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. The project home page for the Linux ACPI subsystem is here: <https://01.org/linux-acpi> 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>
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.
Export /sys/kernel/debug/acpi/acpidbg for userspace utilities to access the debugger functionalities.
Enable support for Serial Port Console Redirection (SPCR) Table. This table provides information about the configuration of the earlycon console.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
This driver supports ACPI-controlled docking stations and removable drive bays such as the IBM Ultrabay and the Dell Module Bay.
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.
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.
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 on the server. To compile this driver as a module, choose M here: the module will be called as acpi_ipmi.
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.
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.
This option supports a custom DSDT by linking it into the kernel. See Documentation/admin-guide/acpi/dsdt-override.rst 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.
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
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
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.
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.
This driver supports ACPI Container and Module devices (IDs ACPI0004, PNP0A05, and PNP0A06). This helps support hotplug of nodes, CPUs, and memory.
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.
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.
This driver supports the Hardware Error Device (PNP0C33), which is used to report some hardware errors notified via SCI, mainly the corrected errors.
This debug facility allows ACPI AML methods to be inserted and/or replaced without rebooting the system. For details refer to: Documentation/firmware-guide/acpi/method-customizing.rst. NOTE: This option is security sensitive, because it allows arbitrary kernel memory to be written to by root (uid=0) users, allowing them to bypass certain security measures (e.g. if root is not allowed to load additional kernel modules after boot, this feature may be used to override that restriction).
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/ .
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.
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.
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.
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.