Roland Dreier reports that one of his systems cannot boot because of
the changes made by commit ac212b6980 (ACPI / processor: Use common
hotplug infrastructure).
The problematic part of it is the request_region() call in
acpi_processor_get_info() that used to run at module init time before
the above commit and now it runs much earlier. Unfortunately, the
region(s) reserved by it fall into a range the PCI subsystem attempts
to reserve for AHCI IO BARs. As a result, the PCI reservation fails
and AHCI doesn't work, while previously the PCI reservation would
be made before acpi_processor_get_info() and it would succeed.
That request_region() call, however, was overlooked by commit
ac212b6980, as it is not necessary for the enumeration of the
processors. It only is needed when the ACPI processor driver
actually attempts to handle them which doesn't happen before
loading the ACPI processor driver module. Therefore that call
should have been moved from acpi_processor_get_info() into that
module.
Address the problem by moving the request_region() call in question
out of acpi_processor_get_info() and use the observation that the
region reserved by it is only needed if the FADT-based CPU
throttling method is going to be used, which means that it should
be sufficient to invoke it from acpi_processor_get_throttling_fadt().
Fixes: ac212b6980 (ACPI / processor: Use common hotplug infrastructure)
Reported-by: Roland Dreier <roland@purestorage.com>
Tested-by: Roland Dreier <roland@purestorage.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
There are several reports of freeze on enabling HWP (Hardware PStates)
feature on Skylake-based systems by the Intel P-states driver. The root
cause is identified as the HWP interrupts causing BIOS code to freeze.
HWP interrupts use the thermal LVT which can be handled by Linux
natively, but on the affected Skylake-based systems SMM will respond
to it by default. This is a problem for several reasons:
- On the affected systems the SMM thermal LVT handler is broken (it
will crash when invoked) and a BIOS update is necessary to fix it.
- With thermal interrupt handled in SMM we lose all of the reporting
features of the arch/x86/kernel/cpu/mcheck/therm_throt driver.
- Some thermal drivers like x86-package-temp depend on the thermal
threshold interrupts signaled via the thermal LVT.
- The HWP interrupts are useful for debugging and tuning
performance (if the kernel can handle them).
The native handling of thermal interrupts needs to be enabled
because of that.
This requires some way to tell SMM that the OS can handle thermal
interrupts. That can be done by using _OSC/_PDC in processor
scope very early during ACPI initialization.
The meaning of _OSC/_PDC bit 12 in processor scope is whether or
not the OS supports native handling of interrupts for Collaborative
Processor Performance Control (CPPC) notifications. Since on
HWP-capable systems CPPC is a firmware interface to HWP, setting
this bit effectively tells the firmware that the OS will handle
thermal interrupts natively going forward.
For details on _OSC/_PDC refer to:
http://www.intel.com/content/www/us/en/standards/processor-vendor-specific-acpi-specification.html
To implement the _OSC/_PDC handshake as described, introduce a new
function, acpi_early_processor_osc(), that walks the ACPI
namespace looking for ACPI processor objects and invokes _OSC for
them with bit 12 in the capabilities buffer set and terminates the
namespace walk on the first success.
Also modify intel_thermal_interrupt() to clear HWP status bits in
the HWP_STATUS MSR to acknowledge HWP interrupts (which prevents
them from firing continuously).
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
[ rjw: Subject & changelog, function rename ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
ACPI 6.0 adds support for optional processor container device which may
contain child objects that are either processor devices or other processor
containers. This allows representing hierarchical processor topologies.
It is declared using the _HID of ACPI0010. It is an abstract container
used to represent CPU topology and should not be used to hotplug
purposes.
If no matching handler is found for a device in acpi_scan_attach_handler,
acpi_bus_attach does a default enumeration for those devices with valid
HID in the acpi namespace. This patch adds a scan handler for these ACPI
processor containers to avoid default that enumeration and ensures the
platform devices are not created for them.
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Add weak functions for architectures which do not support
hot-adding and removing CPUs which aren't detected at
bootup. (e.g. via MADT).
This helps preserve the Kconfig dependency from:
commit cbfc1bae55 ("[ACPI] ACPI_HOTPLUG_CPU Kconfig dependency
update")
prevent:
HOTPLUG_CPU=y
ACPI_PROCESSOR=y
ACPI_HOTPLUG_CPU=n
Signed-off-by: Ashwin Chaugule <ashwin.chaugule@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The processor_handler structure does not reference any __init / __exit
code or data. Therefore the __refdata annotation is not needed. It used
to be prior to commit fe7bf106eb ("acpi: delete __cpuinit usage from
all acpi files") due to the __cpuinit annotation of acpi_processor_add().
But with that commit in place that requirement has gone.
The same is true for the acpi_cpu_notifier notifier block.
acpi_cpu_soft_notify() used to be marked __cpuinit but lost its
annotation in the above mentioned commit as well. Therefore the __refdata
annotation isn't needed there either.
Just drop the unneded __refdata annotations to be able to catch future
section mismatches.
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Introduce invalid_phys_cpuid() to identify cpu with invalid
physical ID, then used it as replacement of the direct comparisons
with PHYS_CPUID_INVALID.
Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Use pr->phys_id to replace phys_id to simplify the code.
Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Just use pr->id instead of cpu_index to simplify the code.
Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
In ACPI processor drivers, we use direct comparisons of cpu logical
id with -1 which are error prone in case logical cpuid is accidentally
assinged an error code and prevents us from returning an error-encoding
cpuid directly in some cases.
So introduce invalid_logical_cpuid() to identify cpu with invalid
logical cpu num, then it will be used to replace the direct comparisons
with -1.
Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
CPU hardware ID (phys_id) is defined as u32 in structure acpi_processor,
but phys_id is used as int in acpi processor driver, so it will lead to
some inconsistence for the drivers.
Furthermore, to cater for ACPI arch ports that implement 64 bits CPU
ids a generic CPU physical id type is required.
So introduce typedef u32 phys_cpuid_t in a common file, and introduce
a macro PHYS_CPUID_INVALID as (phys_cpuid_t)(-1) if it's not defined
by other archs, this will solve the inconsistence in acpi processor driver,
and will prepare for the ACPI on ARM64 for the 64 bit CPU hardware ID
in the following patch.
CC: Rafael J Wysocki <rjw@rjwysocki.net>
Suggested-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Grant Likely <grant.likely@linaro.org>
Acked-by: Sudeep Holla <sudeep.holla@arm.com>
Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
[hj: reworked cpu physid map return codes]
Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
acpi_map_lsapic() will allocate a logical CPU number and map it to
physical CPU id (such as APIC id) for the hot-added CPU, it will also
do some mapping for NUMA node id and etc, acpi_unmap_lsapic() will
do the reverse.
We can see that the name of the function is a little bit confusing and
arch (IA64) dependent so rename them as acpi_(un)map_cpu() to make arch
agnostic and explicit.
Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
apic_id in MADT table is the CPU hardware id which identify
it self in the system for x86 and ia64, OSPM will use it for
SMP init to map APIC ID to logical cpu number in the early
boot, when the DSDT/SSDT (ACPI namespace) is scanned later, the
ACPI processor driver is probed and the driver will use acpi_id
in DSDT to get the apic_id, then map to the logical cpu number
which is needed by the processor driver.
Before ACPI 5.0, only x86 and ia64 were supported in ACPI spec,
so apic_id is used both in arch code and ACPI core which is
pretty fine. Since ACPI 5.0, ARM is supported by ACPI and
APIC is not available on ARM, this will confuse people when
apic_id is both used by x86 and ARM in one function.
So convert apic_id to phys_id (which is the original meaning)
in ACPI processor dirver to make it arch agnostic, but leave the
arch dependent code unchanged, no functional change.
Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Now ARM64 support is being added to ACPI so architecture specific
values can not be used in core ACPI code.
Following on the patch "ACPI / processor: Check if LAPIC is present
during initialization" which uses acpi_lapic in acpi_processor.c,
on ARM64 platform, GIC is used instead of local APIC, so acpi_lapic
is not a suitable value for ARM64.
What is actually important at this point is if there is/are CPU
entry/entries (Local APIC/SAPIC, GICC) in MADT, so introduce
acpi_has_cpu_in_madt() to be arch specific and generic.
Signed-off-by: Graeme Gregory <graeme.gregory@linaro.org>
Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
In acpi_processor_get_info(), ACPI processor info is initialized including
ID, namely CPU index. Currently, on a UP system running an SMP kerenl with
no LAPIC in the MADT, cpu0_initialized is checked to decide whether or not
the CPU has been initialized.
However, this check may not be sufficient for kdump kernels. Most of time
only 1 CPU is supported because of known problems in kdump kernels. So say
the multiple CPUs are present in the boot kernel and a crash happens on
one specific CPU, say CPU2. Then it jumps into the kdump kernel with
"nr_cpus=1" in the command line. In this situation, the kdump kernel
will reuse the ACPI resources from the crashed kernel directly. That
means all LAPIC instances are enabled in the MADT while only one CPU is
in use. In the kdump kernel, x86_cpu_to_apicid contains the correct APIC
ID and it's related to the CPU ID. If cpu0_initialized is checked only, 0
will be used as the CPU index instead of that APIC ID, which is not
correct.
In addition to checking cpu0_initialized, check acpi_lapic. If acpi_lapic
is 0, then no LAPIC is available from the MADT and the system should be
treated as a UP one without a LAPIC (that is, assign 0 to the CPU index).
Otherwise, use the original (valid) CPU index.
Signed-off-by: Baoquan He <bhe@redhat.com>
[rjw: Subject and changelog]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
acpi_processor_add() assumes that present at boot CPUs
are always onlined, it is not so if a CPU failed to become
onlined. As result acpi_processor_add() will mark such CPU
device as onlined in sysfs and following attempts to
online/offline it using /sys/device/system/cpu/cpuX/online
attribute will fail.
Do not poke into device internals in acpi_processor_add()
and touch "struct device { .offline }" attribute, since
for CPUs onlined at boot it's set by:
topology_init() -> arch_register_cpu() -> register_cpu()
before ACPI device tree is parsed, and for hotplugged
CPUs it's set when userspace onlines CPU via sysfs.
Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Acked-by: Toshi Kani <toshi.kani@hp.com>
Cc: 3.11+ <stable@vger.kernel.org> # 3.11+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
According commit d640113fe (ACPI: processor: fix acpi_get_cpuid for UP
processor), BIOS may not provide _MAT or MADT tables and acpi_get_apicid()
always returns -1. For these cases, original code will pass apic_id with
vaule of -1 to acpi_map_cpuid() and it will check the acpi_id. If acpi_id
is equal to zero, ignores apic_id and return zero for CPU0.
Commit b981513 (ACPI / scan: bail out early if failed to parse APIC
ID for CPU) changed the behavior. Return ENODEV when find apic_id is
less than zero after calling acpi_get_apicid(). This causes acpi-cpufreq
driver fails to be loaded on some machines. This patch is to fix it.
Fixes: b981513f80 (ACPI / scan: bail out early if failed to parse APIC ID for CPU)
References: https://bugzilla.kernel.org/show_bug.cgi?id=73781
Cc: 3.14+ <stable@vger.kernel.org> # 3.14+
Reported-and-tested-by: KATO Hiroshi <katoh@mikage.ne.jp>
Reported-and-tested-by: Stuart Foster <smf.linux@ntlworld.com>
Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
* acpi-processor:
ACPI / scan: reduce log level of "ACPI: \_PR_.CPU4: failed to get CPU APIC ID"
ACPI / processor: Return specific error value when mapping lapic id
* acpi-hotplug:
ACPI / scan: Clear match_driver flag in acpi_bus_trim()
* acpi-init:
ACPI / init: Flag use of ACPI and ACPI idioms for power supplies to regulator API
* acpi-pm:
ACPI / PM: Use ACPI_COMPANION() to get ACPI companions of devices
* acpica:
ACPICA: Remove bool usage from ACPICA.
Commit b981513f80 (ACPI / scan: bail out early if failed to parse
APIC ID for CPU) emits an error message if ACPI processor driver fails
to query APIC ID for the CPU.
Originally it's designed to catch BIOS bugs for CPU hot-addition. But
it accidently reveals another type of BIOS bug that:
1) BIOS implements ACPI objects for all possible instead of present
CPUs. (It's valid to do that per ACPI specification.)
2) BIOS doesn't implement the _STA method for CPU objects. OSPM assumes
that all CPU objects are present and functioning and attempts to
use those CPU objects for CPU enumeration, which then triggers the
error message. According to ACPI spec, BIOS should implement _STA
for those absent CPUs at least.
Though it's a BIOS bug in essential, there are some BIOSes in the fields
which are implmented in this way. So reduce the log level from ERR to
DEBUG to accommodate these existing BIOSes.
Fixes: b981513f80 (ACPI / scan: bail out early if failed to parse APIC ID for CPU)
Reported-and-tested-by: Jörg Otte <jrg.otte@gmail.com>
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
[rjw: Changelog]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
* acpi-gpe:
ACPI / EC: disable GPE before removing GPE handler
ACPI / Button: Fix enabling button GPEs twice
* acpi-video:
ACPI: Blacklist Win8 OSI for some HP laptop 2013 models
ACPI / video: Fix typo in video_detect.c
* acpi-thermal:
ACPI / thermal: remove const from thermal_zone_device_ops declaration
* acpi-processor:
ACPI / scan: bail out early if failed to parse APIC ID for CPU
* acpi-sleep:
ACPI / sleep: remove panic in case hardware has changed after S4
Enhance ACPI CPU hotplug driver to print clear error message and
bail out early if BIOS returns wrong value in ACPI MADT table or
_MAT method. Otherwise it will add the CPU device even if failed
to get APIC ID and fails any operations against sysfs interface:
/sys/devices/system/cpu/cpux/online
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
There is no reason to pass an ACPI handle to acpi_bind_one() instead
of a struct acpi_device pointer to the target device object, so
modify that function to take a struct acpi_device pointer as its
second argument and update all code depending on it accordingly.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Lan Tianyu <tianyu.lan@intel.com> # for USB/ACPI
acpi_get_processor_id() can be find nowhere, and the acpi id
is synchronized to APIC id when acpi_get_cpuid() is called, so
the comments can be removed.
Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
acpi_processor_errata() is only called in acpi_processor_get_info(),
and the argument 'pr' passed to acpi_processor_errata() will never be
NULL, so the if (!pr) check is unnecessary and can be removed.
Since the 'pr' argument is not used by acpi_processor_errata() any more,
so change the argument into void too.
Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
errata.smp is used by nowhere, so the variable assignment is meanless,
remove it.
Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Since APIC id is saved in processor struct, just use it and
remove the duplicated _MAT evaluation.
Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
For cpu hot add, we evaluate _MAT or parse MADT twice to get APIC id,
here is the code logic:
acpi_processor_add()
acpi_processor_get_info()
acpi_get_cpuid() will evaluate _MAT or parse MADT;
acpi_processor_hotadd_init()
acpi_map_lsapic() will evaluate _MAT again;
This can be done more effectively, this patch introduces apic_id in struct
processor to save parsed APIC id, and then we can use it and remove the
duplicated _MAT evaluation.
Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
acpi_evaluate_integer() is an ACPI API introduced to evaluate an
ACPI control method that is known to have an integer return value.
This API can simplify the code because the calling function does not need to
use the specified acpi_buffer structure required by acpi_evaluate_object();
Convert acpi_evaluate_object() to acpi_evaluate_integer()
in drivers/acpi/acpi_processor.c in this patch.
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
CPU system maps are protected with reader/writer locks. The reader
lock, get_online_cpus(), assures that the maps are not updated while
holding the lock. The writer lock, cpu_hotplug_begin(), is used to
udpate the cpu maps along with cpu_maps_update_begin().
However, the ACPI processor handler updates the cpu maps without
holding the the writer lock.
acpi_map_lsapic() is called from acpi_processor_hotadd_init() to
update cpu_possible_mask and cpu_present_mask. acpi_unmap_lsapic()
is called from acpi_processor_remove() to update cpu_possible_mask.
Currently, they are either unprotected or protected with the reader
lock, which is not correct.
For example, the get_online_cpus() below is supposed to assure that
cpu_possible_mask is not changed while the code is iterating with
for_each_possible_cpu().
get_online_cpus();
for_each_possible_cpu(cpu) {
:
}
put_online_cpus();
However, this lock has no protection with CPU hotplug since the ACPI
processor handler does not use the writer lock when it updates
cpu_possible_mask. The reader lock does not serialize within the
readers.
This patch protects them with the writer lock with cpu_hotplug_begin()
along with cpu_maps_update_begin(), which must be held before calling
cpu_hotplug_begin(). It also protects arch_register_cpu() /
arch_unregister_cpu(), which creates / deletes a sysfs cpu device
interface. For this purpose it changes cpu_hotplug_begin() and
cpu_hotplug_done() to global and exports them in cpu.h.
Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
try_offline_node() checks that all CPUs associated with the given
node have been removed by using cpu_present_bits. If all cpus
related to that node have been removed, try_offline_node() clears
the node information.
However, try_offline_node() called from acpi_processor_remove() never
clears the node information. For disabling cpu_present_bits,
acpi_unmap_lsapic() needs be called. Yet, acpi_unmap_lsapic() is
called after try_offline_node() has run. So when try_offline_node()
runs, the CPU's cpu_present_bits is always set.
Fix the issue by moving try_offline_node() after acpi_unmap_lsapic().
The problem fixed here was uncovered by commit cecdb19 "ACPI / scan:
Change the implementation of acpi_bus_trim()".
[rjw: Changelog]
Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Acked-by: Toshi Kani <toshi.kani@hp.com>
Cc: 3.9+ <stable@vger.kernel.org> # 3.9+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The __cpuinit type of throwaway sections might have made sense
some time ago when RAM was more constrained, but now the savings
do not offset the cost and complications. For example, the fix in
commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time")
is a good example of the nasty type of bugs that can be created
with improper use of the various __init prefixes.
After a discussion on LKML[1] it was decided that cpuinit should go
the way of devinit and be phased out. Once all the users are gone,
we can then finally remove the macros themselves from linux/init.h.
This removes all the drivers/acpi uses of the __cpuinit macros
from all C files.
[1] https://lkml.org/lkml/2013/5/20/589
Cc: Len Brown <lenb@kernel.org>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: linux-acpi@vger.kernel.org
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
In acpi_processor_add(), get_cpu_device() may return NULL in some cases
which is then passed to acpi_bind_one() and that will case a NULL
pointer dereference to occur.
Add a check to prevent that from happening.
[rjw: Changelog]
Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Make acpi_processor_add() pass the ACPI handle of the processor
namespace object to acpi_bind_one() instead of setting it directly
to allow acpi_bind_one() to catch possible bugs causing the ACPI
handle of the processor device to be set earlier.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Toshi Kani <toshi.kani@hp.com>
Commit ac212b6 (ACPI / processor: Use common hotplug infrastructure)
forgot about initializing the per-CPU 'processors' variables which
lead to ACPI cpuidle failure to use C-states and caused boot slowdown
on multi-CPU machines.
Fix the problem by adding per_cpu(processors, pr->id) initialization
to acpi_processor_add() and add make acpi_processor_remove() clean it
up as appropriate.
Also modify acpi_processor_stop() so that it doesn't clear
per_cpu(processors, pr->id) on processor driver removal which would
then cause problems to happen when the driver is loaded again.
This version of the patch contains fixes from Yinghai Lu.
Reported-and-tested-by: Yinghai Lu <yinghai@kernel.org>
Reported-and-tested-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Split the ACPI processor driver into two parts, one that is
non-modular, resides in the ACPI core and handles the enumeration
and hotplug of processors and one that implements the rest of the
existing processor driver functionality.
The non-modular part uses an ACPI scan handler object to enumerate
processors on the basis of information provided by the ACPI namespace
and to hook up with the common ACPI hotplug infrastructure. It also
populates the ACPI handle of each processor device having a
corresponding object in the ACPI namespace, which allows the driver
proper to bind to those devices, and makes the driver bind to them
if it is readily available (i.e. loaded) when the scan handler's
.attach() routine is running.
There are a few reasons to make this change.
First, switching the ACPI processor driver to using the common ACPI
hotplug infrastructure reduces code duplication and size considerably,
even though a new file is created along with a header comment etc.
Second, since the common hotplug code attempts to offline devices
before starting the (non-reversible) removal procedure, it will abort
(and possibly roll back) hot-remove operations involving processors
if cpu_down() returns an error code for one of them instead of
continuing them blindly (if /sys/firmware/acpi/hotplug/force_remove
is unset). That is a more desirable behavior than what the current
code does.
Finally, the separation of the scan/hotplug part from the driver
proper makes it possible to simplify the driver's .remove() routine,
because it doesn't need to worry about the possible cleanup related
to processor removal any more (the scan/hotplug part is responsible
for that now) and can handle device removal and driver removal
symmetricaly (i.e. as appropriate).
Some user-visible changes in sysfs are made (for example, the
'sysdev' link from the ACPI device node to the processor device's
directory is gone and a 'physical_node' link is present instead
and a corresponding 'firmware_node' is present in the processor
device's directory, the processor driver is now visible under
/sys/bus/cpu/drivers/ and bound to the processor device), but
that shouldn't affect the functionality that users care about
(frequency scaling, C-states and thermal management).
Tested on my venerable Toshiba Portege R500.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Toshi Kani <toshi.kani@hp.com>
Rafael J. Wysocki