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Al Stone735f00b2015-03-24 14:02:55 +00001ACPI Tables
2-----------
3The expectations of individual ACPI tables are discussed in the list that
4follows.
5
6If a section number is used, it refers to a section number in the ACPI
7specification where the object is defined. If "Signature Reserved" is used,
8the table signature (the first four bytes of the table) is the only portion
9of the table recognized by the specification, and the actual table is defined
10outside of the UEFI Forum (see Section 5.2.6 of the specification).
11
12For ACPI on arm64, tables also fall into the following categories:
13
14 -- Required: DSDT, FADT, GTDT, MADT, MCFG, RSDP, SPCR, XSDT
15
16 -- Recommended: BERT, EINJ, ERST, HEST, SSDT
17
18 -- Optional: BGRT, CPEP, CSRT, DRTM, ECDT, FACS, FPDT, MCHI, MPST,
19 MSCT, RASF, SBST, SLIT, SPMI, SRAT, TCPA, TPM2, UEFI
20
21 -- Not supported: BOOT, DBG2, DBGP, DMAR, ETDT, HPET, IBFT, IVRS,
22 LPIT, MSDM, RSDT, SLIC, WAET, WDAT, WDRT, WPBT
23
24
25Table Usage for ARMv8 Linux
26----- ----------------------------------------------------------------
27BERT Section 18.3 (signature == "BERT")
28 == Boot Error Record Table ==
29 Must be supplied if RAS support is provided by the platform. It
30 is recommended this table be supplied.
31
32BOOT Signature Reserved (signature == "BOOT")
33 == simple BOOT flag table ==
34 Microsoft only table, will not be supported.
35
36BGRT Section 5.2.22 (signature == "BGRT")
37 == Boot Graphics Resource Table ==
38 Optional, not currently supported, with no real use-case for an
39 ARM server.
40
41CPEP Section 5.2.18 (signature == "CPEP")
42 == Corrected Platform Error Polling table ==
43 Optional, not currently supported, and not recommended until such
44 time as ARM-compatible hardware is available, and the specification
45 suitably modified.
46
47CSRT Signature Reserved (signature == "CSRT")
48 == Core System Resources Table ==
49 Optional, not currently supported.
50
51DBG2 Signature Reserved (signature == "DBG2")
52 == DeBuG port table 2 ==
53 Microsoft only table, will not be supported.
54
55DBGP Signature Reserved (signature == "DBGP")
56 == DeBuG Port table ==
57 Microsoft only table, will not be supported.
58
59DSDT Section 5.2.11.1 (signature == "DSDT")
60 == Differentiated System Description Table ==
61 A DSDT is required; see also SSDT.
62
63 ACPI tables contain only one DSDT but can contain one or more SSDTs,
64 which are optional. Each SSDT can only add to the ACPI namespace,
65 but cannot modify or replace anything in the DSDT.
66
67DMAR Signature Reserved (signature == "DMAR")
68 == DMA Remapping table ==
69 x86 only table, will not be supported.
70
71DRTM Signature Reserved (signature == "DRTM")
72 == Dynamic Root of Trust for Measurement table ==
73 Optional, not currently supported.
74
75ECDT Section 5.2.16 (signature == "ECDT")
76 == Embedded Controller Description Table ==
77 Optional, not currently supported, but could be used on ARM if and
78 only if one uses the GPE_BIT field to represent an IRQ number, since
79 there are no GPE blocks defined in hardware reduced mode. This would
80 need to be modified in the ACPI specification.
81
82EINJ Section 18.6 (signature == "EINJ")
83 == Error Injection table ==
84 This table is very useful for testing platform response to error
85 conditions; it allows one to inject an error into the system as
86 if it had actually occurred. However, this table should not be
87 shipped with a production system; it should be dynamically loaded
88 and executed with the ACPICA tools only during testing.
89
90ERST Section 18.5 (signature == "ERST")
91 == Error Record Serialization Table ==
92 On a platform supports RAS, this table must be supplied if it is not
93 UEFI-based; if it is UEFI-based, this table may be supplied. When this
94 table is not present, UEFI run time service will be utilized to save
95 and retrieve hardware error information to and from a persistent store.
96
97ETDT Signature Reserved (signature == "ETDT")
98 == Event Timer Description Table ==
99 Obsolete table, will not be supported.
100
101FACS Section 5.2.10 (signature == "FACS")
102 == Firmware ACPI Control Structure ==
103 It is unlikely that this table will be terribly useful. If it is
104 provided, the Global Lock will NOT be used since it is not part of
105 the hardware reduced profile, and only 64-bit address fields will
106 be considered valid.
107
108FADT Section 5.2.9 (signature == "FACP")
109 == Fixed ACPI Description Table ==
110 Required for arm64.
111
112 The HW_REDUCED_ACPI flag must be set. All of the fields that are
113 to be ignored when HW_REDUCED_ACPI is set are expected to be set to
114 zero.
115
116 If an FACS table is provided, the X_FIRMWARE_CTRL field is to be
117 used, not FIRMWARE_CTRL.
118
119 If PSCI is used (as is recommended), make sure that ARM_BOOT_ARCH is
120 filled in properly -- that the PSCI_COMPLIANT flag is set and that
121 PSCI_USE_HVC is set or unset as needed (see table 5-37).
122
123 For the DSDT that is also required, the X_DSDT field is to be used,
124 not the DSDT field.
125
126FPDT Section 5.2.23 (signature == "FPDT")
127 == Firmware Performance Data Table ==
128 Optional, not currently supported.
129
130GTDT Section 5.2.24 (signature == "GTDT")
131 == Generic Timer Description Table ==
132 Required for arm64.
133
134HEST Section 18.3.2 (signature == "HEST")
135 == Hardware Error Source Table ==
136 Until further error source types are defined, use only types 6 (AER
137 Root Port), 7 (AER Endpoint), 8 (AER Bridge), or 9 (Generic Hardware
138 Error Source). Firmware first error handling is possible if and only
139 if Trusted Firmware is being used on arm64.
140
141 Must be supplied if RAS support is provided by the platform. It
142 is recommended this table be supplied.
143
144HPET Signature Reserved (signature == "HPET")
145 == High Precision Event timer Table ==
146 x86 only table, will not be supported.
147
148IBFT Signature Reserved (signature == "IBFT")
149 == iSCSI Boot Firmware Table ==
150 Microsoft defined table, support TBD.
151
152IVRS Signature Reserved (signature == "IVRS")
153 == I/O Virtualization Reporting Structure ==
154 x86_64 (AMD) only table, will not be supported.
155
156LPIT Signature Reserved (signature == "LPIT")
157 == Low Power Idle Table ==
158 x86 only table as of ACPI 5.1; future versions have been adapted for
159 use with ARM and will be recommended in order to support ACPI power
160 management.
161
162MADT Section 5.2.12 (signature == "APIC")
163 == Multiple APIC Description Table ==
164 Required for arm64. Only the GIC interrupt controller structures
165 should be used (types 0xA - 0xE).
166
167MCFG Signature Reserved (signature == "MCFG")
168 == Memory-mapped ConFiGuration space ==
169 If the platform supports PCI/PCIe, an MCFG table is required.
170
171MCHI Signature Reserved (signature == "MCHI")
172 == Management Controller Host Interface table ==
173 Optional, not currently supported.
174
175MPST Section 5.2.21 (signature == "MPST")
176 == Memory Power State Table ==
177 Optional, not currently supported.
178
179MSDM Signature Reserved (signature == "MSDM")
180 == Microsoft Data Management table ==
181 Microsoft only table, will not be supported.
182
183MSCT Section 5.2.19 (signature == "MSCT")
184 == Maximum System Characteristic Table ==
185 Optional, not currently supported.
186
187RASF Section 5.2.20 (signature == "RASF")
188 == RAS Feature table ==
189 Optional, not currently supported.
190
191RSDP Section 5.2.5 (signature == "RSD PTR")
192 == Root System Description PoinTeR ==
193 Required for arm64.
194
195RSDT Section 5.2.7 (signature == "RSDT")
196 == Root System Description Table ==
197 Since this table can only provide 32-bit addresses, it is deprecated
198 on arm64, and will not be used.
199
200SBST Section 5.2.14 (signature == "SBST")
201 == Smart Battery Subsystem Table ==
202 Optional, not currently supported.
203
204SLIC Signature Reserved (signature == "SLIC")
205 == Software LIcensing table ==
206 Microsoft only table, will not be supported.
207
208SLIT Section 5.2.17 (signature == "SLIT")
209 == System Locality distance Information Table ==
210 Optional in general, but required for NUMA systems.
211
212SPCR Signature Reserved (signature == "SPCR")
213 == Serial Port Console Redirection table ==
214 Required for arm64.
215
216SPMI Signature Reserved (signature == "SPMI")
217 == Server Platform Management Interface table ==
218 Optional, not currently supported.
219
220SRAT Section 5.2.16 (signature == "SRAT")
221 == System Resource Affinity Table ==
222 Optional, but if used, only the GICC Affinity structures are read.
223 To support NUMA, this table is required.
224
225SSDT Section 5.2.11.2 (signature == "SSDT")
226 == Secondary System Description Table ==
227 These tables are a continuation of the DSDT; these are recommended
228 for use with devices that can be added to a running system, but can
229 also serve the purpose of dividing up device descriptions into more
230 manageable pieces.
231
232 An SSDT can only ADD to the ACPI namespace. It cannot modify or
233 replace existing device descriptions already in the namespace.
234
235 These tables are optional, however. ACPI tables should contain only
236 one DSDT but can contain many SSDTs.
237
238TCPA Signature Reserved (signature == "TCPA")
239 == Trusted Computing Platform Alliance table ==
240 Optional, not currently supported, and may need changes to fully
241 interoperate with arm64.
242
243TPM2 Signature Reserved (signature == "TPM2")
244 == Trusted Platform Module 2 table ==
245 Optional, not currently supported, and may need changes to fully
246 interoperate with arm64.
247
248UEFI Signature Reserved (signature == "UEFI")
249 == UEFI ACPI data table ==
250 Optional, not currently supported. No known use case for arm64,
251 at present.
252
253WAET Signature Reserved (signature == "WAET")
254 == Windows ACPI Emulated devices Table ==
255 Microsoft only table, will not be supported.
256
257WDAT Signature Reserved (signature == "WDAT")
258 == Watch Dog Action Table ==
259 Microsoft only table, will not be supported.
260
261WDRT Signature Reserved (signature == "WDRT")
262 == Watch Dog Resource Table ==
263 Microsoft only table, will not be supported.
264
265WPBT Signature Reserved (signature == "WPBT")
266 == Windows Platform Binary Table ==
267 Microsoft only table, will not be supported.
268
269XSDT Section 5.2.8 (signature == "XSDT")
270 == eXtended System Description Table ==
271 Required for arm64.
272
273
274ACPI Objects
275------------
276The expectations on individual ACPI objects are discussed in the list that
277follows:
278
279Name Section Usage for ARMv8 Linux
280---- ------------ -------------------------------------------------
281_ADR 6.1.1 Use as needed.
282
283_BBN 6.5.5 Use as needed; PCI-specific.
284
285_BDN 6.5.3 Optional; not likely to be used on arm64.
286
287_CCA 6.2.17 This method should be defined for all bus masters
288 on arm64. While cache coherency is assumed, making
289 it explicit ensures the kernel will set up DMA as
290 it should.
291
292_CDM 6.2.1 Optional, to be used only for processor devices.
293
294_CID 6.1.2 Use as needed.
295
296_CLS 6.1.3 Use as needed.
297
298_CRS 6.2.2 Required on arm64.
299
300_DCK 6.5.2 Optional; not likely to be used on arm64.
301
302_DDN 6.1.4 This field can be used for a device name. However,
303 it is meant for DOS device names (e.g., COM1), so be
304 careful of its use across OSes.
305
306_DEP 6.5.8 Use as needed.
307
308_DIS 6.2.3 Optional, for power management use.
309
310_DLM 5.7.5 Optional.
311
312_DMA 6.2.4 Optional.
313
314_DSD 6.2.5 To be used with caution. If this object is used, try
315 to use it within the constraints already defined by the
316 Device Properties UUID. Only in rare circumstances
317 should it be necessary to create a new _DSD UUID.
318
319 In either case, submit the _DSD definition along with
320 any driver patches for discussion, especially when
321 device properties are used. A driver will not be
322 considered complete without a corresponding _DSD
323 description. Once approved by kernel maintainers,
324 the UUID or device properties must then be registered
325 with the UEFI Forum; this may cause some iteration as
326 more than one OS will be registering entries.
327
328_DSM Do not use this method. It is not standardized, the
329 return values are not well documented, and it is
330 currently a frequent source of error.
331
332_DSW 7.2.1 Use as needed; power management specific.
333
334_EDL 6.3.1 Optional.
335
336_EJD 6.3.2 Optional.
337
338_EJx 6.3.3 Optional.
339
340_FIX 6.2.7 x86 specific, not used on arm64.
341
342\_GL 5.7.1 This object is not to be used in hardware reduced
343 mode, and therefore should not be used on arm64.
344
345_GLK 6.5.7 This object requires a global lock be defined; there
346 is no global lock on arm64 since it runs in hardware
347 reduced mode. Hence, do not use this object on arm64.
348
349\_GPE 5.3.1 This namespace is for x86 use only. Do not use it
350 on arm64.
351
352_GSB 6.2.7 Optional.
353
354_HID 6.1.5 Use as needed. This is the primary object to use in
355 device probing, though _CID and _CLS may also be used.
356
357_HPP 6.2.8 Optional, PCI specific.
358
359_HPX 6.2.9 Optional, PCI specific.
360
361_HRV 6.1.6 Optional, use as needed to clarify device behavior; in
362 some cases, this may be easier to use than _DSD.
363
364_INI 6.5.1 Not required, but can be useful in setting up devices
365 when UEFI leaves them in a state that may not be what
366 the driver expects before it starts probing.
367
368_IRC 7.2.15 Use as needed; power management specific.
369
370_LCK 6.3.4 Optional.
371
372_MAT 6.2.10 Optional; see also the MADT.
373
374_MLS 6.1.7 Optional, but highly recommended for use in
375 internationalization.
376
377_OFF 7.1.2 It is recommended to define this method for any device
378 that can be turned on or off.
379
380_ON 7.1.3 It is recommended to define this method for any device
381 that can be turned on or off.
382
383\_OS 5.7.3 This method will return "Linux" by default (this is
384 the value of the macro ACPI_OS_NAME on Linux). The
385 command line parameter acpi_os=<string> can be used
386 to set it to some other value.
387
388_OSC 6.2.11 This method can be a global method in ACPI (i.e.,
389 \_SB._OSC), or it may be associated with a specific
390 device (e.g., \_SB.DEV0._OSC), or both. When used
391 as a global method, only capabilities published in
392 the ACPI specification are allowed. When used as
393 a device-specific method, the process described for
394 using _DSD MUST be used to create an _OSC definition;
395 out-of-process use of _OSC is not allowed. That is,
396 submit the device-specific _OSC usage description as
397 part of the kernel driver submission, get it approved
398 by the kernel community, then register it with the
399 UEFI Forum.
400
401\_OSI 5.7.2 Deprecated on ARM64. Any invocation of this method
402 will print a warning on the console and return false.
403 That is, as far as ACPI firmware is concerned, _OSI
404 cannot be used to determine what sort of system is
405 being used or what functionality is provided. The
406 _OSC method is to be used instead.
407
408_OST 6.3.5 Optional.
409
410_PDC 8.4.1 Deprecated, do not use on arm64.
411
412\_PIC 5.8.1 The method should not be used. On arm64, the only
413 interrupt model available is GIC.
414
415_PLD 6.1.8 Optional.
416
417\_PR 5.3.1 This namespace is for x86 use only on legacy systems.
418 Do not use it on arm64.
419
420_PRS 6.2.12 Optional.
421
422_PRT 6.2.13 Required as part of the definition of all PCI root
423 devices.
424
425_PRW 7.2.13 Use as needed; power management specific.
426
427_PRx 7.2.8-11 Use as needed; power management specific. If _PR0 is
428 defined, _PR3 must also be defined.
429
430_PSC 7.2.6 Use as needed; power management specific.
431
432_PSE 7.2.7 Use as needed; power management specific.
433
434_PSW 7.2.14 Use as needed; power management specific.
435
436_PSx 7.2.2-5 Use as needed; power management specific. If _PS0 is
437 defined, _PS3 must also be defined. If clocks or
438 regulators need adjusting to be consistent with power
439 usage, change them in these methods.
440
441\_PTS 7.3.1 Use as needed; power management specific.
442
443_PXM 6.2.14 Optional.
444
445_REG 6.5.4 Use as needed.
446
447\_REV 5.7.4 Always returns the latest version of ACPI supported.
448
449_RMV 6.3.6 Optional.
450
451\_SB 5.3.1 Required on arm64; all devices must be defined in this
452 namespace.
453
454_SEG 6.5.6 Use as needed; PCI-specific.
455
456\_SI 5.3.1, Optional.
457 9.1
458
459_SLI 6.2.15 Optional; recommended when SLIT table is in use.
460
461_STA 6.3.7, It is recommended to define this method for any device
462 7.1.4 that can be turned on or off.
463
464_SRS 6.2.16 Optional; see also _PRS.
465
466_STR 6.1.10 Recommended for conveying device names to end users;
467 this is preferred over using _DDN.
468
469_SUB 6.1.9 Use as needed; _HID or _CID are preferred.
470
471_SUN 6.1.11 Optional.
472
473\_Sx 7.3.2 Use as needed; power management specific.
474
475_SxD 7.2.16-19 Use as needed; power management specific.
476
477_SxW 7.2.20-24 Use as needed; power management specific.
478
479_SWS 7.3.3 Use as needed; power management specific; this may
480 require specification changes for use on arm64.
481
482\_TTS 7.3.4 Use as needed; power management specific.
483
484\_TZ 5.3.1 Optional.
485
486_UID 6.1.12 Recommended for distinguishing devices of the same
487 class; define it if at all possible.
488
489\_WAK 7.3.5 Use as needed; power management specific.
490
491
492ACPI Event Model
493----------------
494Do not use GPE block devices; these are not supported in the hardware reduced
495profile used by arm64. Since there are no GPE blocks defined for use on ARM
496platforms, GPIO-signaled interrupts should be used for creating system events.
497
498
499ACPI Processor Control
500----------------------
501Section 8 of the ACPI specification is currently undergoing change that
502should be completed in the 6.0 version of the specification. Processor
503performance control will be handled differently for arm64 at that point
504in time. Processor aggregator devices (section 8.5) will not be used,
505for example, but another similar mechanism instead.
506
507While UEFI constrains what we can say until the release of 6.0, it is
508recommended that CPPC (8.4.5) be used as the primary model. This will
509still be useful into the future. C-states and P-states will still be
510provided, but most of the current design work appears to favor CPPC.
511
512Further, it is essential that the ARMv8 SoC provide a fully functional
513implementation of PSCI; this will be the only mechanism supported by ACPI
514to control CPU power state (including secondary CPU booting).
515
516More details will be provided on the release of the ACPI 6.0 specification.
517
518
519ACPI System Address Map Interfaces
520----------------------------------
521In Section 15 of the ACPI specification, several methods are mentioned as
522possible mechanisms for conveying memory resource information to the kernel.
523For arm64, we will only support UEFI for booting with ACPI, hence the UEFI
524GetMemoryMap() boot service is the only mechanism that will be used.
525
526
527ACPI Platform Error Interfaces (APEI)
528-------------------------------------
529The APEI tables supported are described above.
530
531APEI requires the equivalent of an SCI and an NMI on ARMv8. The SCI is used
532to notify the OSPM of errors that have occurred but can be corrected and the
533system can continue correct operation, even if possibly degraded. The NMI is
534used to indicate fatal errors that cannot be corrected, and require immediate
535attention.
536
537Since there is no direct equivalent of the x86 SCI or NMI, arm64 handles
538these slightly differently. The SCI is handled as a normal GPIO-signaled
539interrupt; given that these are corrected (or correctable) errors being
540reported, this is sufficient. The NMI is emulated as the highest priority
541GPIO-signaled interrupt possible. This implies some caution must be used
542since there could be interrupts at higher privilege levels or even interrupts
543at the same priority as the emulated NMI. In Linux, this should not be the
544case but one should be aware it could happen.
545
546
547ACPI Objects Not Supported on ARM64
548-----------------------------------
549While this may change in the future, there are several classes of objects
550that can be defined, but are not currently of general interest to ARM servers.
551
552These are not supported:
553
554 -- Section 9.2: ambient light sensor devices
555
556 -- Section 9.3: battery devices
557
558 -- Section 9.4: lids (e.g., laptop lids)
559
560 -- Section 9.8.2: IDE controllers
561
562 -- Section 9.9: floppy controllers
563
564 -- Section 9.10: GPE block devices
565
566 -- Section 9.15: PC/AT RTC/CMOS devices
567
568 -- Section 9.16: user presence detection devices
569
570 -- Section 9.17: I/O APIC devices; all GICs must be enumerable via MADT
571
572 -- Section 9.18: time and alarm devices (see 9.15)
573
574
575ACPI Objects Not Yet Implemented
576--------------------------------
577While these objects have x86 equivalents, and they do make some sense in ARM
578servers, there is either no hardware available at present, or in some cases
579there may not yet be a non-ARM implementation. Hence, they are currently not
580implemented though that may change in the future.
581
582Not yet implemented are:
583
584 -- Section 10: power source and power meter devices
585
586 -- Section 11: thermal management
587
588 -- Section 12: embedded controllers interface
589
590 -- Section 13: SMBus interfaces
591
592 -- Section 17: NUMA support (prototypes have been submitted for
593 review)