2 .\" Copyright (c) 2001 Michael Smith
3 .\" All rights reserved.
5 .\" Redistribution and use in source and binary forms, with or without
6 .\" modification, are permitted provided that the following conditions
8 .\" 1. Redistributions of source code must retain the above copyright
9 .\" notice, this list of conditions and the following disclaimer.
10 .\" 2. Redistributions in binary form must reproduce the above copyright
11 .\" notice, this list of conditions and the following disclaimer in the
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14 .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 .\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 .\" $FreeBSD: src/share/man/man4/acpi.4,v 1.61.8.1 2009/04/15 03:14:26 kensmith Exp $
33 .Nd Advanced Configuration and Power Management support
37 .Cd "options ACPI_DEBUG"
42 driver provides support for the Intel/Microsoft/Compaq/Toshiba ACPI
44 This support includes platform hardware discovery (superseding the
45 PnP and PCI BIOS), as well as power management (superseding APM) and
47 ACPI core support is provided by the ACPI CA reference implementation
52 driver is automatically loaded by the
55 compiled into the kernel on platforms where ACPI is mandatory.
59 driver is intended to provide power management without user intervention.
60 If the default settings are not optimal, the following sysctls can be
61 used to modify or monitor
64 .Bl -tag -width indent
66 AC line state (1 means online, 0 means on battery power).
67 .It Va hw.acpi.cpu.cx_usage
68 Debugging information listing the percent of total usage for each sleep state.
69 The values are reset when
70 .Va hw.acpi.cpu.cx_lowest
72 .It Va hw.acpi.cpu.cx_lowest
73 Lowest Cx state to use for idling the CPU.
74 A scheduling algorithm will select states between
77 as system load dictates.
78 To enable ACPI CPU idling control,
79 .Va machdep.cpu_idle_hlt
80 must be set to 2 (the default value).
81 .It Va hw.acpi.cpu.cx_supported
82 List of supported CPU idle states and their transition latency
84 Each state has a type (e.g.,
87 is equivalent to the ia32
92 sleep with the same semantics, and
94 provides the deepest sleep
95 but additionally requires bus mastering to be disabled.
98 provide even more power savings with the same
102 Deeper sleeps provide more power savings but increased transition
103 latency when an interrupt occurs.
104 .It Va hw.acpi.disable_on_reboot
105 Disable ACPI during the reboot process.
106 Most systems reboot fine with ACPI still enabled, but some require
107 exiting to legacy mode first.
108 Default is 0, leave ACPI enabled.
109 .It Va hw.acpi.handle_reboot
110 Use the ACPI Reset Register capability to reboot the system.
111 Default is 0, use legacy reboot support.
112 Some newer systems require use of this register, while some only work
113 with legacy rebooting support.
114 .It Va hw.acpi.lid_switch_state
116 .Pq Li S1 Ns \[en] Ns Li S5
117 to enter when the lid switch (i.e., a notebook screen) is closed.
121 .It Va hw.acpi.power_button_state
123 .Pq Li S1 Ns \[en] Ns Li S5
124 to enter when the power button is pressed.
128 .It Va hw.acpi.reset_video
129 Reset the video adapter from real mode during the resume path.
130 Some systems need this help, others have display problems if it is enabled.
131 Default is 0 (disabled).
132 .It Va hw.acpi.s4bios
133 Indicate whether the system supports
135 This means that the BIOS can handle all the functions of suspending the
137 Otherwise, the OS is responsible for suspending to disk
139 Most current systems do not support
141 .It Va hw.acpi.sleep_button_state
143 .Pq Li S1 Ns \[en] Ns Li S5
144 to enter when the sleep button is pressed.
145 This is usually a special function button on the keyboard.
149 .It Va hw.acpi.sleep_delay
150 Wait this number of seconds between preparing the system to suspend and
151 actually entering the suspend state.
153 .It Va hw.acpi.supported_sleep_state
155 .Pq Li S1 Ns \[en] Ns Li S5
156 supported by the BIOS.
157 .Bl -tag -width indent
159 Quick suspend to RAM.
160 The CPU enters a lower power state, but most peripherals are left running.
162 Lower power state than
164 but with the same basic characteristics.
165 Not supported by many systems.
168 Most devices are powered off, and the system stops running except for
172 All devices are powered off, and the system stops running.
173 When resuming, the system starts as if from a cold power on.
180 System shuts down cleanly and powers off.
182 .It Va hw.acpi.verbose
183 Enable verbose printing from the various ACPI subsystems.
186 Tunables can be set at the
188 prompt before booting the kernel or stored in
189 .Pa /boot/loader.conf .
190 Many of these tunables also have a matching
192 entry for access after boot.
193 .Bl -tag -width indent
194 .It Va acpi_dsdt_load
195 Enables loading of a custom ACPI DSDT.
196 .It Va acpi_dsdt_name
197 Name of the DSDT table to load, if loading is enabled.
198 .It Va debug.acpi.disabled
199 Selectively disables portions of ACPI that are enabled by default, for
201 .It Va debug.acpi.enabled
202 Selectively enables portions of ACPI that are disabled by default, for
204 .It Va debug.acpi.max_threads
205 Specify the number of task threads that are started on boot.
206 Limiting this to 1 may help work around various BIOSes that cannot
207 handle parallel requests.
208 The default value is 3.
209 .It Va debug.acpi.quirks
210 Override any automatic quirks completely.
211 .It Va debug.acpi.resume_beep
212 Beep the PC speaker on resume.
213 This can help diagnose suspend/resume problems.
214 Default is 0 (disabled).
215 .It Va hint.acpi.0.disabled
216 Set this to 1 to disable all of ACPI.
217 If ACPI has been disabled on your system due to a blacklist entry for your
218 BIOS, you can set this to 0 to re-enable ACPI for testing.
219 .It Va hw.acpi.ec.poll_timeout
220 Delay in milliseconds to wait for the EC to respond.
221 Try increasing this number if you get the error
222 .Qq Li AE_NO_HARDWARE_RESPONSE .
223 .It Va hw.acpi.host_mem_start
224 Override the assumed memory starting address for PCI host bridges.
225 .It Va hw.acpi.reset_video
226 Enables calling the VESA reset BIOS vector on the resume path.
227 This can fix some graphics cards that have problems such as LCD white-out
229 Default is 0 (disabled).
230 .It Va hw.acpi.auto_serialize_methods
231 Auto-serialization of control methods to proactively prevent problems with
232 ill-behaved reentrant control methods that create named ACPI objects.
233 Default is 1 (enabled).
234 .It Va hw.acpi.verbose
235 Turn on verbose debugging information about what ACPI is doing.
236 .It Va hw.pci.link.%s.%d.irq
237 Override the interrupt to use for this link and index.
238 This capability should be used carefully, and only if a device is not
243 is the name of the link (e.g., LNKA).
245 is the resource index when the link supports multiple IRQs.
246 Most PCI links only have one IRQ resource, so the below form should be used.
247 .It Va hw.pci.link.%s.irq
248 Override the interrupt to use.
249 This capability should be used carefully, and only if a device is not
254 is the name of the link (e.g., LNKA).
257 Since ACPI support on different platforms varies greatly, there are many
258 debugging and tuning options available.
260 For machines known not to work with
262 enabled, there is a BIOS blacklist.
263 Currently, the blacklist only controls whether
265 should be disabled or not.
266 In the future, it will have more granularity to control features (the
267 infrastructure for that is already there).
271 (for debugging purposes, etc.) on machines that are on the blacklist, set the
272 kernel environment variable
273 .Va hint.acpi.0.disabled
275 Before trying this, consider updating your BIOS to a more recent version that
276 may be compatible with ACPI.
280 driver completely, set the kernel environment variable
281 .Va hint.acpi.0.disabled
284 Some i386 machines totally fail to operate with some or all of ACPI disabled.
285 Other i386 machines fail with ACPI enabled.
286 Disabling all or part of ACPI on non-i386 platforms (i.e., platforms where
287 ACPI support is mandatory) may result in a non-functional system.
291 driver comprises a set of drivers, which may be selectively disabled
293 To disable a sub-driver, list it in the kernel
295 .Va debug.acpi.disabled .
296 Multiple entries can be listed, separated by a space.
298 ACPI sub-devices and features that can be disabled:
299 .Bl -tag -width ".Li sysresource"
301 Disable all ACPI features and devices.
307 Probes and attaches subdevices.
308 Disabling will avoid scanning the ACPI namespace entirely.
311 Attaches standard ACPI sub-drivers and devices enumerated in the
313 Disabling this has a similar effect to disabling
316 ACPI namespace will still be scanned.
319 Supports ACPI button devices (typically power and sleep buttons).
322 Control-method batteries device.
325 Supports CPU power-saving and speed-setting functions.
328 Supports CPU power-saving.
331 will also disable this device.
334 Supports CPU speed-setting.
337 will also disable this device.
340 Supports the ACPI Embedded Controller interface, used to communicate
341 with embedded platform controllers.
344 Supports an ISA bus bridge defined in the ACPI namespace,
345 typically as a child of a PCI bus.
348 Supports an ACPI laptop lid switch, which typically puts a
353 Quirks automatically disable ACPI functionality based on the XSDT table's
354 OEM vendor name and revision date.
357 Supports Host to PCI bridges.
360 Performs PCI interrupt routing.
363 Pseudo-devices containing resources which ACPI claims.
366 Supports system cooling and heat management.
369 Implements a timecounter using the ACPI fixed-frequency timer.
372 Supports the High Precision Event Timer.
377 which may conflict with
384 .\"driver comprises a set of drivers,
385 .\"which may be selectively enabled in case of testing.
386 .\"To enable a sub-driver,
387 .\"list it in the kernel environment variable
388 .\".Va debug.acpi.enabled .
389 .\"Multiple entries can be listed,
390 .\"separated by a space.
392 .\"ACPI sub-devices and features that can be enabled:
393 .\".Bl -tag -width ".Li sysresource"
397 It is also possible to avoid portions of the ACPI namespace which
398 may be causing problems, by listing the full path of the root of
399 the region to be avoided in the kernel environment variable
400 .Va debug.acpi.avoid .
401 The object and all of its children will be ignored during the
402 bus/children scan of the namespace.
403 The ACPI CA code will still know about the avoided region.
405 To enable debugging output,
407 must be compiled with
408 .Cd "options ACPI_DEBUG" .
409 Debugging output is separated between layers and levels, where a layer is
410 a component of the ACPI subsystem, and a level is a particular kind
413 Both layers and levels are specified as a whitespace-separated list of
414 tokens, with layers listed in
417 .Va debug.acpi.level .
419 The first set of layers is for ACPI-CA components, and the second is for
422 The ACPI-CA layer descriptions include the prefix for the files they
424 The supported layers are:
426 .Bl -tag -compact -width ".Li ACPI_CA_DISASSEMBLER"
427 .It Li ACPI_UTILITIES
428 Utility ("ut") functions
430 Hardware access ("hw")
435 .It Li ACPI_NAMESPACE
436 Namespace evaluation ("ns")
439 .It Li ACPI_DISPATCHER
440 Internal representation of interpreter state ("ds")
442 Execute AML methods ("ex")
443 .It Li ACPI_RESOURCES
444 Resource parsing ("rs")
445 .It Li ACPI_CA_DEBUGGER
446 Debugger implementation ("db", "dm")
447 .It Li ACPI_OS_SERVICES
448 Usermode support routines ("os")
449 .It Li ACPI_CA_DISASSEMBLER
450 Disassembler implementation (unused)
451 .It Li ACPI_ALL_COMPONENTS
452 All the above ACPI-CA components
453 .It Li ACPI_AC_ADAPTER
456 Control-method battery driver
458 ACPI, ISA, and PCI bus drivers
460 Power and sleep button driver
462 Embedded controller driver
466 Platform-specific driver for hotkeys, LED, etc.
468 Power resource driver
469 .It Li ACPI_PROCESSOR
475 .It Li ACPI_ALL_DRIVERS
481 The supported levels are:
483 .Bl -tag -compact -width ".Li ACPI_LV_AML_DISASSEMBLE"
485 Fatal error conditions
487 Warnings and potential problems
489 Initialization progress
490 .It Li ACPI_LV_DEBUG_OBJECT
493 General information and progress
494 .It Li ACPI_LV_ALL_EXCEPTIONS
495 All the previous levels
496 .It Li ACPI_LV_INIT_NAMES
499 .It Li ACPI_LV_DISPATCH
502 .It Li ACPI_LV_OPREGION
503 .It Li ACPI_LV_BFIELD
504 .It Li ACPI_LV_TABLES
505 .It Li ACPI_LV_VALUES
506 .It Li ACPI_LV_OBJECTS
507 .It Li ACPI_LV_RESOURCES
508 .It Li ACPI_LV_USER_REQUESTS
509 .It Li ACPI_LV_PACKAGE
510 .It Li ACPI_LV_VERBOSITY1
511 All the previous levels
512 .It Li ACPI_LV_ALLOCATIONS
513 .It Li ACPI_LV_FUNCTIONS
514 .It Li ACPI_LV_OPTIMIZATIONS
515 .It Li ACPI_LV_VERBOSITY2
518 .It Li ACPI_LV_THREADS
520 .It Li ACPI_LV_INTERRUPTS
521 .It Li ACPI_LV_VERBOSITY3
522 All the previous levels
523 .It Li ACPI_LV_AML_DISASSEMBLE
524 .It Li ACPI_LV_VERBOSE_INFO
525 .It Li ACPI_LV_FULL_TABLES
526 .It Li ACPI_LV_EVENTS
527 .It Li ACPI_LV_VERBOSE
529 .Qq Li ACPI_LV_VERBOSITY3
532 Selection of the appropriate layer and level values is important
533 to avoid massive amounts of debugging output.
534 For example, the following configuration is a good way to gather initial
536 It enables debug output for both ACPI-CA and the
538 driver, printing basic information about errors, warnings, and progress.
539 .Bd -literal -offset indent
540 debug.acpi.layer="ACPI_ALL_COMPONENTS ACPI_ALL_DRIVERS"
541 debug.acpi.level="ACPI_LV_ALL_EXCEPTIONS"
544 Debugging output by the ACPI CA subsystem is prefixed with the
545 module name in lowercase, followed by a source line number.
548 code follows the same format, but
549 the module name is uppercased.
550 .Sh OVERRIDING YOUR BIOS BYTECODE
551 ACPI interprets bytecode named AML
552 (ACPI Machine Language)
553 provided by the BIOS vendor as a memory image at boot time.
554 Sometimes, the AML code contains a bug that does not appear when parsed
555 by the Microsoft implementation.
557 provides a way to override it with your own AML code to work around
558 or debug such problems.
559 Note that all AML in your DSDT and any SSDT tables is overridden.
561 In order to load your AML code, you must edit
562 .Pa /boot/loader.conf
563 and include the following lines.
564 .Bd -literal -offset indent
566 acpi_dsdt_name="/boot/acpi_dsdt.aml" # You may change this name.
569 In order to prepare your AML code, you will need the
573 utilities and some ACPI knowledge.
575 ACPI is only found and supported on i386/ia32, ia64, and x86_64.
581 .Xr acpi_panasonic 4 ,
584 .Xr acpi_thinkpad 4 ,
598 .%A "Compaq Computer Corporation"
599 .%A "Intel Corporation"
600 .%A "Microsoft Corporation"
601 .%A "Phoenix Technologies Ltd."
602 .%A "Toshiba Corporation"
604 .%T "Advanced Configuration and Power Interface Specification"
605 .%O http://acpi.info/spec.htm
609 The ACPI CA subsystem is developed and maintained by
610 Intel Architecture Labs.
612 The following people made notable contributions to the ACPI subsystem
616 .An Takanori Watanabe Aq Mt takawata@jp.FreeBSD.org ,
617 .An Mitsuru IWASAKI Aq Mt iwasaki@jp.FreeBSD.org ,
618 .An Munehiro Matsuda ,
620 the ACPI-jp mailing list at
621 .Aq Mt acpi-jp@jp.FreeBSD.org ,
622 and many other contributors.
624 This manual page was written by
625 .An Michael Smith Aq Mt msmith@FreeBSD.org .
627 Many BIOS versions have serious bugs that may cause system instability,
628 break suspend/resume, or prevent devices from operating properly due to
629 IRQ routing problems.
630 Upgrade your BIOS to the latest version available from the vendor before
631 deciding it is a problem with
636 .\"CPU idle power management drive conflicts with the local APIC (LAPIC)
638 .\"Disable APIC mode with
639 .\".Va hint.apic.0.disabled
644 .\"states if APIC mode is enabled.