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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 Note that some variables will be available only if the given hardware supports
66 .Va hw.acpi.acline ) .
67 .Bl -tag -width indent
68 .It Va debug.acpi.enable_debug_objects
69 Enable dumping Debug objects without
70 .Cd "options ACPI_DEBUG" .
71 Default is 0, ignore Debug objects.
72 .It Va dev.cpu.N.cx_usage
73 Debugging information listing the percent of total usage for each sleep state.
74 The values are reset when
75 .Va dev.cpu.N.cx_lowest
77 .It Va dev.cpu.N.cx_lowest
78 Lowest Cx state to use for idling the CPU.
79 A scheduling algorithm will select states between
82 as system load dictates.
83 To enable ACPI CPU idling control,
88 .Va machdep.idle_available .
89 .It Va dev.cpu.N.cx_supported
90 List of supported CPU idle states and their transition latency
92 Each state has a type (e.g.,
95 is equivalent to the ia32
100 sleep with the same semantics, and
102 provides the deepest sleep
103 but additionally requires bus mastering to be disabled.
106 provide even more power savings with the same
110 Deeper sleeps provide more power savings but increased transition
111 latency when an interrupt occurs.
112 .It Va dev.cpu.N.cx_method
113 List of supported CPU idle states and their transition methods, as
114 directed by the firmware.
115 .It Va hw.acpi.acline
116 AC line state (1 means online, 0 means on battery power).
117 .It Va hw.acpi.disable_on_reboot
118 Disable ACPI during the reboot process.
119 Most systems reboot fine with ACPI still enabled, but some require
120 exiting to legacy mode first.
121 Default is 0, leave ACPI enabled.
122 .It Va hw.acpi.handle_reboot
123 Use the ACPI Reset Register capability to reboot the system.
124 Some newer systems require use of this register, while some only work
125 with legacy rebooting support.
126 .It Va hw.acpi.lid_switch_state
128 .Pq Li S1 Ns \[en] Ns Li S5
129 to enter when the lid switch (i.e., a notebook screen) is closed, or
134 .It Va hw.acpi.power_button_state
136 .Pq Li S1 Ns \[en] Ns Li S5
137 to enter when the power button is pressed, or
143 .It Va hw.acpi.reset_video
144 Reset the video adapter from real mode during the resume path.
145 Some systems need this help, others have display problems if it is enabled.
146 Default is 0 (disabled).
147 .It Va hw.acpi.s4bios
148 Indicate whether the system supports
150 This means that the BIOS can handle all the functions of suspending the
152 Otherwise, the OS is responsible for suspending to disk
154 Most current systems do not support
156 .It Va hw.acpi.sleep_button_state
158 .Pq Li S1 Ns \[en] Ns Li S5
159 to enter when the sleep button is pressed.
160 This is usually a special function button on the keyboard.
164 .It Va hw.acpi.sleep_delay
165 Wait this number of seconds between preparing the system to suspend and
166 actually entering the suspend state.
168 .It Va hw.acpi.supported_sleep_state
170 .Pq Li S1 Ns \[en] Ns Li S5
171 supported by the BIOS.
172 .Bl -tag -width indent
174 Quick suspend to RAM.
175 The CPU enters a lower power state, but most peripherals are left running.
177 Lower power state than
179 but with the same basic characteristics.
180 Not supported by many systems.
183 Most devices are powered off, and the system stops running except for
187 All devices are powered off, and the system stops running.
188 When resuming, the system starts as if from a cold power on.
195 System shuts down cleanly and powers off.
197 .It Va hw.acpi.verbose
198 Enable verbose printing from the various ACPI subsystems.
201 Tunables can be set at the
203 prompt before booting the kernel or stored in
204 .Pa /boot/loader.conf .
205 Many of these tunables also have a matching
207 entry for access after boot.
208 .Bl -tag -width indent
209 .It Va acpi_dsdt_load
210 Enables loading of a custom ACPI DSDT.
211 .It Va acpi_dsdt_name
212 Name of the DSDT table to load, if loading is enabled.
213 .It Va debug.acpi.disabled
214 Selectively disables portions of ACPI for debugging purposes.
215 .It Va debug.acpi.interpreter_slack
216 Enable less strict ACPI implementations.
217 Default is 1, ignore common BIOS mistakes.
218 .It Va debug.acpi.max_threads
219 Specify the number of task threads that are started on boot.
220 Limiting this to 1 may help work around various BIOSes that cannot
221 handle parallel requests.
222 The default value is 3.
223 .It Va debug.acpi.quirks
224 Override any automatic quirks completely.
225 .It Va debug.acpi.resume_beep
226 Beep the PC speaker on resume.
227 This can help diagnose suspend/resume problems.
228 Default is 0 (disabled).
229 .It Va hint.acpi.0.disabled
230 Set this to 1 to disable all of ACPI.
231 If ACPI has been disabled on your system due to a blacklist entry for your
232 BIOS, you can set this to 0 to re-enable ACPI for testing.
233 .It Va hw.acpi.ec.poll_timeout
234 Delay in milliseconds to wait for the EC to respond.
235 Try increasing this number if you get the error
236 .Qq Li AE_NO_HARDWARE_RESPONSE .
237 .It Va hw.acpi.host_mem_start
238 Override the assumed memory starting address for PCI host bridges.
239 .It Va hw.acpi.install_interface , hw.acpi.remove_interface
240 Install or remove OS interface(s) to control return value of
243 When an OS interface is specified in
244 .Va hw.acpi.install_interface ,
246 query for the interface returns it is
248 Conversely, when an OS interface is specified in
249 .Va hw.acpi.remove_interface ,
253 Multiple interfaces can be specified in a comma-separated list and
254 any leading white spaces will be ignored.
256 .Qq Li FreeBSD, Linux
257 is a valid list of two interfaces
261 .It Va hw.acpi.reset_video
262 Enables calling the VESA reset BIOS vector on the resume path.
263 This can fix some graphics cards that have problems such as LCD white-out
265 Default is 0 (disabled).
266 .It Va hw.acpi.serialize_methods
267 Allow override of whether methods execute in parallel or not.
268 Enable this for serial behavior, which fixes
269 .Qq Li AE_ALREADY_EXISTS
271 AML that really cannot handle parallel method execution.
272 It is off by default since this breaks recursive methods and some IBMs use
274 .It Va hw.acpi.verbose
275 Turn on verbose debugging information about what ACPI is doing.
276 .It Va hw.pci.link.%s.%d.irq
277 Override the interrupt to use for this link and index.
278 This capability should be used carefully, and only if a device is not
283 is the name of the link (e.g., LNKA).
285 is the resource index when the link supports multiple IRQs.
286 Most PCI links only have one IRQ resource, so the below form should be used.
287 .It Va hw.pci.link.%s.irq
288 Override the interrupt to use.
289 This capability should be used carefully, and only if a device is not
294 is the name of the link (e.g., LNKA).
297 Since ACPI support on different platforms varies greatly, there are many
298 debugging and tuning options available.
300 For machines known not to work with
302 enabled, there is a BIOS blacklist.
303 Currently, the blacklist only controls whether
305 should be disabled or not.
306 In the future, it will have more granularity to control features (the
307 infrastructure for that is already there).
311 (for debugging purposes, etc.) on machines that are on the blacklist, set the
312 kernel environment variable
313 .Va hint.acpi.0.disabled
315 Before trying this, consider updating your BIOS to a more recent version that
316 may be compatible with ACPI.
320 driver completely, set the kernel environment variable
321 .Va hint.acpi.0.disabled
324 Some i386 machines totally fail to operate with some or all of ACPI disabled.
325 Other i386 machines fail with ACPI enabled.
326 Disabling all or part of ACPI on non-i386 platforms (i.e., platforms where
327 ACPI support is mandatory) may result in a non-functional system.
331 driver comprises a set of drivers, which may be selectively disabled
333 To disable a sub-driver, list it in the kernel
335 .Va debug.acpi.disabled .
336 Multiple entries can be listed, separated by a space.
338 ACPI sub-devices and features that can be disabled:
339 .Bl -tag -width ".Li sysresource"
341 Disable all ACPI features and devices.
347 Probes and attaches subdevices.
348 Disabling will avoid scanning the ACPI namespace entirely.
351 Attaches standard ACPI sub-drivers and devices enumerated in the
353 Disabling this has a similar effect to disabling
356 ACPI namespace will still be scanned.
359 Supports ACPI button devices (typically power and sleep buttons).
362 Control-method batteries device.
365 Supports CPU power-saving and speed-setting functions.
368 Supports the ACPI Embedded Controller interface, used to communicate
369 with embedded platform controllers.
372 Supports an ISA bus bridge defined in the ACPI namespace,
373 typically as a child of a PCI bus.
376 Supports an ACPI laptop lid switch, which typically puts a
380 Do not ask firmware for available x86-vendor specific methods to enter
383 Only query and use the generic I/O-based entrance method.
384 The knob is provided to work around inconsistencies in the tables
389 Quirks automatically disable ACPI functionality based on the XSDT table's
390 OEM vendor name and revision date.
393 Supports Host to PCI bridges.
396 Performs PCI interrupt routing.
399 Pseudo-devices containing resources which ACPI claims.
402 Supports system cooling and heat management.
405 Implements a timecounter using the ACPI fixed-frequency timer.
410 which may conflict with
415 It is also possible to avoid portions of the ACPI namespace which
416 may be causing problems, by listing the full path of the root of
417 the region to be avoided in the kernel environment variable
418 .Va debug.acpi.avoid .
419 The object and all of its children will be ignored during the
420 bus/children scan of the namespace.
421 The ACPI CA code will still know about the avoided region.
423 To enable debugging output,
425 must be compiled with
426 .Cd "options ACPI_DEBUG" .
427 Debugging output is separated between layers and levels, where a layer is
428 a component of the ACPI subsystem, and a level is a particular kind
431 Both layers and levels are specified as a whitespace-separated list of
432 tokens, with layers listed in
435 .Va debug.acpi.level .
437 The first set of layers is for ACPI-CA components, and the second is for
440 The ACPI-CA layer descriptions include the prefix for the files they
442 The supported layers are:
444 .Bl -tag -compact -width ".Li ACPI_CA_DISASSEMBLER"
445 .It Li ACPI_UTILITIES
446 Utility ("ut") functions
448 Hardware access ("hw")
453 .It Li ACPI_NAMESPACE
454 Namespace evaluation ("ns")
457 .It Li ACPI_DISPATCHER
458 Internal representation of interpreter state ("ds")
460 Execute AML methods ("ex")
461 .It Li ACPI_RESOURCES
462 Resource parsing ("rs")
463 .It Li ACPI_CA_DEBUGGER
464 Debugger implementation ("db", "dm")
465 .It Li ACPI_OS_SERVICES
466 Usermode support routines ("os")
467 .It Li ACPI_CA_DISASSEMBLER
468 Disassembler implementation (unused)
469 .It Li ACPI_ALL_COMPONENTS
470 All the above ACPI-CA components
471 .It Li ACPI_AC_ADAPTER
474 Control-method battery driver
476 ACPI, ISA, and PCI bus drivers
478 Power and sleep button driver
480 Embedded controller driver
484 Platform-specific driver for hotkeys, LED, etc.
486 Power resource driver
487 .It Li ACPI_PROCESSOR
493 .It Li ACPI_ALL_DRIVERS
499 The supported levels are:
501 .Bl -tag -compact -width ".Li ACPI_LV_AML_DISASSEMBLE"
503 Initialization progress
504 .It Li ACPI_LV_DEBUG_OBJECT
507 General information and progress
508 .It Li ACPI_LV_REPAIR
509 Repair a common problem with predefined methods
510 .It Li ACPI_LV_ALL_EXCEPTIONS
511 All the previous levels
513 .It Li ACPI_LV_DISPATCH
516 .It Li ACPI_LV_OPREGION
517 .It Li ACPI_LV_BFIELD
518 .It Li ACPI_LV_TABLES
519 .It Li ACPI_LV_VALUES
520 .It Li ACPI_LV_OBJECTS
521 .It Li ACPI_LV_RESOURCES
522 .It Li ACPI_LV_USER_REQUESTS
523 .It Li ACPI_LV_PACKAGE
524 .It Li ACPI_LV_VERBOSITY1
525 All the previous levels
526 .It Li ACPI_LV_ALLOCATIONS
527 .It Li ACPI_LV_FUNCTIONS
528 .It Li ACPI_LV_OPTIMIZATIONS
529 .It Li ACPI_LV_VERBOSITY2
530 All the previous levels
533 .Qq Li ACPI_LV_VERBOSITY2
535 .It Li ACPI_LV_THREADS
537 .It Li ACPI_LV_INTERRUPTS
538 .It Li ACPI_LV_VERBOSITY3
539 All the previous levels
540 .It Li ACPI_LV_AML_DISASSEMBLE
541 .It Li ACPI_LV_VERBOSE_INFO
542 .It Li ACPI_LV_FULL_TABLES
543 .It Li ACPI_LV_EVENTS
544 .It Li ACPI_LV_VERBOSE
546 .Qq Li ACPI_LV_VERBOSITY3
547 .It Li ACPI_LV_INIT_NAMES
551 Selection of the appropriate layer and level values is important
552 to avoid massive amounts of debugging output.
553 For example, the following configuration is a good way to gather initial
555 It enables debug output for both ACPI-CA and the
557 driver, printing basic information about errors, warnings, and progress.
558 .Bd -literal -offset indent
559 debug.acpi.layer="ACPI_ALL_COMPONENTS ACPI_ALL_DRIVERS"
560 debug.acpi.level="ACPI_LV_ALL_EXCEPTIONS"
563 Debugging output by the ACPI CA subsystem is prefixed with the
564 module name in lowercase, followed by a source line number.
567 code follows the same format, but
568 the module name is uppercased.
569 .Sh OVERRIDING YOUR BIOS BYTECODE
570 ACPI interprets bytecode named AML
571 (ACPI Machine Language)
572 provided by the BIOS vendor as a memory image at boot time.
573 Sometimes, the AML code contains a bug that does not appear when parsed
574 by the Microsoft implementation.
576 provides a way to override it with your own AML code to work around
577 or debug such problems.
578 Note that all AML in your DSDT and any SSDT tables is overridden.
580 In order to load your AML code, you must edit
581 .Pa /boot/loader.conf
582 and include the following lines.
583 .Bd -literal -offset indent
585 acpi_dsdt_name="/boot/acpi_dsdt.aml" # You may change this name.
588 In order to prepare your AML code, you will need the
592 utilities and some ACPI knowledge.
594 ACPI is only found and supported on i386/ia32 and amd64.
605 .%A "Compaq Computer Corporation"
606 .%A "Intel Corporation"
607 .%A "Microsoft Corporation"
608 .%A "Phoenix Technologies Ltd."
609 .%A "Toshiba Corporation"
611 .%T "Advanced Configuration and Power Interface Specification"
612 .%U http://acpi.info/spec.htm
616 The ACPI CA subsystem is developed and maintained by
617 Intel Architecture Labs.
619 The following people made notable contributions to the ACPI subsystem
623 .An Takanori Watanabe Aq Mt takawata@jp.FreeBSD.org ,
624 .An Mitsuru IWASAKI Aq Mt iwasaki@jp.FreeBSD.org ,
625 .An Munehiro Matsuda ,
627 the ACPI-jp mailing list at
628 .Aq Mt acpi-jp@jp.FreeBSD.org ,
629 and many other contributors.
631 This manual page was written by
632 .An Michael Smith Aq Mt msmith@FreeBSD.org .
634 Many BIOS versions have serious bugs that may cause system instability,
635 break suspend/resume, or prevent devices from operating properly due to
636 IRQ routing problems.
637 Upgrade your BIOS to the latest version available from the vendor before
638 deciding it is a problem with