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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
58 before booting the kernel.
60 Debugging is separated between layers and levels, where a layer is
61 a portion of the ACPI subsystem, and a level is a particular kind
64 Both layers and levels are specified as a whitespace-separated list of
65 tokens, with layers listed in
68 .Va debug.acpi.level .
69 The supported layers are:
71 .Bl -item -offset indent -compact
95 .Li ACPI_CA_DISASSEMBLER
97 .Li ACPI_ALL_COMPONENTS
122 The supported levels are:
124 .Bl -item -offset indent -compact
132 .Li ACPI_LV_DEBUG_OBJECT
136 .Li ACPI_LV_ALL_EXCEPTIONS
138 .Li ACPI_LV_INIT_NAMES
160 .Li ACPI_LV_RESOURCES
162 .Li ACPI_LV_USER_REQUESTS
166 .Li ACPI_LV_VERBOSITY1
168 .Li ACPI_LV_ALLOCATIONS
170 .Li ACPI_LV_FUNCTIONS
172 .Li ACPI_LV_OPTIMIZATIONS
174 .Li ACPI_LV_VERBOSITY2
184 .Li ACPI_LV_INTERRUPTS
186 .Li ACPI_LV_VERBOSITY3
188 .Li ACPI_LV_AML_DISASSEMBLE
190 .Li ACPI_LV_VERBOSE_INFO
192 .Li ACPI_LV_FULL_TABLES
199 Selection of the appropriate layer and level values is important
200 to avoid massive amounts of debugging output.
201 Check the code to see which you need.
203 Debugging output by the ACPI CA subsystem is prefixed with the
204 module name in lowercase, followed by a source line number.
207 code follows the same format, but
208 the module name is uppercased.
212 driver completely, set the kernel environment variable
213 .Va hint.acpi.0.disabled
215 Some i386 machines totally fail to operate with some or all of ACPI disabled.
216 Other i386 machines fail with ACPI enabled.
217 Non-i386 platforms do not support operating systems which do not use ACPI.
218 Disabling all or part of ACPI on non-i386 platforms may result in a
219 non-functional system.
223 driver comprises a set of drivers, which may be selectively disabled
225 To disable a sub-driver, list it in the kernel
227 .Va debug.acpi.disable .
229 ACPI sub-devices and features that can be disabled:
230 .Bl -tag -width children
233 Probes and attaches subdevices.
234 Disabling will avoid scanning the ACPI namespace entirely.
237 Attaches standard ACPI sub-drivers and devices enumerated in the
239 Disabling this has a similar effect to disabling
242 ACPI namespace will still be scanned.
245 Supports ACPI button devices (typically power and sleep buttons).
248 Supports the ACPI Embedded Controller interface, used to
249 communicate with embedded platform controllers.
252 Supports an ISA bus bridge defined in the ACPI namespace,
253 typically as a child of a PCI bus.
256 Supports an ACPI laptop lid switch, which typically puts a
260 Supports Host to PCI bridges.
263 Supports CPU power-saving and speed-setting functions.
266 Supports system cooling and heat management.
269 Implements a timecounter using the ACPI fixed-frequency timer.
272 It is also possible to avoid portions of the ACPI namespace which
273 may be causing problems, by listing the full path of the root of
274 the region to be avoided in the kernel environment variable
275 .Va debug.acpi.avoid .
276 The object and all of its children will be ignored during the
277 bus/children scan of the namespace.
278 The ACPI CA code will still
279 know about the avoided region.
280 .Sh OVERRIDING YOUR BIOS BYTECODE
281 ACPI interprets bytecode named AML, ACPI Machine Language, provided by the BIOS
282 vendor as a memory image at boot time.
283 Sometimes, the AML code contains
284 a problem that does not appear in the Microsoft implementation.
285 So we provide a way to override it with your own AML code.
287 In order to load your AML code,
289 .Pa /boot/loader.conf
291 include the following lines.
292 .Bd -literal -offset indent
294 acpi_dsdt_name="/boot/acpi_dsdt.aml" #You may change the name.
297 In order to prepare your AML code, you will need the
301 utilities and some ACPI knowledge.
303 .Bl -tag -width indent
304 .It Va acpi_dsdt_load
305 Enables loading of a custom ACPI DSDT.
306 .It Va acpi_dsdt_name
307 Name of the DSDT table to load, if loading is enabled.
308 .It Va debug.acpi.disable
309 Selectively disables portions of ACPI for debugging purposes.
310 .It Va hint.acpi.0.disabled
311 Disables all of ACPI.
312 .It Va hw.acpi.ec.poll_timeout
313 Delay in milliseconds to wait for the EC to respond.
314 Try increasing this number if you get the error
315 .Er AE_NO_HARDWARE_RESPONSE .
316 .It Va hw.acpi.reset_video
317 Enables calling the VESA reset BIOS vector on the resume path.
318 Some graphic chips have problems such as LCD white-out after resume.
319 Try setting this to 0 if this causes problems for you.
320 .It Va hw.acpi.osname
321 Some systems' ASL may have problems because they look for names
322 of Microsoft operating systems.
323 This tunable overrides the value of the
325 object from its default of
327 .It Va hw.acpi.pci.link.%d.%d.%d.irq
328 Override the interrupt to use.
329 .It Va hw.acpi.verbose
330 Turn on verbose debugging information about what ACPI is doing.
333 .Bl -tag -width indent
334 .It Va hw.acpi.cpu.throttle_max
335 Maximum value for CPU throttling, equal to 100% of the clock rate.
336 .It Va hw.acpi.cpu.throttle_state
337 Get or set the current throttling state, from 1 to
338 .Va hw.acpi.cpu.throttle_max .
339 This scales back the CPU clock rate and the corresponding power consumption.
340 .It Va hw.acpi.cpu.cx_history
341 Debugging information listing all sleep states and the number of
342 long and short sleeps for each one.
343 The counters are reset when
344 .Va hw.acpi.cpu.cx_lowest
346 .It Va hw.acpi.cpu.cx_lowest
347 Zero-based index of the lowest CPU idle state to use.
348 A scheduling algorithm will select between 0...index for the state
349 to use during the next sleep.
350 To enable ACPI CPU idling control,
351 .Va machdep.cpu_idle_hlt
353 .It Va hw.acpi.cpu.cx_supported
354 List of supported CPU idle states and their transition latency
356 Each state has a type, C1-3.
357 C1 is equivalent to the ia32 HLT instruction, C2 provides a deeper
358 sleep with the same semantics, and C3 provides the deepest sleep
359 but additionally requires bus mastering to be disabled.
360 Deeper sleeps provide more power savings but increased transition
361 latency when an interrupt occurs.
364 ACPI is only found and supported on i386/ia32, ia64, and amd64.
373 .%A "Compaq Computer Corporation"
374 .%A "Intel Corporation"
375 .%A "Microsoft Corporation"
376 .%A "Phoenix Technologies Ltd."
377 .%A "Toshiba Corporation"
379 .%T "Advanced Configuration and Power Interface Specification"
380 .%O http://acpi.info/spec.htm
384 The ACPI CA subsystem is developed and maintained by
385 Intel Architecture Labs.
387 The following people made notable contributions to the ACPI subsystem
391 .An Takanori Watanabe Aq takawata@jp.FreeBSD.org ,
392 .An Mitsuru IWASAKI Aq iwasaki@jp.FreeBSD.org ,
393 .An Munehiro Matsuda ,
395 the ACPI-jp mailing list at
396 .Aq acpi-jp@jp.FreeBSD.org ,
397 and many other contributors.
399 This manual page was written by
400 .An Michael Smith Aq msmith@FreeBSD.org .
404 driver is loaded as a module when it is already linked as part of the
405 kernel, odd things may happen.