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/Mi
crosoft/Compaq/Toshiba ACPI standard. This support includes platform hardware dis
covery (superseding 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 mandatory.

SYSCTL VARIABLES

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 algorithm 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 transi; tion latency in
microseconds. Each state has a type (e.g., C2). C1; is equivalent to the ia32 HLT instruction, C2 provides a; deeper sleep with
the same semantics, and C3 provides the deepest; sleep but additionally 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 oc; curs.

LOADER 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 en; abled.
debug.acpi.disabled: Selectively disables portions of ACPI for debugging; purposes.
debug.acpi.max_threads: Specify the number of task threads that are started; on boot.
Limiting this to 1 may help work around various; BIOSes that cannot handle parallel requests. The default value is; 3.
debug.acpi.quirks: 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 prob; lems for you.
hw.acpi.serialize_methods: Allow override of whether methods execute in paral; lel or not.
Enable this for serial behavior, which fixes "AE_AL; READY_EXISTS"
errors for AML that really cannot handle parallel; method execution. It is off by default since this breaks recur; sive 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 blacklist. Currently, the blacklist only controls whether acpi
should be disabled 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 envi
ronment variable hint.acpi.0.disabled to 1.
Some i386 machines totally fail to operate with some or all
of ACPI disabled. Other i386 machines fail with ACPI enabled. Dis
abling 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 se
lectively disabled in case of problems. To disable a sub-driver, list it
in the kernel environment variable debug.acpi.disabled. Multiple en
tries 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 en; tirely.
children (feature) Attaches standard ACPI sub
drivers and devices: enumerated in the ACPI namespace. Dis; abling this has a
similar effect to disabling ``bus'', except; that the
ACPI namespace will still be scanned.
button (device) Supports ACPI button devices (typ
ically power: and sleep buttons).
cmbat (device) Control-method batteries device.
cpu (device) Supports CPU power-saving and
speed-setting: functions.
ec (device) Supports the ACPI Embedded Con
troller inter: face, 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 typi: cally puts a system to sleep.
quirks (feature) Do not honor quirks. Quirks au
tomatically: disable ACPI functionality based on the XS; DT 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 re
sources which ACPI: claims.
thermal (device) Supports system cooling and heat
management.
timer (device) Implements a timecounter using the
ACPI fixed: frequency timer.
video (device) Supports acpi_video(4) which may
conflict with: agp(4) 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 particular kind of debugging output.
Both layers and levels are specified as a whitespace-sepa
rated list of tokens, with layers listed in debug.acpi.layer and levels in debug.acpi.level.
The first set of layers is for ACPI-CA components, and the
second is for FreeBSD drivers. The ACPI-CA layer descriptions include the
prefix for the files they refer to. The supported layers are:
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 inter
preter 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 (un
used) 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 ACPI_LV_VERBOSITY3 All the previous levels ACPI_LV_AML_DISASSEMBLE ACPI_LV_VERBOSE_INFO ACPI_LV_FULL_TABLES ACPI_LV_EVENTS ACPI_LV_VERBOSE All levels after "ACPI_LV_VER
BOSITY3"
Selection of the appropriate layer and level values is im
portant to avoid massive amounts of debugging output. For example, the fol
lowing configuration is a good way to gather initial information. It en
ables 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 uppercased.

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 Mi
crosoft implementation. 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.

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 <takawa
ta@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 contributors.
This manual page was written by Michael Smith <msmith@FreeB
SD.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.
BSD February 13, 2005

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In section

See also

acpi(4)

NAME

SYNOPSIS

DESCRIPTION

SYSCTL VARIABLES

LOADER TUNABLES

DISABLING ACPI

DEBUGGING OUTPUT

OVERRIDING YOUR BIOS BYTECODE

COMPATIBILITY

SEE ALSO

AUTHORS

BUGS