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33 .Nd Advanced Configuration and Power Management support
37 .Cd "options ACPI_DEBUG"
41 driver provides support for the Intel/Microsoft/Compaq/Toshiba ACPI
43 This support includes platform hardware discovery (superseding the
44 PnP and PCI BIOS), as well as power management (superseding APM) and
46 ACPI core support is provided by the ACPI CA reference implementation
51 driver is automatically loaded by the bootloader, and should not normally
52 be compiled into the kernel.
54 This support is still experimental, and thus there are many debugging
55 and tuning options which are managed via the kernel environment.
56 Tunables can be set at the
58 prompt before booting the kernel or stored in
59 .Pa /boot/loader.conf .
61 Debugging is separated between layers and levels, where a layer is
62 a portion of the ACPI subsystem, and a level is a particular kind
65 Both layers and levels are specified as a whitespace-separated list of
66 tokens, with layers listed in
69 .Va debug.acpi.level .
70 The supported layers are:
72 .Bl -item -offset indent -compact
96 .Li ACPI_CA_DISASSEMBLER
98 .Li ACPI_ALL_COMPONENTS
123 The supported levels are:
125 .Bl -item -offset indent -compact
133 .Li ACPI_LV_DEBUG_OBJECT
137 .Li ACPI_LV_ALL_EXCEPTIONS
139 .Li ACPI_LV_INIT_NAMES
161 .Li ACPI_LV_RESOURCES
163 .Li ACPI_LV_USER_REQUESTS
167 .Li ACPI_LV_VERBOSITY1
169 .Li ACPI_LV_ALLOCATIONS
171 .Li ACPI_LV_FUNCTIONS
173 .Li ACPI_LV_OPTIMIZATIONS
175 .Li ACPI_LV_VERBOSITY2
185 .Li ACPI_LV_INTERRUPTS
187 .Li ACPI_LV_VERBOSITY3
189 .Li ACPI_LV_AML_DISASSEMBLE
191 .Li ACPI_LV_VERBOSE_INFO
193 .Li ACPI_LV_FULL_TABLES
200 Selection of the appropriate layer and level values is important
201 to avoid massive amounts of debugging output.
202 Check the code to see which you need.
204 Debugging output by the ACPI CA subsystem is prefixed with the
205 module name in lowercase, followed by a source line number.
208 code follows the same format, but
209 the module name is uppercased.
211 For machines known not to work with
213 enabled, there is a BIOS blacklist.
214 Currently, the blacklist only controls whether
216 should be disabled or not.
217 In the future, it will have more granularity to control features (the
218 infrastructure for that is already there).
222 (for debugging purposes, etc.) on machines that are on the blacklist, set the
223 kernel environment variable
224 .Va hint.acpi.0.disabled
226 Before trying this, consider updating your BIOS to a more recent version that
227 may be compatible with ACPI.
231 driver completely, set the kernel environment variable
232 .Va hint.acpi.0.disabled
235 Some i386 machines totally fail to operate with some or all of ACPI disabled.
236 Other i386 machines fail with ACPI enabled.
237 Non-i386 platforms do not support operating systems which do not use ACPI.
238 Disabling all or part of ACPI on non-i386 platforms may result in a
239 non-functional system.
243 driver comprises a set of drivers, which may be selectively disabled
245 To disable a sub-driver, list it in the kernel
247 .Va debug.acpi.disabled .
248 Multiple entries can be listed, separated by a space.
250 ACPI sub-devices and features that can be disabled:
251 .Bl -tag -width sysresource
253 Disable all ACPI features and devices.
259 Probes and attaches subdevices.
260 Disabling will avoid scanning the ACPI namespace entirely.
263 Attaches standard ACPI sub-drivers and devices enumerated in the
265 Disabling this has a similar effect to disabling
268 ACPI namespace will still be scanned.
271 Supports ACPI button devices (typically power and sleep buttons).
274 Control-method batteries device.
277 Supports CPU power-saving and speed-setting functions.
280 Supports the ACPI Embedded Controller interface, used to communicate
281 with embedded platform controllers.
284 Supports an ISA bus bridge defined in the ACPI namespace,
285 typically as a child of a PCI bus.
288 Supports an ACPI laptop lid switch, which typically puts a
293 Quirks automatically disable ACPI functionality based on the XSDT table's
294 OEM vendor name and revision date.
297 Supports Host to PCI bridges.
300 Performs PCI interrupt routing.
303 Pseudo-devices containing resources which ACPI claims.
306 Supports system cooling and heat management.
309 Implements a timecounter using the ACPI fixed-frequency timer.
312 It is also possible to avoid portions of the ACPI namespace which
313 may be causing problems, by listing the full path of the root of
314 the region to be avoided in the kernel environment variable
315 .Va debug.acpi.avoid .
316 The object and all of its children will be ignored during the
317 bus/children scan of the namespace.
318 The ACPI CA code will still
319 know about the avoided region.
320 .Sh OVERRIDING YOUR BIOS BYTECODE
321 ACPI interprets bytecode named AML, ACPI Machine Language, provided by the BIOS
322 vendor as a memory image at boot time.
323 Sometimes, the AML code contains
324 a problem that does not appear in the Microsoft implementation.
325 So we provide a way to override it with your own AML code.
327 In order to load your AML code,
329 .Pa /boot/loader.conf
331 include the following lines.
332 .Bd -literal -offset indent
334 acpi_dsdt_name="/boot/acpi_dsdt.aml" #You may change the name.
337 In order to prepare your AML code, you will need the
341 utilities and some ACPI knowledge.
343 .Bl -tag -width indent
344 .It Va acpi_dsdt_load
345 Enables loading of a custom ACPI DSDT.
346 .It Va acpi_dsdt_name
347 Name of the DSDT table to load, if loading is enabled.
348 .It Va debug.acpi.disabled
349 Selectively disables portions of ACPI for debugging purposes.
350 .It Va hint.acpi.0.disabled
351 Set this to 1 to disable all of ACPI.
352 If ACPI has been disabled on your system due to a blacklist entry for your
353 BIOS, you can set this to 0 to re-enable ACPI for testing.
354 .It Va hw.acpi.ec.poll_timeout
355 Delay in milliseconds to wait for the EC to respond.
356 Try increasing this number if you get the error
357 .Er AE_NO_HARDWARE_RESPONSE .
358 .It Va hw.acpi.reset_video
359 Enables calling the VESA reset BIOS vector on the resume path.
360 Some graphic chips have problems such as LCD white-out after resume.
361 Try setting this to 0 if this causes problems for you.
362 .It Va hw.acpi.osname
363 Some systems' ASL may have problems because they look for names
364 of Microsoft operating systems.
365 This tunable overrides the value of the
367 object from its default of
369 .It Va hw.acpi.pci.link.%d.%d.%d.irq
370 Override the interrupt to use.
371 .It Va hw.acpi.verbose
372 Turn on verbose debugging information about what ACPI is doing.
375 .Bl -tag -width indent
376 .It Va hw.acpi.cpu.throttle_max
377 Maximum value for CPU throttling, equal to 100% of the clock rate.
378 .It Va hw.acpi.cpu.throttle_state
379 Get or set the current throttling state, from 1 to
380 .Va hw.acpi.cpu.throttle_max .
381 This scales back the CPU clock rate and the corresponding power consumption.
382 .It Va hw.acpi.cpu.cx_usage
383 Debugging information listing the percent of total usage for each sleep state.
384 The values are reset when
385 .Va hw.acpi.cpu.cx_lowest
387 .It Va hw.acpi.cpu.cx_lowest
388 Lowest Cx state to use for idling the CPU.
389 A scheduling algorithm will select states between C1 and this setting
390 as system load dictates.
391 To enable ACPI CPU idling control,
392 .Va machdep.cpu_idle_hlt
394 .It Va hw.acpi.cpu.cx_supported
395 List of supported CPU idle states and their transition latency
397 Each state has a type (e.g., C2).
398 C1 is equivalent to the ia32 HLT instruction, C2 provides a deeper
399 sleep with the same semantics, and C3 provides the deepest sleep
400 but additionally requires bus mastering to be disabled.
401 States greater than C3 provide even more power savings with the same
402 semantics as the C3 state.
403 Deeper sleeps provide more power savings but increased transition
404 latency when an interrupt occurs.
407 ACPI is only found and supported on i386/ia32, ia64, and amd64.
418 .%A "Compaq Computer Corporation"
419 .%A "Intel Corporation"
420 .%A "Microsoft Corporation"
421 .%A "Phoenix Technologies Ltd."
422 .%A "Toshiba Corporation"
424 .%T "Advanced Configuration and Power Interface Specification"
425 .%O http://acpi.info/spec.htm
429 The ACPI CA subsystem is developed and maintained by
430 Intel Architecture Labs.
432 The following people made notable contributions to the ACPI subsystem
436 .An Takanori Watanabe Aq takawata@jp.FreeBSD.org ,
437 .An Mitsuru IWASAKI Aq iwasaki@jp.FreeBSD.org ,
438 .An Munehiro Matsuda ,
440 the ACPI-jp mailing list at
441 .Aq acpi-jp@jp.FreeBSD.org ,
442 and many other contributors.
444 This manual page was written by
445 .An Michael Smith Aq msmith@FreeBSD.org .
449 driver is loaded as a module when it is already linked as part of the
450 kernel, odd things may happen.