FreeBSD Man Pages

acpi(4)

NAME

     acpi -- Advanced Configuration and Power Management support

SYNOPSIS

     device acpi

     options ACPI_DEBUG

DESCRIPTION

     The acpi driver provides support for the Intel/Microsoft/Compaq/Toshiba
     ACPI standard.  This support includes platform hardware discovery (super-
     seding the PnP and PCI BIOS), as well as power management (superseding
     APM) and other features.  ACPI core support is provided by the ACPI CA
     reference implementation from Intel.

     Note that the acpi driver is automatically loaded by the loader(8), and
     should only be compiled into the kernel on platforms where ACPI is manda-
     tory.

SYSCTLS

     The acpi driver is intended to provide power management without user
     intervention.  Thus, some of these sysctls are controlled automatically
     by the power_profile rc(8) script, which can be configured via
     rc.conf(5).  If values are specified manually, they may be overridden.

     hw.acpi.cpu.cx_usage
	     Debugging information listing the percent of total usage for each
	     sleep state.  The values are reset when hw.acpi.cpu.cx_lowest is
	     modified.

     hw.acpi.cpu.cx_lowest
	     Lowest Cx state to use for idling the CPU.  A scheduling algo-
	     rithm will select states between C1 and this setting as system
	     load dictates.  To enable ACPI CPU idling control,
	     machdep.cpu_idle_hlt must be set to 1.

     hw.acpi.cpu.cx_supported
	     List of supported CPU idle states and their transition latency in
	     microseconds.  Each state has a type (e.g., C2).  C1 is equiva-
	     lent to the ia32 HLT instruction, C2 provides a deeper sleep with
	     the same semantics, and C3 provides the deepest sleep but addi-
	     tionally requires bus mastering to be disabled.  States greater
	     than C3 provide even more power savings with the same semantics
	     as the C3 state.  Deeper sleeps provide more power savings but
	     increased transition latency when an interrupt occurs.

TUNABLES

     Tunables can be set at the loader(8) prompt before booting the kernel or
     stored in /boot/loader.conf.

     acpi_dsdt_load
	     Enables loading of a custom ACPI DSDT.

     acpi_dsdt_name
	     Name of the DSDT table to load, if loading is enabled.

     debug.acpi.disabled
	     Override any automatic quirks completely.

     hint.acpi.0.disabled
	     Set this to 1 to disable all of ACPI.  If ACPI has been disabled
	     on your system due to a blacklist entry for your BIOS, you can
	     set this to 0 to re-enable ACPI for testing.

     hw.acpi.ec.poll_timeout
	     Delay in milliseconds to wait for the EC to respond.  Try
	     increasing this number if you get the error
	     "AE_NO_HARDWARE_RESPONSE".

     hw.acpi.host_mem_start
	     Override the assumed memory starting address for PCI host
	     bridges.

     hw.acpi.pci.link.%d.%d.%d.irq
	     Override the interrupt to use.

     hw.acpi.reset_video
	     Enables calling the VESA reset BIOS vector on the resume path.
	     Some graphic chips have problems such as LCD white-out after
	     resume.  Try setting this to 0 if this causes problems for you.

     hw.acpi.serialize_methods
	     Allow override of whether methods execute in parallel or not.
	     Enable this for serial behavior, which fixes "AE_ALREADY_EXISTS"
	     errors for AML that really cannot handle parallel method execu-
	     tion.  It is off by default since this breaks recursive methods
	     and some IBMs use such code.

     hw.acpi.verbose
	     Turn on verbose debugging information about what ACPI is doing.

DISABLING ACPI

     Since ACPI support on different platforms varies greatly, there are many
     debugging and tuning options available.

     For machines known not to work with acpi enabled, there is a BIOS black-
     list.  Currently, the blacklist only controls whether acpi should be dis-
     abled or not.  In the future, it will have more granularity to control
     features (the infrastructure for that is already there).

     To enable acpi (for debugging purposes, etc.) on machines that are on the
     blacklist, set the kernel environment variable hint.acpi.0.disabled to 0.
     Before trying this, consider updating your BIOS to a more recent version
     that may be compatible with ACPI.

     To disable the acpi driver completely, set the kernel environment vari-
     able hint.acpi.0.disabled to 1.

     Some i386 machines totally fail to operate with some or all of ACPI dis-
     abled.  Other i386 machines fail with ACPI enabled.  Disabling all or
     part of ACPI on non-i386 platforms (i.e., platforms where ACPI support is
     mandatory) may result in a non-functional system.

     The acpi driver comprises a set of drivers, which may be selectively dis-
     abled in case of problems.  To disable a sub-driver, list it in the ker-

     bus	  (feature) Probes and attaches subdevices.  Disabling will
		  avoid scanning the ACPI namespace entirely.

     children	  (feature) Attaches standard ACPI sub-drivers and devices
		  enumerated in the ACPI namespace.  Disabling this has a sim-
		  ilar effect to disabling ``bus'', except that the ACPI
		  namespace will still be scanned.

     button	  (device) Supports ACPI button devices (typically power and
		  sleep buttons).

     cmbat	  (device) Control-method batteries device.

     cpu	  (device) Supports CPU power-saving and speed-setting func-
		  tions.

     ec 	  (device) Supports the ACPI Embedded Controller interface,
		  used to communicate with embedded platform controllers.

     isa	  (device) Supports an ISA bus bridge defined in the ACPI
		  namespace, typically as a child of a PCI bus.

     lid	  (device) Supports an ACPI laptop lid switch, which typically
		  puts a system to sleep.

     quirks	  (feature) Do not honor quirks.  Quirks automatically disable
		  ACPI functionality based on the XSDT table's OEM vendor name
		  and revision date.

     pci	  (device) Supports Host to PCI bridges.

     pci_link	  (feature) Performs PCI interrupt routing.

     sysresource  (device) Pseudo-devices containing resources which ACPI
		  claims.

     thermal	  (device) Supports system cooling and heat management.

     timer	  (device) Implements a timecounter using the ACPI fixed-fre-
		  quency timer.

     video	  (device) Supports acpi_video which may conflict with agp
		  device.

     It is also possible to avoid portions of the ACPI namespace which may be
     causing problems, by listing the full path of the root of the region to
     be avoided in the kernel environment variable debug.acpi.avoid.  The
     object and all of its children will be ignored during the bus/children
     scan of the namespace.  The ACPI CA code will still know about the
     avoided region.

DEBUGGING OUTPUT

     To enable debugging output, acpi must be compiled with options
     ACPI_DEBUG.  Debugging output is separated between layers and levels,
     where a layer is a component of the ACPI subsystem, and a level is a par-
     ticular kind of debugging output.

     ACPI_UTILITIES	   Utility ("ut") functions
     ACPI_HARDWARE	   Hardware access ("hw")
     ACPI_EVENTS	   Event and GPE ("ev")
     ACPI_TABLES	   Table access ("tb")
     ACPI_NAMESPACE	   Namespace evaluation ("ns")
     ACPI_PARSER	   AML parser ("ps")
     ACPI_DISPATCHER	   Internal representation of interpreter state ("ds")
     ACPI_EXECUTER	   Execute AML methods ("ex")
     ACPI_RESOURCES	   Resource parsing ("rs")
     ACPI_CA_DEBUGGER	   Debugger implementation ("db", "dm")
     ACPI_OS_SERVICES	   Usermode support routines ("os")
     ACPI_CA_DISASSEMBLER  Disassembler implementation (unused)
     ACPI_ALL_COMPONENTS   All the above ACPI-CA components
     ACPI_AC_ADAPTER	   AC adapter driver
     ACPI_BATTERY	   Control-method battery driver
     ACPI_BUS		   ACPI, ISA, and PCI bus drivers
     ACPI_BUTTON	   Power and sleep button driver
     ACPI_EC		   Embedded controller driver
     ACPI_FAN		   Fan driver
     ACPI_OEM		   Platform-specific driver for hotkeys, LED, etc.
     ACPI_POWER 	   Power resource driver
     ACPI_PROCESSOR	   CPU driver
     ACPI_THERMAL	   Thermal zone driver
     ACPI_TIMER 	   Timer driver
     ACPI_ALL_DRIVERS	   All the above FreeBSD ACPI drivers

     The supported levels are:

     ACPI_LV_ERROR	      Fatal error conditions
     ACPI_LV_WARN	      Warnings and potential problems
     ACPI_LV_INIT	      Initialization progress
     ACPI_LV_DEBUG_OBJECT     Stores to objects
     ACPI_LV_INFO	      General information and progress
     ACPI_LV_ALL_EXCEPTIONS   All the previous levels
     ACPI_LV_INIT_NAMES
     ACPI_LV_PARSE
     ACPI_LV_LOAD
     ACPI_LV_DISPATCH
     ACPI_LV_EXEC
     ACPI_LV_NAMES
     ACPI_LV_OPREGION
     ACPI_LV_BFIELD
     ACPI_LV_TABLES
     ACPI_LV_VALUES
     ACPI_LV_OBJECTS
     ACPI_LV_RESOURCES
     ACPI_LV_USER_REQUESTS
     ACPI_LV_PACKAGE
     ACPI_LV_VERBOSITY1       All the previous levels
     ACPI_LV_ALLOCATIONS
     ACPI_LV_FUNCTIONS
     ACPI_LV_OPTIMIZATIONS
     ACPI_LV_VERBOSITY2
     ACPI_LV_ALL
     ACPI_LV_MUTEX
     ACPI_LV_THREADS
     ACPI_LV_IO
     ACPI_LV_INTERRUPTS
     massive amounts of debugging output.  For example, the following configu-
     ration is a good way to gather initial information.  It enables debug
     output for both ACPI-CA and the acpi driver, printing basic information
     about errors, warnings, and progress.

	   debug.acpi.layer="ACPI_ALL_COMPONENTS ACPI_ALL_DRIVERS"
	   debug.acpi.level="ACPI_LV_ALL_EXCEPTIONS"

     Debugging output by the ACPI CA subsystem is prefixed with the module
     name in lowercase, followed by a source line number.  Output from the
     FreeBSD-local code follows the same format, but the module name is upper-
     cased.

OVERRIDING YOUR BIOS BYTECODE

     ACPI interprets bytecode named AML (ACPI Machine Language) provided by
     the BIOS vendor as a memory image at boot time.  Sometimes, the AML code
     contains a bug that does not appear when parsed by the Microsoft imple-
     mentation.  FreeBSD provides a way to override it with your own AML code
     to work around or debug such problems.  Note that all AML in your DSDT
     and any SSDT tables is overridden.

     In order to load your AML code, you must edit /boot/loader.conf and
     include the following lines.

	   acpi_dsdt_load="YES"
	   acpi_dsdt_name="/boot/acpi_dsdt.aml" # You may change this name.

     In order to prepare your AML code, you will need the acpidump(8) and
     iasl(8) utilities and some ACPI knowledge.

COMPATIBILITY

     ACPI is only found and supported on i386/ia32, ia64, and amd64.

SEE ALSO

     kenv(1), acpi_thermal(4), device.hints(5), loader.conf(5), acpiconf(8),
     acpidump(8), config(8), iasl(8)

     Compaq Computer Corporation, Intel Corporation, Microsoft Corporation,
     Phoenix Technologies Ltd., and Toshiba Corporation, Advanced
     Configuration and Power Interface Specification, August 25, 2003,
     http://acpi.info/spec.htm.

AUTHORS

     The ACPI CA subsystem is developed and maintained by Intel Architecture
     Labs.

     The following people made notable contributions to the ACPI subsystem in
     FreeBSD: Michael Smith, Takanori Watanabe <takawata@jp.FreeBSD.org>,
     Mitsuru IWASAKI <iwasaki@jp.FreeBSD.org>, Munehiro Matsuda, Nate Lawson,
     the ACPI-jp mailing list at <acpi-jp@jp.FreeBSD.org>, and many other con-
     tributors.

     This manual page was written by Michael Smith <msmith@FreeBSD.org>.

BUGS

     If the acpi driver is loaded as a module when it is already linked as
     part of the kernel, odd things may happen.

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