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ACPI(4)		       FreeBSD Kernel Interfaces Manual		       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 bootloader, and
     should not	normally be compiled into the kernel.

ENVIRONMENT
     This support is still experimental, and thus there	are many debugging and
     tuning options which are managed via the kernel environment.  Tunables
     can be set	at the loader(8) prompt	before booting the kernel or stored in
     /boot/loader.conf.

     Debugging is separated between layers and levels, where a layer is	a por-
     tion of the ACPI subsystem, and a level is	a particular kind of debugging
     output.

     Both layers and levels are	specified as a whitespace-separated list of
     tokens, with layers listed	in debug.acpi.layer and	levels in
     debug.acpi.level.	The supported layers are:

	   ACPI_UTILITIES
	   ACPI_HARDWARE
	   ACPI_EVENTS
	   ACPI_TABLES
	   ACPI_NAMESPACE
	   ACPI_PARSER
	   ACPI_DISPATCHER
	   ACPI_EXECUTER
	   ACPI_RESOURCES
	   ACPI_CA_DEBUGGER
	   ACPI_OS_SERVICES
	   ACPI_CA_DISASSEMBLER
	   ACPI_ALL_COMPONENTS
	   ACPI_AC_ADAPTER
	   ACPI_BATTERY
	   ACPI_BUS
	   ACPI_BUTTON
	   ACPI_EC
	   ACPI_FAN
	   ACPI_POWER
	   ACPI_PROCESSOR
	   ACPI_THERMAL
	   ACPI_TIMER
	   ACPI_ALL_DRIVERS

     The supported levels are:

	   ACPI_LV_ERROR
	   ACPI_LV_WARN
	   ACPI_LV_INIT
	   ACPI_LV_DEBUG_OBJECT
	   ACPI_LV_INFO
	   ACPI_LV_ALL_EXCEPTIONS
	   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
	   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
	   ACPI_LV_VERBOSITY3
	   ACPI_LV_AML_DISASSEMBLE
	   ACPI_LV_VERBOSE_INFO
	   ACPI_LV_FULL_TABLES
	   ACPI_LV_EVENTS
	   ACPI_LV_VERBOSE

     Selection of the appropriate layer	and level values is important to avoid
     massive amounts of	debugging output.  Check the code to see which you
     need.

     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.

     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.  Non-i386 platforms
     do	not support operating systems which do not use ACPI.  Disabling	all or
     part of ACPI on non-i386 platforms	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-
     nel environment variable debug.acpi.disabled.  Multiple entries can be
     listed, separated by a space.

     ACPI sub-devices and features that	can be disabled:

     all	  Disable all ACPI features and	devices.

     acad	  (device) Supports AC adapter.

     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.

     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.

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	workaround 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(1) utilities and some	ACPI knowledge.

TUNABLES
     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
	     Selectively disables portions of ACPI for debugging purposes.

     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.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.osname
	     Some systems' ASL may have	problems because they look for names
	     of	Microsoft operating systems.  This tunable overrides the value
	     of	the "\_OS" object from its default of "FreeBSD".

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

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

SYSCTLS
     hw.acpi.cpu.throttle_max
	     Maximum value for CPU throttling, equal to	100% of	the clock
	     rate.

     hw.acpi.cpu.throttle_state
	     Get or set	the current throttling state, from 1 to
	     hw.acpi.cpu.throttle_max.	This scales back the CPU clock rate
	     and the corresponding power consumption.

     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.

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.

FreeBSD	9.2			 June 30, 2004			   FreeBSD 9.2

NAME | SYNOPSIS | DESCRIPTION | ENVIRONMENT | OVERRIDING YOUR BIOS BYTECODE | TUNABLES | SYSCTLS | COMPATIBILITY | SEE ALSO | AUTHORS | BUGS

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