2 .\" Copyright (c) 2001 Michael Smith
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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.serialize_methods
231 Allow override of whether methods execute in parallel or not.
232 Enable this for serial behavior, which fixes
233 .Qq Li AE_ALREADY_EXISTS
235 AML that really cannot handle parallel method execution.
236 It is off by default since this breaks recursive methods and some IBMs use
238 .It Va hw.acpi.verbose
239 Turn on verbose debugging information about what ACPI is doing.
240 .It Va hw.pci.link.%s.%d.irq
241 Override the interrupt to use for this link and index.
242 This capability should be used carefully, and only if a device is not
247 is the name of the link (e.g., LNKA).
249 is the resource index when the link supports multiple IRQs.
250 Most PCI links only have one IRQ resource, so the below form should be used.
251 .It Va hw.pci.link.%s.irq
252 Override the interrupt to use.
253 This capability should be used carefully, and only if a device is not
258 is the name of the link (e.g., LNKA).
261 Since ACPI support on different platforms varies greatly, there are many
262 debugging and tuning options available.
264 For machines known not to work with
266 enabled, there is a BIOS blacklist.
267 Currently, the blacklist only controls whether
269 should be disabled or not.
270 In the future, it will have more granularity to control features (the
271 infrastructure for that is already there).
275 (for debugging purposes, etc.) on machines that are on the blacklist, set the
276 kernel environment variable
277 .Va hint.acpi.0.disabled
279 Before trying this, consider updating your BIOS to a more recent version that
280 may be compatible with ACPI.
284 driver completely, set the kernel environment variable
285 .Va hint.acpi.0.disabled
288 Some i386 machines totally fail to operate with some or all of ACPI disabled.
289 Other i386 machines fail with ACPI enabled.
290 Disabling all or part of ACPI on non-i386 platforms (i.e., platforms where
291 ACPI support is mandatory) may result in a non-functional system.
295 driver comprises a set of drivers, which may be selectively disabled
297 To disable a sub-driver, list it in the kernel
299 .Va debug.acpi.disabled .
300 Multiple entries can be listed, separated by a space.
302 ACPI sub-devices and features that can be disabled:
303 .Bl -tag -width ".Li sysresource"
305 Disable all ACPI features and devices.
311 Probes and attaches subdevices.
312 Disabling will avoid scanning the ACPI namespace entirely.
315 Attaches standard ACPI sub-drivers and devices enumerated in the
317 Disabling this has a similar effect to disabling
320 ACPI namespace will still be scanned.
323 Supports ACPI button devices (typically power and sleep buttons).
326 Control-method batteries device.
329 Supports CPU power-saving and speed-setting functions.
332 Supports CPU power-saving.
335 will also disable this device.
338 Supports CPU speed-setting.
341 will also disable this device.
344 Supports the ACPI Embedded Controller interface, used to communicate
345 with embedded platform controllers.
348 Supports an ISA bus bridge defined in the ACPI namespace,
349 typically as a child of a PCI bus.
352 Supports an ACPI laptop lid switch, which typically puts a
357 Quirks automatically disable ACPI functionality based on the XSDT table's
358 OEM vendor name and revision date.
361 Supports Host to PCI bridges.
364 Performs PCI interrupt routing.
367 Pseudo-devices containing resources which ACPI claims.
370 Supports system cooling and heat management.
373 Implements a timecounter using the ACPI fixed-frequency timer.
378 which may conflict with
385 driver comprises a set of drivers,
386 which may be selectively enabled in case of testing.
387 To enable a sub-driver,
388 list it in the kernel environment variable
389 .Va debug.acpi.enabled .
390 Multiple entries can be listed,
391 separated by a space.
393 ACPI sub-devices and features that can be enabled:
394 .Bl -tag -width ".Li sysresource"
400 It is also possible to avoid portions of the ACPI namespace which
401 may be causing problems, by listing the full path of the root of
402 the region to be avoided in the kernel environment variable
403 .Va debug.acpi.avoid .
404 The object and all of its children will be ignored during the
405 bus/children scan of the namespace.
406 The ACPI CA code will still know about the avoided region.
408 To enable debugging output,
410 must be compiled with
411 .Cd "options ACPI_DEBUG" .
412 Debugging output is separated between layers and levels, where a layer is
413 a component of the ACPI subsystem, and a level is a particular kind
416 Both layers and levels are specified as a whitespace-separated list of
417 tokens, with layers listed in
420 .Va debug.acpi.level .
422 The first set of layers is for ACPI-CA components, and the second is for
425 The ACPI-CA layer descriptions include the prefix for the files they
427 The supported layers are:
429 .Bl -tag -compact -width ".Li ACPI_CA_DISASSEMBLER"
430 .It Li ACPI_UTILITIES
431 Utility ("ut") functions
433 Hardware access ("hw")
438 .It Li ACPI_NAMESPACE
439 Namespace evaluation ("ns")
442 .It Li ACPI_DISPATCHER
443 Internal representation of interpreter state ("ds")
445 Execute AML methods ("ex")
446 .It Li ACPI_RESOURCES
447 Resource parsing ("rs")
448 .It Li ACPI_CA_DEBUGGER
449 Debugger implementation ("db", "dm")
450 .It Li ACPI_OS_SERVICES
451 Usermode support routines ("os")
452 .It Li ACPI_CA_DISASSEMBLER
453 Disassembler implementation (unused)
454 .It Li ACPI_ALL_COMPONENTS
455 All the above ACPI-CA components
456 .It Li ACPI_AC_ADAPTER
459 Control-method battery driver
461 ACPI, ISA, and PCI bus drivers
463 Power and sleep button driver
465 Embedded controller driver
469 Platform-specific driver for hotkeys, LED, etc.
471 Power resource driver
472 .It Li ACPI_PROCESSOR
478 .It Li ACPI_ALL_DRIVERS
484 The supported levels are:
486 .Bl -tag -compact -width ".Li ACPI_LV_AML_DISASSEMBLE"
488 Fatal error conditions
490 Warnings and potential problems
492 Initialization progress
493 .It Li ACPI_LV_DEBUG_OBJECT
496 General information and progress
497 .It Li ACPI_LV_ALL_EXCEPTIONS
498 All the previous levels
499 .It Li ACPI_LV_INIT_NAMES
502 .It Li ACPI_LV_DISPATCH
505 .It Li ACPI_LV_OPREGION
506 .It Li ACPI_LV_BFIELD
507 .It Li ACPI_LV_TABLES
508 .It Li ACPI_LV_VALUES
509 .It Li ACPI_LV_OBJECTS
510 .It Li ACPI_LV_RESOURCES
511 .It Li ACPI_LV_USER_REQUESTS
512 .It Li ACPI_LV_PACKAGE
513 .It Li ACPI_LV_VERBOSITY1
514 All the previous levels
515 .It Li ACPI_LV_ALLOCATIONS
516 .It Li ACPI_LV_FUNCTIONS
517 .It Li ACPI_LV_OPTIMIZATIONS
518 .It Li ACPI_LV_VERBOSITY2
521 .It Li ACPI_LV_THREADS
523 .It Li ACPI_LV_INTERRUPTS
524 .It Li ACPI_LV_VERBOSITY3
525 All the previous levels
526 .It Li ACPI_LV_AML_DISASSEMBLE
527 .It Li ACPI_LV_VERBOSE_INFO
528 .It Li ACPI_LV_FULL_TABLES
529 .It Li ACPI_LV_EVENTS
530 .It Li ACPI_LV_VERBOSE
532 .Qq Li ACPI_LV_VERBOSITY3
535 Selection of the appropriate layer and level values is important
536 to avoid massive amounts of debugging output.
537 For example, the following configuration is a good way to gather initial
539 It enables debug output for both ACPI-CA and the
541 driver, printing basic information about errors, warnings, and progress.
542 .Bd -literal -offset indent
543 debug.acpi.layer="ACPI_ALL_COMPONENTS ACPI_ALL_DRIVERS"
544 debug.acpi.level="ACPI_LV_ALL_EXCEPTIONS"
547 Debugging output by the ACPI CA subsystem is prefixed with the
548 module name in lowercase, followed by a source line number.
551 code follows the same format, but
552 the module name is uppercased.
553 .Sh OVERRIDING YOUR BIOS BYTECODE
554 ACPI interprets bytecode named AML
555 (ACPI Machine Language)
556 provided by the BIOS vendor as a memory image at boot time.
557 Sometimes, the AML code contains a bug that does not appear when parsed
558 by the Microsoft implementation.
560 provides a way to override it with your own AML code to work around
561 or debug such problems.
562 Note that all AML in your DSDT and any SSDT tables is overridden.
564 In order to load your AML code, you must edit
565 .Pa /boot/loader.conf
566 and include the following lines.
567 .Bd -literal -offset indent
569 acpi_dsdt_name="/boot/acpi_dsdt.aml" # You may change this name.
572 In order to prepare your AML code, you will need the
576 utilities and some ACPI knowledge.
578 ACPI is only found and supported on i386/ia32, ia64, and x86_64.
584 .Xr acpi_panasonic 4 ,
587 .Xr acpi_thinkpad 4 ,
597 .%A "Compaq Computer Corporation"
598 .%A "Intel Corporation"
599 .%A "Microsoft Corporation"
600 .%A "Phoenix Technologies Ltd."
601 .%A "Toshiba Corporation"
603 .%T "Advanced Configuration and Power Interface Specification"
604 .%O http://acpi.info/spec.htm
608 The ACPI CA subsystem is developed and maintained by
609 Intel Architecture Labs.
611 The following people made notable contributions to the ACPI subsystem
615 .An Takanori Watanabe Aq takawata@jp.FreeBSD.org ,
616 .An Mitsuru IWASAKI Aq iwasaki@jp.FreeBSD.org ,
617 .An Munehiro Matsuda ,
619 the ACPI-jp mailing list at
620 .Aq acpi-jp@jp.FreeBSD.org ,
621 and many other contributors.
623 This manual page was written by
624 .An Michael Smith Aq msmith@FreeBSD.org .
626 Many BIOS versions have serious bugs that may cause system instability,
627 break suspend/resume, or prevent devices from operating properly due to
628 IRQ routing problems.
629 Upgrade your BIOS to the latest version available from the vendor before
630 deciding it is a problem with
635 .\"CPU idle power management drive conflicts with the local APIC (LAPIC)
637 .\"Disable APIC mode with
638 .\".Va hint.apic.0.disabled
643 .\"states if APIC mode is enabled.