracefully, it simply gives up and
restarts from the top with REF-walk.
This pattern of "try RCU-walk, if that fails try REF-walk" can be
clearly seen in functions like ``filename_lookup()``,
``filename_parentat()``, ``filename_mountpoint()``,
``do_filp_open()``, and ``do_file_open_root()``. These five
correspond roughly to the four ``path_*()`` functions we met earlier,
clearly seen in functions like filename_lookup(),
filename_parentat(),
do_filp_open(), and do_file_open_root(). These four
correspond roughly to the three ``path_*()`` functions we met earlier,
each of which calls ``link_path_walk()``. The ``path_*()`` functions are
called using different mode flags until a mode is found which works.
They are first called with ``LOOKUP_RCU`` set to request "RCU-walk". If
@ -993,8 +992,8 @@ is 4096. There are a number of reasons for this limit; not letting the
kernel spend too much time on just one path is one of them. With
symbolic links you can effectively generate much longer paths so some
sort of limit is needed for the same reason. Linux imposes a limit of
at most 40 symlinks in any one path lookup. It previously imposed a
further limit of eight on the maximum depth of recursion, but that was
at most 40 (MAXSYMLINKS) symlinks in any one path lookup. It previously imposed
a further limit of eight on the maximum depth of recursion, but that was
raised to 40 when a separate stack was implemented, so there is now
just the one limit.
@ -1061,42 +1060,26 @@ filesystem cannot successfully get a reference in RCU-walk mode, it
must return ``-ECHILD`` and ``unlazy_walk()`` will be called to return to
REF-walk mode in which the filesystem is allowed to sleep.
The place for all this to happen is the ``i_op->follow_link()`` inode
method. In the present mainline code this is never actually called in
RCU-walk mode as the rewrite is not quite complete. It is likely that
in a future release this method will be passed an ``inode`` pointer when
called in RCU-walk mode so it both (1) knows to be careful, and (2) has the
validated pointer. Much like the ``i_op->permission()`` method we
looked at previously, ``->follow_link()`` would need to be careful that
The place for all this to happen is the ``i_op->get_link()`` inode
method. This is called both in RCU-walk and REF-walk. In RCU-walk the
``dentry*`` argument is NULL, ``->get_link()`` can return -ECHILD to drop out of
RCU-walk. Much like the ``i_op->permission()`` method we
looked at previously, ``->get_link()`` would need to be careful that
all the data structures it references are safe to be accessed while
holding no counted reference, only the RCU lock. Though getting a
reference with ``->follow_link()`` is not yet done in RCU-walk mode, the
code is ready to release the reference when that does happen.
This need to drop the reference to a symlink adds significant
complexity. It requires a reference to the inode so that the
``i_op->put_link()`` inode operation can be called. In REF-walk, that
reference is kept implicitly through a reference to the dentry, so
keeping the ``struct path`` of the symlink is easiest. For RCU-walk,
the pointer to the inode is kept separately. To allow switching from
RCU-walk back to REF-walk in the middle of processing nested symlinks
we also need the seq number for the dentry so we can confirm that
switching back was safe.
Finally, when providing a reference to a symlink, the filesystem also
provides an opaque "cookie" that must be passed to ``->put_link()`` so that it
knows what to free. This might be the allocated memory area, or a
pointer to the ``struct page`` in the page cache, or something else
completely. Only the filesystem knows what it is.
holding no counted reference, only the RCU lock. A callback
``struct delayed_called`` will be passed to ``->get_link()``:
file systems can set their own put_link function and argument through
set_delayed_call(). Later on, when VFS wants to put link, it will call
do_delayed_call() to invoke that callback function with the argument.
In order for the reference to each symlink to be dropped when the walk completes,
whether in RCU-walk or REF-walk, the symlink stack needs to contain,
along with the path remnants:
- the ``struct path`` to provide a reference to the inode in REF-walk
- the ``struct inode *`` to provide a reference to the inode in RCU-walk
- the ``struct path`` to provide a reference to the previous path
- the ``const char *`` to provide a reference to the to previous name
- the ``seq`` to allow the path to be safely switched from RCU-walk to REF-walk
- the ``cookie`` that tells ``->put_path()`` what to put.
- the ``struct delayed_call`` for later invocation.
This means that each entry in the symlink stack needs to hold five
pointers and an integer instead of just one pointer (the path
@ -1120,12 +1103,10 @@ doesn't need to notice. Getting this ``name`` variable on and off the
stack is very straightforward; pushing and popping the references is
a little more complex.
When a symlink is found, ``walk_component()`` returns the value ``1``
(``0`` is returned for any other sort of success, and a negative number
is, as usual, an error indicator). This causes ``get_link()`` to be
called; it then gets the link from the filesystem. Providing that
operation is successful, the old path ``name`` is placed on the stack,
and the new value is used as the ``name`` for a while. When the end of
When a symlink is found, walk_component() calls pick_link() via step_into()
which returns the link from the filesystem.
Providing that operation is successful, the old path ``name`` is placed on the
stack, and the new value is used as the ``name`` for a while. When the end of
the path is found (i.e. ``*name`` is ``'\0'``) the old ``name`` is restored
off the stack and path walking continues.
@ -1142,23 +1123,23 @@ stack in ``walk_component()`` immediately when the symlink is found;
old symlink as it walks that last component. So it is quite
convenient for ``walk_component()`` to release the old symlink and pop
the references just before pushing the reference information for the
new symlink. It is guided in this by two flags; ``WALK_GET``, which
gives it permission to follow a symlink if it finds one, and
``WALK_PUT``, which tells it to release the current symlink after it has been
followed. ``WALK_PUT`` is tested first, leading to a call to
``put_link()``. ``WALK_GET`` is tested subsequently (by
``should_follow_link()``) leading to a call to ``pick_link()`` which sets
up the stack frame.
new symlink. It is guided in this by three flags: ``WALK_NOFOLLOW`` which
forbids it from following a symlink if it finds one, ``WALK_MORE``
which indicates that it is yet too early to release the
current symlink, and ``WALK_TRAILING`` which indicates that it is on the final
component of the lookup, so we will check userspace flag ``LOOKUP_FOLLOW`` to
decide whether follow it when it is a symlink and call ``may_follow_link()`` to
check if we have privilege to follow it.
Symlinks with no final component
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
A pair of special-case symlinks deserve a little further explanation.
Both result in a new ``struct path`` (with mount and dentry) being set
up in the ``nameidata``, and result in ``get_link()`` returning ``NULL``.
up in the ``nameidata``, and result in pick_link() returning ``NULL``.
The more obvious case is a symlink to "``/``". All symlinks starting
with "``/``" are detected in ``get_link()`` which resets the ``nameidata``
with "``/``" are detected in pick_link() which resets the ``nameidata``
to point to the effective filesystem root. If the symlink only
contains "``/``" then there is nothing more to do, no components at all,
so ``NULL`` is returned to indicate that the symlink can be released and
@ -1175,12 +1156,11 @@ something that looks like a symlink. It is really a reference to the
target file, not just the name of it. When you ``readlink`` these
objects you get a name that might refer to the same file - unless it
has been unlinked or mounted over. When ``walk_component()`` follows
one of these, the ``->follow_link()`` method in "procfs" doesn't return
a string name, but instead calls ``nd_jump_link()`` which updates the
``nameidata`` in place to point to that target. ``->follow_link()`` then
returns ``NULL``. Again there is no final component and ``get_link()``
reports this by leaving the ``last_type`` field of ``nameidata`` as
``LAST_BIND``.
one of these, the ``->get_link()`` method in "procfs" doesn't return
a string name, but instead calls nd_jump_link() which updates the
``nameidata`` in place to point to that target. ``->get_link()`` then
returns ``NULL``. Again there is no final component and pick_link()
returns ``NULL``.
Following the symlink in the final component
--------------------------------------------
@ -1197,42 +1177,38 @@ potentially need to call ``link_path_walk()`` again and again on
successive symlinks until one is found that doesn't point to another
symlink.
This case is handled by the relevant caller of ``link_path_walk()``, such as
``path_lookupat()`` using a loop that calls ``link_path_walk()``, and then
handles the final component. If the final component is a symlink
that needs to be followed, then ``trailing_symlink()`` is called to set
things up properly and the loop repeats, calling ``link_path_walk()``
again. This could loop as many as 40 times if the last component of
each symlink is another symlink.
This case is handled by relevant callers of link_path_walk(), such as
path_lookupat(), path_openat() using a loop that calls link_path_walk(),
and then handles the final component by calling open_last_lookups() or
lookup_last(). If it is a symlink that needs to be followed,
open_last_lookups() or lookup_last() will set things up properly and
return the path so that the loop repeats, calling
link_path_walk() again. This could loop as many as 40 times if the last
component of each symlink is another symlink.
The various functions that examine the final component and possibly
report that it is a symlink are ``lookup_last()``, ``mountpoint_last()``
and ``do_last()``, each of which use the same convention as
``walk_component()`` of returning ``1`` if a symlink was found that needs
to be followed.
Of the various functions that examine the final component,
open_last_lookups() is the most interesting as it works in tandem
with do_open() for opening a file. Part of open_last_lookups() runs
with ``i_rwsem`` held and this part is in a separate function: lookup_open().
Of these, ``do_last()`` is the most interesting as it is used for
opening a file. Part of ``do_last()`` runs with ``i_rwsem`` held and this
part is in a separate function: ``lookup_open()``.
Explaining open_last_lookups() and do_open() completely is beyond the scope
of this article, but a few highlights should help those interested in exploring
the code.
Explaining ``do_last()`` completely is beyond the scope of this article,
but a few highlights should help those interested in exploring the
code.
1. Rather than just finding the target file, ``do_last()`` needs to open
1. Rather than just finding the target file, do_open() is used after
open_last_lookup() to open
it. If the file was found in the dcache, then ``vfs_open()`` is used for
this. If not, then ``lookup_open()`` will either call ``atomic_open()`` (if
the filesystem provides it) to combine the final lookup with the open, or
will perform the separate ``lookup_real()`` and ``vfs_create()`` steps
will perform the separate ``i_op->lookup()`` and ``i_op->create()`` steps
directly. In the later case the actual "open" of this newly found or
created file will be performed by ``vfs_open()``, just as if the name
created file will be performed by vfs_open(), just as if the name
were found in the dcache.
2. ``vfs_open()`` can fail with ``-EOPENSTALE`` if the cached information
wasn't quite current enough. Rather than restarting the lookup from
the top with ``LOOKUP_REVAL`` set, ``lookup_open()`` is called instead,
giving the filesystem a chance to resolve small inconsistencies.
If that doesn't work, only then is the lookup restarted from the top.
2. vfs_open() can fail with ``-EOPENSTALE`` if the cached information
wasn't quite current enough. If it's in RCU-walk ``-ECHILD`` will be returned
otherwise ``-ESTALE`` is returned. When ``-ESTALE`` is returned, the caller may
retry with ``LOOKUP_REVAL`` flag set.
3. An open with O_CREAT **does** follow a symlink in the final component,
unlike other creation system calls (like ``mkdir``). So the sequence::
@ -1242,8 +1218,8 @@ code.
will create a file called ``/tmp/bar``. This is not permitted if
``O_EXCL`` is set but otherwise is handled for an O_CREAT open much
like for a non-creating open: ``should_follow_link()`` returns ``1``, and
so does ``do_last()`` so that ``trailing_symlink()`` gets called and the
like for a non-creating open: lookup_last() or open_last_lookup()
returns a non ``NULL`` value, and link_path_walk() gets called and the
open process continues on the symlink that was found.
Updating the access time

3
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@ -79,7 +79,8 @@ the ANOD object which is also the final target node of the reference.
})
}
Please also see a graph example in :doc:`graph`.
Please also see a graph example in
Documentation/firmware-guide/acpi/dsd/graph.rst.
References
==========

2
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@ -174,4 +174,4 @@ References
referenced 2016-10-04.
[7] _DSD Device Properties Usage Rules.
:doc:`../DSD-properties-rules`
Documentation/firmware-guide/acpi/DSD-properties-rules.rst

7
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@ -339,8 +339,8 @@ a code like this::
There are also devm_* versions of these functions which release the
descriptors once the device is released.
See Documentation/firmware-guide/acpi/gpio-properties.rst for more information about the
_DSD binding related to GPIOs.
See Documentation/firmware-guide/acpi/gpio-properties.rst for more information
about the _DSD binding related to GPIOs.
MFD devices
===========
@ -460,7 +460,8 @@ the _DSD of the device object itself or the _DSD of its ancestor in the
Otherwise, the _DSD itself is regarded as invalid and therefore the "compatible"
property returned by it is meaningless.
Refer to :doc:`DSD-properties-rules` for more information.
Refer to Documentation/firmware-guide/acpi/DSD-properties-rules.rst for more
information.
PCI hierarchy representation
============================

2
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@ -59,7 +59,7 @@ Declare the I2C devices via ACPI
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
ACPI can also describe I2C devices. There is special documentation for this
which is currently located at :doc:`../firmware-guide/acpi/enumeration`.
which is currently located at Documentation/firmware-guide/acpi/enumeration.rst.
Declare the I2C devices in board files

3
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@ -17,7 +17,8 @@ address), ``force`` (to forcibly attach the driver to a given device) and
With the conversion of the I2C subsystem to the standard device driver
binding model, it became clear that these per-module parameters were no
longer needed, and that a centralized implementation was possible. The new,
sysfs-based interface is described in :doc:`instantiating-devices`, section
sysfs-based interface is described in
Documentation/i2c/instantiating-devices.rst, section
"Method 4: Instantiate from user-space".
Below is a mapping from the old module parameters to the new interface.

4
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@ -27,8 +27,8 @@ a different protocol operation entirely.
Each transaction type corresponds to a functionality flag. Before calling a
transaction function, a device driver should always check (just once) for
the corresponding functionality flag to ensure that the underlying I2C
adapter supports the transaction in question. See :doc:`functionality` for
the details.
adapter supports the transaction in question. See
Documentation/i2c/functionality.rst for the details.
Key to symbols

2
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@ -263,7 +263,7 @@ possible overrun should the name be too long::
char name[128];
if (ioctl(fd, JSIOCGNAME(sizeof(name)), name) < 0)
strncpy(name, "Unknown", sizeof(name));
strscpy(name, "Unknown", sizeof(name));
printf("Name: %s\n", name);

4
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@ -601,7 +601,7 @@ Defined in ``include/linux/export.h``
This is the variant of `EXPORT_SYMBOL()` that allows specifying a symbol
namespace. Symbol Namespaces are documented in
:doc:`../core-api/symbol-namespaces`
Documentation/core-api/symbol-namespaces.rst
:c:func:`EXPORT_SYMBOL_NS_GPL()`
--------------------------------
@ -610,7 +610,7 @@ Defined in ``include/linux/export.h``
This is the variant of `EXPORT_SYMBOL_GPL()` that allows specifying a symbol
namespace. Symbol Namespaces are documented in
:doc:`../core-api/symbol-namespaces`
Documentation/core-api/symbol-namespaces.rst
Routines and Conventions
========================

6
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@ -466,7 +466,7 @@ network. PTP support varies among Intel devices that support this driver. Use
"ethtool -T <netdev name>" to get a definitive list of PTP capabilities
supported by the device.
IEEE 802.1ad (QinQ) Support
IEEE 802.1ad (QinQ) Support
---------------------------
The IEEE 802.1ad standard, informally known as QinQ, allows for multiple VLAN
IDs within a single Ethernet frame. VLAN IDs are sometimes referred to as
@ -523,8 +523,8 @@ of a port's bandwidth (should it be available). The sum of all the values for
Maximum Bandwidth is not restricted, because no more than 100% of a port's
bandwidth can ever be used.
NOTE: X710/XXV710 devices fail to enable Max VFs (64) when Multiple Functions
per Port (MFP) and SR-IOV are enabled. An error from i40e is logged that says
NOTE: X710/XXV710 devices fail to enable Max VFs (64) when Multiple Functions
per Port (MFP) and SR-IOV are enabled. An error from i40e is logged that says
"add vsi failed for VF N, aq_err 16". To workaround the issue, enable less than
64 virtual functions (VFs).

2
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@ -113,7 +113,7 @@ which the AVF is associated. The following are base mode features:
- AVF device ID
- HW mailbox is used for VF to PF communications (including on Windows)
IEEE 802.1ad (QinQ) Support
IEEE 802.1ad (QinQ) Support
---------------------------
The IEEE 802.1ad standard, informally known as QinQ, allows for multiple VLAN
IDs within a single Ethernet frame. VLAN IDs are sometimes referred to as

2
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@ -22,7 +22,7 @@ The major benefit to creating a region is to provide access to internal
address regions that are otherwise inaccessible to the user.
Regions may also be used to provide an additional way to debug complex error
states, but see also :doc:`devlink-health`
states, but see also Documentation/networking/devlink/devlink-health.rst
Regions may optionally support capturing a snapshot on demand via the
``DEVLINK_CMD_REGION_NEW`` netlink message. A driver wishing to allow

4
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@ -495,8 +495,8 @@ help debug packet drops caused by these exceptions. The following list includes
links to the description of driver-specific traps registered by various device
drivers:
* :doc:`netdevsim`
* :doc:`mlxsw`
* Documentation/networking/devlink/netdevsim.rst
* Documentation/networking/devlink/mlxsw.rst
.. _Generic-Packet-Trap-Groups:

2
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@ -153,7 +153,7 @@ As capture, each frame contains two parts::
struct ifreq s_ifr;
...
strncpy (s_ifr.ifr_name, "eth0", sizeof(s_ifr.ifr_name));
strscpy_pad (s_ifr.ifr_name, "eth0", sizeof(s_ifr.ifr_name));
/* get interface index of eth0 */
ioctl(this->socket, SIOCGIFINDEX, &s_ifr);

2
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@ -107,7 +107,7 @@ Note that the character pointer becomes overwritten with the real device name
*/
ifr.ifr_flags = IFF_TUN;
if( *dev )
strncpy(ifr.ifr_name, dev, IFNAMSIZ);
strscpy_pad(ifr.ifr_name, dev, IFNAMSIZ);
if( (err = ioctl(fd, TUNSETIFF, (void *) &ifr)) < 0 ){
close(fd);

28
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@ -10,10 +10,11 @@ can greatly increase the chances of your change being accepted.
This document contains a large number of suggestions in a relatively terse
format. For detailed information on how the kernel development process
works, see :doc:`development-process`. Also, read :doc:`submit-checklist`
works, see Documentation/process/development-process.rst. Also, read
Documentation/process/submit-checklist.rst
for a list of items to check before submitting code. If you are submitting
a driver, also read :doc:`submitting-drivers`; for device tree binding patches,
read :doc:`submitting-patches`.
a driver, also read Documentation/process/submitting-drivers.rst; for device
tree binding patches, read Documentation/process/submitting-patches.rst.
This documentation assumes that you're using ``git`` to prepare your patches.
If you're unfamiliar with ``git``, you would be well-advised to learn how to
@ -178,8 +179,7 @@ Style-check your changes
------------------------
Check your patch for basic style violations, details of which can be
found in
:ref:`Documentation/process/coding-style.rst <codingstyle>`.
found in Documentation/process/coding-style.rst.
Failure to do so simply wastes
the reviewers time and will get your patch rejected, probably
without even being read.
@ -238,7 +238,7 @@ If you have a patch that fixes an exploitable security bug, send that patch
to security@kernel.org. For severe bugs, a short embargo may be considered
to allow distributors to get the patch out to users; in such cases,
obviously, the patch should not be sent to any public lists. See also
:doc:`/admin-guide/security-bugs`.
Documentation/admin-guide/security-bugs.rst.
Patches that fix a severe bug in a released kernel should be directed
toward the stable maintainers by putting a line like this::
@ -246,9 +246,8 @@ toward the stable maintainers by putting a line like this::
Cc: stable@vger.kernel.org
into the sign-off area of your patch (note, NOT an email recipient). You
should also read
:ref:`Documentation/process/stable-kernel-rules.rst <stable_kernel_rules>`
in addition to this file.
should also read Documentation/process/stable-kernel-rules.rst
in addition to this document.
If changes affect userland-kernel interfaces, please send the MAN-PAGES
maintainer (as listed in the MAINTAINERS file) a man-pages patch, or at
@ -305,8 +304,8 @@ decreasing the likelihood of your MIME-attached change being accepted.
Exception: If your mailer is mangling patches then someone may ask
you to re-send them using MIME.
See :doc:`/process/email-clients` for hints about configuring your e-mail
client so that it sends your patches untouched.
See Documentation/process/email-clients.rst for hints about configuring
your e-mail client so that it sends your patches untouched.
Respond to review comments
--------------------------
@ -324,7 +323,7 @@ for their time. Code review is a tiring and time-consuming process, and
reviewers sometimes get grumpy. Even in that case, though, respond
politely and address the problems they have pointed out.
See :doc:`email-clients` for recommendations on email
See Documentation/process/email-clients.rst for recommendations on email
clients and mailing list etiquette.
@ -564,7 +563,7 @@ for more details.
Note: Attaching a Fixes: tag does not subvert the stable kernel rules
process nor the requirement to Cc: stable@vger.kernel.org on all stable
patch candidates. For more information, please read
:ref:`Documentation/process/stable-kernel-rules.rst <stable_kernel_rules>`
Documentation/process/stable-kernel-rules.rst.
.. _the_canonical_patch_format:
@ -824,8 +823,7 @@ Greg Kroah-Hartman, "How to piss off a kernel subsystem maintainer".
NO!!!! No more huge patch bombs to linux-kernel@vger.kernel.org people!
<https://lore.kernel.org/r/20050711.125305.08322243.davem@davemloft.net>
Kernel Documentation/process/coding-style.rst:
:ref:`Documentation/process/coding-style.rst <codingstyle>`
Kernel Documentation/process/coding-style.rst
Linus Torvalds's mail on the canonical patch format:
<https://lore.kernel.org/r/Pine.LNX.4.58.0504071023190.28951@ppc970.osdl.org>

2
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@ -29,7 +29,7 @@ Quota and period are managed within the cpu subsystem via cgroupfs.
.. note::
The cgroupfs files described in this section are only applicable
to cgroup v1. For cgroup v2, see
:ref:`Documentation/admin-guide/cgroupv2.rst <cgroup-v2-cpu>`.
:ref:`Documentation/admin-guide/cgroup-v2.rst <cgroup-v2-cpu>`.
- cpu.cfs_quota_us: the total available run-time within a period (in
microseconds)

2
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@ -60,7 +60,7 @@ within the constraints of HZ and jiffies and their nasty design level
coupling to timeslices and granularity it was not really viable.
The second (less frequent but still periodically occurring) complaint
about Linux's nice level support was its assymetry around the origo
about Linux's nice level support was its asymmetry around the origin
(which you can see demonstrated in the picture above), or more
accurately: the fact that nice level behavior depended on the _absolute_
nice level as well, while the nice API itself is fundamentally

3
Documentation/security/landlock.rst
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@ -25,7 +25,8 @@ Any user can enforce Landlock rulesets on their processes. They are merged and
evaluated according to the inherited ones in a way that ensures that only more
constraints can be added.
User space documentation can be found here: :doc:`/userspace-api/landlock`.
User space documentation can be found here:
Documentation/userspace-api/landlock.rst.
Guiding principles for safe access controls
===========================================

2
Documentation/trace/coresight/coresight-etm4x-reference.rst
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@ -427,7 +427,7 @@ the ‘TRC’ prefix.
:Syntax:
``echo idx > vmid_idx``
Where idx <  numvmidc
Where idx < numvmidc
----

8
Documentation/trace/coresight/coresight.rst
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@ -315,7 +315,8 @@ intermediate links as required.
Note: ``cti_sys0`` appears in two of the connections lists above.
CTIs can connect to multiple devices and are arranged in a star topology
via the CTM. See (:doc:`coresight-ect`) [#fourth]_ for further details.
via the CTM. See (Documentation/trace/coresight/coresight-ect.rst)
[#fourth]_ for further details.
Looking at this device we see 4 connections::
linaro-developer:~# ls -l /sys/bus/coresight/devices/cti_sys0/connections
@ -606,7 +607,8 @@ interface provided for that purpose by the generic STM API::
crw------- 1 root root 10, 61 Jan 3 18:11 /dev/stm0
root@genericarmv8:~#
Details on how to use the generic STM API can be found here:- :doc:`../stm` [#second]_.
Details on how to use the generic STM API can be found here:
- Documentation/trace/stm.rst [#second]_.
The CTI & CTM Modules
---------------------
@ -616,7 +618,7 @@ individual CTIs and components, and can propagate these between all CTIs via
channels on the CTM (Cross Trigger Matrix).
A separate documentation file is provided to explain the use of these devices.
(:doc:`coresight-ect`) [#fourth]_.
(Documentation/trace/coresight/coresight-ect.rst) [#fourth]_.
.. [#first] Documentation/ABI/testing/sysfs-bus-coresight-devices-stm

6
Documentation/trace/ftrace.rst
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@ -40,7 +40,7 @@ See events.rst for more information.
Implementation Details
----------------------
See :doc:`ftrace-design` for details for arch porters and such.
See Documentation/trace/ftrace-design.rst for details for arch porters and such.
The File System
@ -354,8 +354,8 @@ of ftrace. Here is a list of some of the key files:
is being directly called by the function. If the count is greater
than 1 it most likely will be ftrace_ops_list_func().
If the callback of the function jumps to a trampoline that is
specific to a the callback and not the standard trampoline,
If the callback of a function jumps to a trampoline that is
specific to the callback and which is not the standard trampoline,
its address will be printed as well as the function that the
trampoline calls.

4
Documentation/translations/index.rst
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@ -18,6 +18,10 @@ Translations
Disclaimer
----------
.. raw:: latex
\kerneldocCJKoff
Translation's purpose is to ease reading and understanding in languages other
than English. Its aim is to help people who do not understand English or have
doubts about its interpretation. Additionally, some people prefer to read

4
Documentation/translations/it_IT/index.rst
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@ -4,6 +4,10 @@
Traduzione italiana
===================
.. raw:: latex
\kerneldocCJKoff
:manutentore: Federico Vaga <federico.vaga@vaga.pv.it>
.. _it_disclaimer:

2
Documentation/translations/it_IT/process/coding-style.rst
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@ -62,7 +62,7 @@ i ``case``. Un esempio.:
case 'K':
case 'k':
mem <<= 10;
/* fall through */
fallthrough;
default:
break;
}

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