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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
     (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 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
     portion 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
     uppercased.

     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 environment
     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.  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
     disabled in case of problems.  To disable a sub-driver, list it in the
     kernel 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
                  similar 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
                  functions.

     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-
                  frequency 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
     implementation.  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
             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 transition 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
             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
     contributors.

     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 11.0-PRERELEASE          June 30, 2004         FreeBSD 11.0-PRERELEASE

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

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