mirror of
https://github.com/torvalds/linux.git
synced 2024-11-22 04:38:03 +00:00
a6021aa24f
The embedded controller code is mainly used on x86 laptops and cannot work without PC style I/O port access. Make this a user-visible configuration option that is default enabled on x86 but otherwise disabled, and that can never be enabled unless CONFIG_HAS_IOPORT is also available. The empty stubs in internal.h help ignore the EC code in configurations that don't support it. In order to see those stubs, the sbshc code also has to include this header and drop duplicate declarations. All the direct callers of ec_read/ec_write already had an x86 dependency and now also need to depend on APCI_EC. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Guenter Roeck <linux@roeck-us.net> Acked-by: Hans de Goede <hdegoede@redhat.com> Link: https://patch.msgid.link/20241011061948.3211423-1-arnd@kernel.org [ rjw: Subject edits ] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
616 lines
19 KiB
Plaintext
616 lines
19 KiB
Plaintext
# SPDX-License-Identifier: GPL-2.0
|
|
#
|
|
# ACPI Configuration
|
|
#
|
|
|
|
config ARCH_SUPPORTS_ACPI
|
|
bool
|
|
|
|
menuconfig ACPI
|
|
bool "ACPI (Advanced Configuration and Power Interface) Support"
|
|
depends on ARCH_SUPPORTS_ACPI
|
|
select PNP
|
|
select NLS
|
|
select CRC32
|
|
select FIRMWARE_TABLE
|
|
default y if X86
|
|
help
|
|
Advanced Configuration and Power Interface (ACPI) support for
|
|
Linux requires an ACPI-compliant platform (hardware/firmware),
|
|
and assumes the presence of OS-directed configuration and power
|
|
management (OSPM) software. This option will enlarge your
|
|
kernel by about 70K.
|
|
|
|
Linux ACPI provides a robust functional replacement for several
|
|
legacy configuration and power management interfaces, including
|
|
the Plug-and-Play BIOS specification (PnP BIOS), the
|
|
MultiProcessor Specification (MPS), and the Advanced Power
|
|
Management (APM) specification. If both ACPI and APM support
|
|
are configured, ACPI is used.
|
|
|
|
Linux support for ACPI is based on Intel Corporation's ACPI
|
|
Component Architecture (ACPI CA). For more information on the
|
|
ACPI CA, see:
|
|
<https://acpica.org/>
|
|
|
|
ACPI is an open industry specification originally co-developed by
|
|
Hewlett-Packard, Intel, Microsoft, Phoenix, and Toshiba. Currently,
|
|
it is developed by the ACPI Specification Working Group (ASWG) under
|
|
the UEFI Forum and any UEFI member can join the ASWG and contribute
|
|
to the ACPI specification.
|
|
The specification is available at:
|
|
<https://uefi.org/specifications>
|
|
|
|
if ACPI
|
|
|
|
config ACPI_LEGACY_TABLES_LOOKUP
|
|
bool
|
|
|
|
config ARCH_MIGHT_HAVE_ACPI_PDC
|
|
bool
|
|
|
|
config ACPI_GENERIC_GSI
|
|
bool
|
|
|
|
config ACPI_SYSTEM_POWER_STATES_SUPPORT
|
|
bool
|
|
|
|
config ACPI_CCA_REQUIRED
|
|
bool
|
|
|
|
config ACPI_TABLE_LIB
|
|
bool
|
|
|
|
config ACPI_THERMAL_LIB
|
|
depends on THERMAL
|
|
bool
|
|
|
|
config ACPI_DEBUGGER
|
|
bool "AML debugger interface"
|
|
select ACPI_DEBUG
|
|
help
|
|
Enable in-kernel debugging of AML facilities: statistics,
|
|
internal object dump, single step control method execution.
|
|
This is still under development, currently enabling this only
|
|
results in the compilation of the ACPICA debugger files.
|
|
|
|
if ACPI_DEBUGGER
|
|
|
|
config ACPI_DEBUGGER_USER
|
|
tristate "Userspace debugger accessibility"
|
|
depends on DEBUG_FS
|
|
help
|
|
Export /sys/kernel/debug/acpi/acpidbg for userspace utilities
|
|
to access the debugger functionalities.
|
|
|
|
endif
|
|
|
|
config ACPI_SPCR_TABLE
|
|
bool "ACPI Serial Port Console Redirection Support"
|
|
default y if X86
|
|
help
|
|
Enable support for Serial Port Console Redirection (SPCR) Table.
|
|
This table provides information about the configuration of the
|
|
earlycon console.
|
|
|
|
config ACPI_FPDT
|
|
bool "ACPI Firmware Performance Data Table (FPDT) support"
|
|
depends on X86_64 || ARM64
|
|
help
|
|
Enable support for the Firmware Performance Data Table (FPDT).
|
|
This table provides information on the timing of the system
|
|
boot, S3 suspend and S3 resume firmware code paths.
|
|
|
|
config ACPI_LPIT
|
|
bool
|
|
depends on X86_64
|
|
default y
|
|
|
|
config ACPI_SLEEP
|
|
bool
|
|
depends on SUSPEND || HIBERNATION
|
|
depends on ACPI_SYSTEM_POWER_STATES_SUPPORT
|
|
default y
|
|
|
|
config ACPI_REV_OVERRIDE_POSSIBLE
|
|
bool "Allow supported ACPI revision to be overridden"
|
|
depends on X86
|
|
default y
|
|
help
|
|
The platform firmware on some systems expects Linux to return "5" as
|
|
the supported ACPI revision which makes it expose system configuration
|
|
information in a special way.
|
|
|
|
For example, based on what ACPI exports as the supported revision,
|
|
Dell XPS 13 (2015) configures its audio device to either work in HDA
|
|
mode or in I2S mode, where the former is supposed to be used on Linux
|
|
until the latter is fully supported (in the kernel as well as in user
|
|
space).
|
|
|
|
This option enables a DMI-based quirk for the above Dell machine (so
|
|
that HDA audio is exposed by the platform firmware to the kernel) and
|
|
makes it possible to force the kernel to return "5" as the supported
|
|
ACPI revision via the "acpi_rev_override" command line switch.
|
|
|
|
config ACPI_EC
|
|
bool "Embedded Controller"
|
|
depends on HAS_IOPORT
|
|
default X86
|
|
help
|
|
This driver handles communication with the microcontroller
|
|
on many x86 laptops and other machines.
|
|
|
|
config ACPI_EC_DEBUGFS
|
|
tristate "EC read/write access through /sys/kernel/debug/ec"
|
|
depends on ACPI_EC
|
|
help
|
|
Say N to disable Embedded Controller /sys/kernel/debug interface
|
|
|
|
Be aware that using this interface can confuse your Embedded
|
|
Controller in a way that a normal reboot is not enough. You then
|
|
have to power off your system, and remove the laptop battery for
|
|
some seconds.
|
|
An Embedded Controller typically is available on laptops and reads
|
|
sensor values like battery state and temperature.
|
|
The kernel accesses the EC through ACPI parsed code provided by BIOS
|
|
tables. This option allows to access the EC directly without ACPI
|
|
code being involved.
|
|
Thus this option is a debug option that helps to write ACPI drivers
|
|
and can be used to identify ACPI code or EC firmware bugs.
|
|
|
|
config ACPI_AC
|
|
tristate "AC Adapter"
|
|
select POWER_SUPPLY
|
|
default y
|
|
help
|
|
This driver supports the AC Adapter object, which indicates
|
|
whether a system is on AC or not. If you have a system that can
|
|
switch between A/C and battery, say Y.
|
|
|
|
To compile this driver as a module, choose M here:
|
|
the module will be called ac.
|
|
|
|
config ACPI_BATTERY
|
|
tristate "Battery"
|
|
select POWER_SUPPLY
|
|
default y
|
|
help
|
|
This driver adds support for battery information through
|
|
/proc/acpi/battery. If you have a mobile system with a battery,
|
|
say Y.
|
|
|
|
To compile this driver as a module, choose M here:
|
|
the module will be called battery.
|
|
|
|
config ACPI_BUTTON
|
|
tristate "Button"
|
|
depends on INPUT
|
|
default y
|
|
help
|
|
This driver handles events on the power, sleep, and lid buttons.
|
|
A daemon reads events from input devices or via netlink and
|
|
performs user-defined actions such as shutting down the system.
|
|
This is necessary for software-controlled poweroff.
|
|
|
|
To compile this driver as a module, choose M here:
|
|
the module will be called button.
|
|
|
|
config ACPI_TINY_POWER_BUTTON
|
|
tristate "Tiny Power Button Driver"
|
|
depends on !ACPI_BUTTON
|
|
help
|
|
This driver provides a tiny alternative to the ACPI Button driver.
|
|
The tiny power button driver only handles the power button. Rather
|
|
than notifying userspace via the input layer or a netlink event, this
|
|
driver directly signals the init process to shut down.
|
|
|
|
This driver is particularly suitable for cloud and VM environments,
|
|
which use a simulated power button to initiate a controlled poweroff,
|
|
but which may not want to run a separate userspace daemon to process
|
|
input events.
|
|
|
|
config ACPI_TINY_POWER_BUTTON_SIGNAL
|
|
int "Tiny Power Button Signal"
|
|
depends on ACPI_TINY_POWER_BUTTON
|
|
default 38
|
|
help
|
|
Default signal to send to init in response to the power button.
|
|
|
|
Likely values here include 38 (SIGRTMIN+4) to power off, or 2
|
|
(SIGINT) to simulate Ctrl+Alt+Del.
|
|
|
|
config ACPI_VIDEO
|
|
tristate "Video"
|
|
depends on BACKLIGHT_CLASS_DEVICE
|
|
depends on INPUT
|
|
depends on ACPI_WMI || !X86
|
|
select THERMAL
|
|
help
|
|
This driver implements the ACPI Extensions For Display Adapters
|
|
for integrated graphics devices on motherboard, as specified in
|
|
ACPI 2.0 Specification, Appendix B. This supports basic operations
|
|
such as defining the video POST device, retrieving EDID information,
|
|
and setting up a video output.
|
|
|
|
To compile this driver as a module, choose M here:
|
|
the module will be called video.
|
|
|
|
config ACPI_FAN
|
|
tristate "Fan"
|
|
depends on THERMAL
|
|
default y
|
|
help
|
|
This driver supports ACPI fan devices, allowing user-mode
|
|
applications to perform basic fan control (on, off, status).
|
|
|
|
To compile this driver as a module, choose M here:
|
|
the module will be called fan.
|
|
|
|
config ACPI_TAD
|
|
tristate "ACPI Time and Alarm (TAD) Device Support"
|
|
depends on SYSFS && PM_SLEEP
|
|
help
|
|
The ACPI Time and Alarm (TAD) device is an alternative to the Real
|
|
Time Clock (RTC). Its wake timers allow the system to transition from
|
|
the S3 (or optionally S4/S5) state to S0 state after a time period
|
|
elapses. In comparison with the RTC Alarm, the TAD provides a larger
|
|
scale of flexibility in the wake timers. The time capabilities of the
|
|
TAD maintain the time of day information across platform power
|
|
transitions, and keep track of time even when the platform is turned
|
|
off.
|
|
|
|
config ACPI_DOCK
|
|
bool "Dock"
|
|
help
|
|
This driver supports ACPI-controlled docking stations and removable
|
|
drive bays such as the IBM Ultrabay and the Dell Module Bay.
|
|
|
|
config ACPI_CPU_FREQ_PSS
|
|
bool
|
|
|
|
config ACPI_PROCESSOR_CSTATE
|
|
def_bool y
|
|
depends on ACPI_PROCESSOR
|
|
depends on X86
|
|
|
|
config ACPI_PROCESSOR_IDLE
|
|
bool
|
|
select CPU_IDLE
|
|
|
|
config ACPI_MCFG
|
|
bool
|
|
|
|
config ACPI_CPPC_LIB
|
|
bool
|
|
depends on ACPI_PROCESSOR
|
|
select MAILBOX
|
|
select PCC
|
|
help
|
|
If this option is enabled, this file implements common functionality
|
|
to parse CPPC tables as described in the ACPI 5.1+ spec. The
|
|
routines implemented are meant to be used by other
|
|
drivers to control CPU performance using CPPC semantics.
|
|
If your platform does not support CPPC in firmware,
|
|
leave this option disabled.
|
|
|
|
config ACPI_PROCESSOR
|
|
tristate "Processor"
|
|
depends on X86 || ARM64 || LOONGARCH || RISCV
|
|
select ACPI_PROCESSOR_IDLE
|
|
select ACPI_CPU_FREQ_PSS if X86 || LOONGARCH
|
|
select THERMAL
|
|
default y
|
|
help
|
|
This driver adds support for the ACPI Processor package. It is required
|
|
by several flavors of cpufreq performance-state, thermal, throttling and
|
|
idle drivers.
|
|
|
|
To compile this driver as a module, choose M here:
|
|
the module will be called processor.
|
|
|
|
config ACPI_IPMI
|
|
tristate "IPMI"
|
|
depends on IPMI_HANDLER
|
|
help
|
|
This driver enables the ACPI to access the BMC controller. And it
|
|
uses the IPMI request/response message to communicate with BMC
|
|
controller, which can be found on the server.
|
|
|
|
To compile this driver as a module, choose M here:
|
|
the module will be called as acpi_ipmi.
|
|
|
|
config ACPI_HOTPLUG_CPU
|
|
bool
|
|
depends on ACPI_PROCESSOR && HOTPLUG_CPU
|
|
select ACPI_CONTAINER
|
|
|
|
config ACPI_PROCESSOR_AGGREGATOR
|
|
tristate "Processor Aggregator"
|
|
depends on ACPI_PROCESSOR
|
|
depends on X86
|
|
help
|
|
ACPI 4.0 defines processor Aggregator, which enables OS to perform
|
|
specific processor configuration and control that applies to all
|
|
processors in the platform. Currently only logical processor idling
|
|
is defined, which is to reduce power consumption. This driver
|
|
supports the new device.
|
|
|
|
config ACPI_THERMAL
|
|
tristate "Thermal Zone"
|
|
depends on ACPI_PROCESSOR
|
|
select THERMAL
|
|
select ACPI_THERMAL_LIB
|
|
default y
|
|
help
|
|
This driver supports ACPI thermal zones. Most mobile and
|
|
some desktop systems support ACPI thermal zones. It is HIGHLY
|
|
recommended that this option be enabled, as your processor(s)
|
|
may be damaged without it.
|
|
|
|
To compile this driver as a module, choose M here:
|
|
the module will be called thermal.
|
|
|
|
config ACPI_PLATFORM_PROFILE
|
|
tristate
|
|
|
|
config ACPI_CUSTOM_DSDT_FILE
|
|
string "Custom DSDT Table file to include"
|
|
default ""
|
|
depends on !STANDALONE
|
|
help
|
|
This option supports a custom DSDT by linking it into the kernel.
|
|
|
|
Enter the full path name to the file which includes the AmlCode
|
|
or dsdt_aml_code declaration.
|
|
|
|
If unsure, don't enter a file name.
|
|
|
|
config ACPI_CUSTOM_DSDT
|
|
bool
|
|
default ACPI_CUSTOM_DSDT_FILE != ""
|
|
|
|
config ARCH_HAS_ACPI_TABLE_UPGRADE
|
|
def_bool n
|
|
|
|
config ACPI_TABLE_UPGRADE
|
|
bool "Allow upgrading ACPI tables via initrd"
|
|
depends on BLK_DEV_INITRD && ARCH_HAS_ACPI_TABLE_UPGRADE
|
|
default y
|
|
help
|
|
This option provides functionality to upgrade arbitrary ACPI tables
|
|
via initrd. No functional change if no ACPI tables are passed via
|
|
initrd, therefore it's safe to say Y.
|
|
See Documentation/admin-guide/acpi/initrd_table_override.rst for details
|
|
|
|
config ACPI_TABLE_OVERRIDE_VIA_BUILTIN_INITRD
|
|
bool "Override ACPI tables from built-in initrd"
|
|
depends on ACPI_TABLE_UPGRADE
|
|
depends on INITRAMFS_SOURCE!="" && INITRAMFS_COMPRESSION_NONE
|
|
help
|
|
This option provides functionality to override arbitrary ACPI tables
|
|
from built-in uncompressed initrd.
|
|
|
|
See Documentation/admin-guide/acpi/initrd_table_override.rst for details
|
|
|
|
config ACPI_DEBUG
|
|
bool "Debug Statements"
|
|
help
|
|
The ACPI subsystem can produce debug output. Saying Y enables this
|
|
output and increases the kernel size by around 50K.
|
|
|
|
Use the acpi.debug_layer and acpi.debug_level kernel command-line
|
|
parameters documented in Documentation/firmware-guide/acpi/debug.rst and
|
|
Documentation/admin-guide/kernel-parameters.rst to control the type and
|
|
amount of debug output.
|
|
|
|
config ACPI_PCI_SLOT
|
|
bool "PCI slot detection driver"
|
|
depends on SYSFS && PCI
|
|
help
|
|
This driver creates entries in /sys/bus/pci/slots/ for all PCI
|
|
slots in the system. This can help correlate PCI bus addresses,
|
|
i.e., segment/bus/device/function tuples, with physical slots in
|
|
the system. If you are unsure, say N.
|
|
|
|
config ACPI_CONTAINER
|
|
bool "Container and Module Devices"
|
|
default (ACPI_HOTPLUG_MEMORY || ACPI_HOTPLUG_CPU)
|
|
help
|
|
This driver supports ACPI Container and Module devices (IDs
|
|
ACPI0004, PNP0A05, and PNP0A06).
|
|
|
|
This helps support hotplug of nodes, CPUs, and memory.
|
|
|
|
config ACPI_HOTPLUG_MEMORY
|
|
bool "Memory Hotplug"
|
|
depends on MEMORY_HOTPLUG
|
|
help
|
|
This driver supports ACPI memory hotplug. The driver
|
|
fields notifications on ACPI memory devices (PNP0C80),
|
|
which represent memory ranges that may be onlined or
|
|
offlined during runtime.
|
|
|
|
If your hardware and firmware do not support adding or
|
|
removing memory devices at runtime, you need not enable
|
|
this driver.
|
|
|
|
config ACPI_HOTPLUG_IOAPIC
|
|
bool
|
|
depends on PCI
|
|
depends on X86_IO_APIC
|
|
default y
|
|
|
|
config ACPI_SBS
|
|
tristate "Smart Battery System"
|
|
depends on X86 && ACPI_EC
|
|
select POWER_SUPPLY
|
|
help
|
|
This driver supports the Smart Battery System, another
|
|
type of access to battery information, found on some laptops.
|
|
|
|
To compile this driver as a module, choose M here:
|
|
the modules will be called sbs and sbshc.
|
|
|
|
config ACPI_HED
|
|
tristate "Hardware Error Device"
|
|
help
|
|
This driver supports the Hardware Error Device (PNP0C33),
|
|
which is used to report some hardware errors notified via
|
|
SCI, mainly the corrected errors.
|
|
|
|
config ACPI_BGRT
|
|
bool "Boottime Graphics Resource Table support"
|
|
depends on EFI && (X86 || ARM64 || LOONGARCH)
|
|
help
|
|
This driver adds support for exposing the ACPI Boottime Graphics
|
|
Resource Table, which allows the operating system to obtain
|
|
data from the firmware boot splash. It will appear under
|
|
/sys/firmware/acpi/bgrt/ .
|
|
|
|
config ACPI_REDUCED_HARDWARE_ONLY
|
|
bool "Hardware-reduced ACPI support only" if EXPERT
|
|
help
|
|
This config item changes the way the ACPI code is built. When this
|
|
option is selected, the kernel will use a specialized version of
|
|
ACPICA that ONLY supports the ACPI "reduced hardware" mode. The
|
|
resulting kernel will be smaller but it will also be restricted to
|
|
running in ACPI reduced hardware mode ONLY.
|
|
|
|
If you are unsure what to do, do not enable this option.
|
|
|
|
config ACPI_NHLT
|
|
bool
|
|
|
|
source "drivers/acpi/nfit/Kconfig"
|
|
source "drivers/acpi/numa/Kconfig"
|
|
source "drivers/acpi/apei/Kconfig"
|
|
source "drivers/acpi/dptf/Kconfig"
|
|
|
|
config ACPI_WATCHDOG
|
|
bool
|
|
|
|
config ACPI_EXTLOG
|
|
tristate "Extended Error Log support"
|
|
depends on X86_MCE && X86_LOCAL_APIC && EDAC
|
|
select UEFI_CPER
|
|
help
|
|
Certain usages such as Predictive Failure Analysis (PFA) require
|
|
more information about the error than what can be described in
|
|
processor machine check banks. Most server processors log
|
|
additional information about the error in processor uncore
|
|
registers. Since the addresses and layout of these registers vary
|
|
widely from one processor to another, system software cannot
|
|
readily make use of them. To complicate matters further, some of
|
|
the additional error information cannot be constructed without
|
|
detailed knowledge about platform topology.
|
|
|
|
Enhanced MCA Logging allows firmware to provide additional error
|
|
information to system software, synchronous with MCE or CMCI. This
|
|
driver adds support for that functionality with corresponding
|
|
tracepoint which carries that information to userspace.
|
|
|
|
config ACPI_ADXL
|
|
bool
|
|
|
|
config ACPI_CONFIGFS
|
|
tristate "ACPI configfs support"
|
|
select CONFIGFS_FS
|
|
help
|
|
Select this option to enable support for ACPI configuration from
|
|
userspace. The configurable ACPI groups will be visible under
|
|
/config/acpi, assuming configfs is mounted under /config.
|
|
|
|
config ACPI_PFRUT
|
|
tristate "ACPI Platform Firmware Runtime Update and Telemetry"
|
|
depends on 64BIT
|
|
help
|
|
This mechanism allows certain pieces of the platform firmware
|
|
to be updated on the fly while the system is running (runtime)
|
|
without the need to restart it, which is key in the cases when
|
|
the system needs to be available 100% of the time and it cannot
|
|
afford the downtime related to restarting it, or when the work
|
|
carried out by the system is particularly important, so it cannot
|
|
be interrupted, and it is not practical to wait until it is complete.
|
|
|
|
The existing firmware code can be modified (driver update) or
|
|
extended by adding new code to the firmware (code injection).
|
|
|
|
Besides, the telemetry driver allows user space to fetch telemetry
|
|
data from the firmware with the help of the Platform Firmware Runtime
|
|
Telemetry interface.
|
|
|
|
To compile the drivers as modules, choose M here:
|
|
the modules will be called pfr_update and pfr_telemetry.
|
|
|
|
if ARM64
|
|
source "drivers/acpi/arm64/Kconfig"
|
|
endif
|
|
|
|
config ACPI_PPTT
|
|
bool
|
|
|
|
config ACPI_PCC
|
|
bool "ACPI PCC Address Space"
|
|
depends on PCC
|
|
default y
|
|
help
|
|
The PCC Address Space also referred as PCC Operation Region pertains
|
|
to the region of PCC subspace that succeeds the PCC signature.
|
|
|
|
The PCC Operation Region works in conjunction with the PCC Table
|
|
(Platform Communications Channel Table). PCC subspaces that are
|
|
marked for use as PCC Operation Regions must not be used as PCC
|
|
subspaces for the standard ACPI features such as CPPC, RASF, PDTT and
|
|
MPST. These standard features must always use the PCC Table instead.
|
|
|
|
Enable this feature if you want to set up and install the PCC Address
|
|
Space handler to handle PCC OpRegion in the firmware.
|
|
|
|
config ACPI_FFH
|
|
bool "ACPI FFH Address Space"
|
|
default n
|
|
help
|
|
The FFH(Fixed Function Hardware) Address Space also referred as FFH
|
|
Operation Region allows to define platform specific opregion.
|
|
|
|
Enable this feature if you want to set up and install the FFH Address
|
|
Space handler to handle FFH OpRegion in the firmware.
|
|
|
|
source "drivers/acpi/pmic/Kconfig"
|
|
|
|
config ACPI_VIOT
|
|
bool
|
|
|
|
config ACPI_PRMT
|
|
bool "Platform Runtime Mechanism Support"
|
|
depends on EFI_RUNTIME_WRAPPERS && (X86_64 || ARM64)
|
|
default y
|
|
help
|
|
Platform Runtime Mechanism (PRM) is a firmware interface exposing a
|
|
set of binary executables that can be called from the AML interpreter
|
|
or directly from device drivers.
|
|
|
|
Say Y to enable the AML interpreter to execute the PRM code.
|
|
|
|
While this feature is optional in principle, leaving it out may
|
|
substantially increase computational overhead related to the
|
|
initialization of some server systems.
|
|
|
|
endif # ACPI
|
|
|
|
config X86_PM_TIMER
|
|
bool "Power Management Timer Support" if EXPERT
|
|
depends on X86 && (ACPI || JAILHOUSE_GUEST)
|
|
default y
|
|
help
|
|
The Power Management Timer is available on all ACPI-capable,
|
|
in most cases even if ACPI is unusable or blacklisted.
|
|
|
|
This timing source is not affected by power management features
|
|
like aggressive processor idling, throttling, frequency and/or
|
|
voltage scaling, unlike the commonly used Time Stamp Counter
|
|
(TSC) timing source.
|
|
|
|
You should nearly always say Y here because many modern
|
|
systems require this timer.
|