freebsd-skq/share/man/man4/acpi.4

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.Dd December 13, 2004
.Dt ACPI 4
.Os
.Sh NAME
.Nm acpi
.Nd Advanced Configuration and Power Management support
.Sh SYNOPSIS
.Cd "device acpi"
.Pp
.Cd "options ACPI_DEBUG"
.Sh DESCRIPTION
The
.Nm
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.
.Pp
Note that the
.Nm
driver is automatically loaded by the bootloader, and should only be
compiled into the kernel on platforms where ACPI is mandatory.
.Sh SYSCTLS
The
.Nm
driver is intended to provide power management without user intervention.
Thus, some of these sysctls are controlled automatically by the
.Nm power_profile
rc script, which can be configured via
.Xr rc.conf 5 .
If you specify values manually, they may be overridden.
.Bl -tag -width indent
.It Va hw.acpi.cpu.throttle_max
Maximum value for CPU throttling, equal to 100% of the clock rate.
.It Va hw.acpi.cpu.throttle_state
Get or set the current throttling state, from 1 to
.Va hw.acpi.cpu.throttle_max .
This scales back the CPU clock rate and the corresponding power consumption.
.It Va hw.acpi.cpu.cx_usage
Debugging information listing the percent of total usage for each sleep state.
The values are reset when
.Va hw.acpi.cpu.cx_lowest
is modified.
.It Va 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,
.Va machdep.cpu_idle_hlt
must be set to 1.
.It Va 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.
.El
.Sh TUNABLES
Tunables can be set at the
.Xr loader 8
prompt before booting the kernel or stored in
.Pa /boot/loader.conf .
.Bl -tag -width indent
.It Va acpi_dsdt_load
Enables loading of a custom ACPI DSDT.
.It Va acpi_dsdt_name
Name of the DSDT table to load, if loading is enabled.
.It Va debug.acpi.disabled
Selectively disables portions of ACPI for debugging purposes.
.It Va 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.
.It Va hw.acpi.ec.poll_timeout
Delay in milliseconds to wait for the EC to respond.
Try increasing this number if you get the error
.Er AE_NO_HARDWARE_RESPONSE .
.It Va 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
.Qq Li \e_OS
object from its default of
.Qq Li FreeBSD .
.It Va hw.acpi.pci.link.%d.%d.%d.irq
Override the interrupt to use.
.It Va 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.
.It Va 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 can't handle parallel method execution.
It is off by default since this breaks recursive methods and some IBMs use 
such code.
.It Va hw.acpi.verbose
Turn on verbose debugging information about what ACPI is doing.
.El
.Sh DISABLING ACPI
Since ACPI support on different platforms varies greatly, there are many
debugging and tuning options available.
.Pp
For machines known not to work with
.Nm
enabled, there is a BIOS blacklist.
Currently, the blacklist only controls whether
.Nm
should be disabled or not.
In the future, it will have more granularity to control features (the
infrastructure for that is already there).
.Pp
To enable
.Nm
(for debugging purposes, etc.) on machines that are on the blacklist, set the
kernel environment variable
.Va hint.acpi.0.disabled
to 0.
Before trying this, consider updating your BIOS to a more recent version that
may be compatible with ACPI.
.Pp
To disable the
.Nm
driver completely, set the kernel environment variable
.Va hint.acpi.0.disabled
to 1.
.Pp
Some i386 machines totally fail to operate with some or all of ACPI disabled.
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.
.Pp
The
.Nm
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
.Va debug.acpi.disabled .
Multiple entries can be listed, separated by a space.
.Pp
ACPI sub-devices and features that can be disabled:
.Bl -tag -width sysresource
.It Li all
Disable all ACPI features and devices.
.It Li acad
.Pq Vt device
Supports AC adapter.
.It Li bus
.Pq Vt feature
Probes and attaches subdevices.
Disabling will avoid scanning the ACPI namespace entirely.
.It Li children
.Pq Vt feature
Attaches standard ACPI sub-drivers and devices enumerated in the
ACPI namespace.
Disabling this has a similar effect to disabling
.Dq Li bus ,
except that the
ACPI namespace will still be scanned.
.It Li button
.Pq Vt device
Supports ACPI button devices (typically power and sleep buttons).
.It Li cmbat
.Pq Vt device
Control-method batteries device.
.It Li cpu
.Pq Vt device
Supports CPU power-saving and speed-setting functions.
.It Li ec
.Pq Vt device
Supports the ACPI Embedded Controller interface, used to communicate
with embedded platform controllers.
.It Li isa
.Pq Vt device
Supports an ISA bus bridge defined in the ACPI namespace,
typically as a child of a PCI bus.
.It Li lid
.Pq Vt device
Supports an ACPI laptop lid switch, which typically puts a
system to sleep.
.It Li quirks
.Pq Vt feature
Do not honor quirks.
Quirks automatically disable ACPI functionality based on the XSDT table's
OEM vendor name and revision date.
.It Li pci
.Pq Vt device
Supports Host to PCI bridges.
.It Li pci_link
.Pq Vt feature
Performs PCI interrupt routing.
.It Li sysresource
.Pq Vt device
Pseudo-devices containing resources which ACPI claims.
.It Li thermal
.Pq Vt device
Supports system cooling and heat management.
.It Li timer
.Pq Vt device
Implements a timecounter using the ACPI fixed-frequency timer.
.El
.Pp
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
.Va 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.
.Sh DEBUGGING OUTPUT
To enable debugging output,
.Nm
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.
.Pp
Both layers and levels are specified as a whitespace-separated list of
tokens, with layers listed in
.Va debug.acpi.layer
and levels in
.Va debug.acpi.level .
The supported layers are:
.Pp
.Bl -tag -compact -width ACPI_CA_DISASSEMBLER
.It Li ACPI_UTILITIES
.It Li ACPI_HARDWARE
.It Li ACPI_EVENTS
.It Li ACPI_TABLES
.It Li ACPI_NAMESPACE
.It Li ACPI_PARSER
.It Li ACPI_DISPATCHER
.It Li ACPI_EXECUTER
.It Li ACPI_RESOURCES
.It Li ACPI_CA_DEBUGGER
.It Li ACPI_OS_SERVICES
.It Li ACPI_CA_DISASSEMBLER
.It Li ACPI_ALL_COMPONENTS
All the above ACPI-CA components
.It Li ACPI_AC_ADAPTER
AC adapter driver
.It Li ACPI_BATTERY
Control-method battery driver
.It Li ACPI_BUS
ACPI, ISA, and PCI bus drivers
.It Li ACPI_BUTTON
Power and sleep button driver
.It Li ACPI_EC
Embedded controller driver
.It Li ACPI_FAN
Fan driver
.It Li ACPI_OEM
Platform-specific driver for hotkeys, LED, etc.
.It Li ACPI_POWER
Power resource driver
.It Li ACPI_PROCESSOR
CPU driver
.It Li ACPI_THERMAL
Thermal zone driver
.It Li ACPI_TIMER
Timer driver
.It Li ACPI_ALL_DRIVERS
All the above
.Fx
ACPI drivers
.El
.Pp
The supported levels are:
.Pp
.Bl -tag -compact -width ACPI_LV_AML_DISASSEMBLE
.It Li ACPI_LV_ERROR
.It Li ACPI_LV_WARN
.It Li ACPI_LV_INIT
.It Li ACPI_LV_DEBUG_OBJECT
.It Li ACPI_LV_INFO
.It Li ACPI_LV_ALL_EXCEPTIONS
All the above errors and warnings
.It Li ACPI_LV_INIT_NAMES
.It Li ACPI_LV_PARSE
.It Li ACPI_LV_LOAD
.It Li ACPI_LV_DISPATCH
.It Li ACPI_LV_EXEC
.It Li ACPI_LV_NAMES
.It Li ACPI_LV_OPREGION
.It Li ACPI_LV_BFIELD
.It Li ACPI_LV_TABLES
.It Li ACPI_LV_VALUES
.It Li ACPI_LV_OBJECTS
.It Li ACPI_LV_RESOURCES
.It Li ACPI_LV_USER_REQUESTS
.It Li ACPI_LV_PACKAGE
.It Li ACPI_LV_VERBOSITY1
.It Li ACPI_LV_ALLOCATIONS
.It Li ACPI_LV_FUNCTIONS
.It Li ACPI_LV_OPTIMIZATIONS
.It Li ACPI_LV_VERBOSITY2
.It Li ACPI_LV_ALL
.It Li ACPI_LV_MUTEX
.It Li ACPI_LV_THREADS
.It Li ACPI_LV_IO
.It Li ACPI_LV_INTERRUPTS
.It Li ACPI_LV_VERBOSITY3
.It Li ACPI_LV_AML_DISASSEMBLE
.It Li ACPI_LV_VERBOSE_INFO
.It Li ACPI_LV_FULL_TABLES
.It Li ACPI_LV_EVENTS
.It Li ACPI_LV_VERBOSE
.El
.Pp
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.
.Pp
Debugging output by the ACPI CA subsystem is prefixed with the
module name in lowercase, followed by a source line number.
Output from the
.Fx Ns -local
code follows the same format, but
the module name is uppercased.
.Pp
.Sh 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.
.Fx
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.
.Pp
In order to load your AML code, you must edit
.Pa /boot/loader.conf
and include the following lines.
.Bd -literal -offset indent
acpi_dsdt_load="YES"
acpi_dsdt_name="/boot/acpi_dsdt.aml" # You may change this name.
.Ed
.Pp
In order to prepare your AML code, you will need the
.Xr acpidump 8
and
.Xr iasl 1
utilities and some ACPI knowledge.
.Sh COMPATIBILITY
ACPI is only found and supported on i386/ia32, ia64, and amd64.
.Sh SEE ALSO
.Xr kenv 1 ,
.Xr acpi_thermal 4 ,
.Xr device.hints 5 ,
.Xr loader.conf 5 ,
.Xr acpiconf 8 ,
.Xr acpidump 8 ,
.Xr config 8 ,
.Xr iasl 8
.Rs
.%A "Compaq Computer Corporation"
.%A "Intel Corporation"
.%A "Microsoft Corporation"
.%A "Phoenix Technologies Ltd."
.%A "Toshiba Corporation"
.%D August 25, 2003
.%T "Advanced Configuration and Power Interface Specification"
.%O http://acpi.info/spec.htm
.Re
.Sh AUTHORS
.An -nosplit
The ACPI CA subsystem is developed and maintained by
Intel Architecture Labs.
.Pp
The following people made notable contributions to the ACPI subsystem
in
.Fx :
.An Michael Smith ,
.An Takanori Watanabe Aq takawata@jp.FreeBSD.org ,
.An Mitsuru IWASAKI Aq iwasaki@jp.FreeBSD.org ,
.An Munehiro Matsuda ,
.An Nate Lawson ,
the ACPI-jp mailing list at
.Aq acpi-jp@jp.FreeBSD.org ,
and many other contributors.
.Pp
This manual page was written by
.An Michael Smith Aq msmith@FreeBSD.org .
.Sh BUGS
If the
.Nm
driver is loaded as a module when it is already linked as part of the
kernel, odd things may happen.