path: root/share/man/man4/acpi.4

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.\" $FreeBSD$
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.Dd July 2, 2001
.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 not normally
be compiled into the kernel.
.Sh ENVIRONMENT
This support is still experimental, and thus there are many debugging
and tuning options which are managed via the kernel environment
space, and set in the
.Xr loader 8
before booting the kernel.
.Pp
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.
.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 -item -offset indent -compact
.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
.It
.Li ACPI_BUS
.It
.Li ACPI_SYSTEM
.It
.Li ACPI_POWER
.It
.Li ACPI_EC
.It
.Li ACPI_AC_ADAPTER
.It
.Li ACPI_BATTERY
.It
.Li ACPI_BUTTON
.It
.Li ACPI_PROCESSOR
.It
.Li ACPI_THERMAL
.It
.Li ACPI_FAN
.It
.Li ACPI_ALL_DRIVERS
.El
.Pp
The supported levels are:
.Pp
.Bl -item -offset indent -compact
.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
.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
To disable the
.Nm
driver completely, set the kernel environment variable
.Va 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.
.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.disable .
.Pp
ACPI sub-devices and features that can be disabled:
.Bl -tag -width children
.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 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 pci
.Pq Vt device
Supports Host to PCI bridges.
.It Li cpu
.Pq Vt device
Supports CPU power-saving and speed-setting functions.
.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 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 problem that does not appear in the Microsoft implementation.
So we provide a way to override it with your own AML code.
.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 the 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 TUNABLES
.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.disable
Selectively disables portions of ACPI for debugging purposes.
.It Va hint.acpi.0.disabled
Disables all of ACPI.
.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.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.os_name
Some systems' ASL may have problems because they look for names
of Microsoft operating systems.
This tunable overrides the default value of
.Qq Li FreeBSD .
.It Va hw.acpi.pci.link.%d.%d.%d.irq
Override the interrupt to use.
.It Va hw.acpi.verbose
Turn on verbose debugging information about what ACPI is doing.
.El
.Sh SYSCTLS
.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_history
Debugging information listing all sleep states and the number of
long and short sleeps for each one.
The counters are reset when
.Va hw.acpi.cpu.cx_lowest
is modified.
.It Va hw.acpi.cpu.cx_lowest
Zero-based index of the lowest CPU idle state to use.
A scheduling algorithm will select between 0...index for the state
to use during the next sleep.
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, C1-3.
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.
Deeper sleeps provide more power savings but increased transition
latency when an interrupt occurs.
.El
.Sh COMPATIBILITY
ACPI is only found and supported on i386/ia32, ia64, and amd64.
.Sh SEE ALSO
.Xr acpi_thermal 4 ,
.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.