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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 | =========== ACPI Tables =========== The expectations of individual ACPI tables are discussed in the list that follows. If a section number is used, it refers to a section number in the ACPI specification where the object is defined. If "Signature Reserved" is used, the table signature (the first four bytes of the table) is the only portion of the table recognized by the specification, and the actual table is defined outside of the UEFI Forum (see Section 5.2.6 of the specification). For ACPI on arm64, tables also fall into the following categories: - Required: DSDT, FADT, GTDT, MADT, MCFG, RSDP, SPCR, XSDT - Recommended: BERT, EINJ, ERST, HEST, PCCT, SSDT - Optional: BGRT, CPEP, CSRT, DBG2, DRTM, ECDT, FACS, FPDT, IORT, MCHI, MPST, MSCT, NFIT, PMTT, RASF, SBST, SLIT, SPMI, SRAT, STAO, TCPA, TPM2, UEFI, XENV - Not supported: BOOT, DBGP, DMAR, ETDT, HPET, IBFT, IVRS, LPIT, MSDM, OEMx, PSDT, RSDT, SLIC, WAET, WDAT, WDRT, WPBT ====== ======================================================================== Table Usage for ARMv8 Linux ====== ======================================================================== BERT Section 18.3 (signature == "BERT") **Boot Error Record Table** Must be supplied if RAS support is provided by the platform. It is recommended this table be supplied. BOOT Signature Reserved (signature == "BOOT") **simple BOOT flag table** Microsoft only table, will not be supported. BGRT Section 5.2.22 (signature == "BGRT") **Boot Graphics Resource Table** Optional, not currently supported, with no real use-case for an ARM server. CPEP Section 5.2.18 (signature == "CPEP") **Corrected Platform Error Polling table** Optional, not currently supported, and not recommended until such time as ARM-compatible hardware is available, and the specification suitably modified. CSRT Signature Reserved (signature == "CSRT") **Core System Resources Table** Optional, not currently supported. DBG2 Signature Reserved (signature == "DBG2") **DeBuG port table 2** License has changed and should be usable. Optional if used instead of earlycon=<device> on the command line. DBGP Signature Reserved (signature == "DBGP") **DeBuG Port table** Microsoft only table, will not be supported. DSDT Section 5.2.11.1 (signature == "DSDT") **Differentiated System Description Table** A DSDT is required; see also SSDT. ACPI tables contain only one DSDT but can contain one or more SSDTs, which are optional. Each SSDT can only add to the ACPI namespace, but cannot modify or replace anything in the DSDT. DMAR Signature Reserved (signature == "DMAR") **DMA Remapping table** x86 only table, will not be supported. DRTM Signature Reserved (signature == "DRTM") **Dynamic Root of Trust for Measurement table** Optional, not currently supported. ECDT Section 5.2.16 (signature == "ECDT") **Embedded Controller Description Table** Optional, not currently supported, but could be used on ARM if and only if one uses the GPE_BIT field to represent an IRQ number, since there are no GPE blocks defined in hardware reduced mode. This would need to be modified in the ACPI specification. EINJ Section 18.6 (signature == "EINJ") **Error Injection table** This table is very useful for testing platform response to error conditions; it allows one to inject an error into the system as if it had actually occurred. However, this table should not be shipped with a production system; it should be dynamically loaded and executed with the ACPICA tools only during testing. ERST Section 18.5 (signature == "ERST") **Error Record Serialization Table** On a platform supports RAS, this table must be supplied if it is not UEFI-based; if it is UEFI-based, this table may be supplied. When this table is not present, UEFI run time service will be utilized to save and retrieve hardware error information to and from a persistent store. ETDT Signature Reserved (signature == "ETDT") **Event Timer Description Table** Obsolete table, will not be supported. FACS Section 5.2.10 (signature == "FACS") **Firmware ACPI Control Structure** It is unlikely that this table will be terribly useful. If it is provided, the Global Lock will NOT be used since it is not part of the hardware reduced profile, and only 64-bit address fields will be considered valid. FADT Section 5.2.9 (signature == "FACP") **Fixed ACPI Description Table** Required for arm64. The HW_REDUCED_ACPI flag must be set. All of the fields that are to be ignored when HW_REDUCED_ACPI is set are expected to be set to zero. If an FACS table is provided, the X_FIRMWARE_CTRL field is to be used, not FIRMWARE_CTRL. If PSCI is used (as is recommended), make sure that ARM_BOOT_ARCH is filled in properly - that the PSCI_COMPLIANT flag is set and that PSCI_USE_HVC is set or unset as needed (see table 5-37). For the DSDT that is also required, the X_DSDT field is to be used, not the DSDT field. FPDT Section 5.2.23 (signature == "FPDT") **Firmware Performance Data Table** Optional, not currently supported. GTDT Section 5.2.24 (signature == "GTDT") **Generic Timer Description Table** Required for arm64. HEST Section 18.3.2 (signature == "HEST") **Hardware Error Source Table** ARM-specific error sources have been defined; please use those or the PCI types such as type 6 (AER Root Port), 7 (AER Endpoint), or 8 (AER Bridge), or use type 9 (Generic Hardware Error Source). Firmware first error handling is possible if and only if Trusted Firmware is being used on arm64. Must be supplied if RAS support is provided by the platform. It is recommended this table be supplied. HPET Signature Reserved (signature == "HPET") **High Precision Event timer Table** x86 only table, will not be supported. IBFT Signature Reserved (signature == "IBFT") **iSCSI Boot Firmware Table** Microsoft defined table, support TBD. IORT Signature Reserved (signature == "IORT") **Input Output Remapping Table** arm64 only table, required in order to describe IO topology, SMMUs, and GIC ITSs, and how those various components are connected together, such as identifying which components are behind which SMMUs/ITSs. This table will only be required on certain SBSA platforms (e.g., when using GICv3-ITS and an SMMU); on SBSA Level 0 platforms, it remains optional. IVRS Signature Reserved (signature == "IVRS") **I/O Virtualization Reporting Structure** x86_64 (AMD) only table, will not be supported. LPIT Signature Reserved (signature == "LPIT") **Low Power Idle Table** x86 only table as of ACPI 5.1; starting with ACPI 6.0, processor descriptions and power states on ARM platforms should use the DSDT and define processor container devices (_HID ACPI0010, Section 8.4, and more specifically 8.4.3 and 8.4.4). MADT Section 5.2.12 (signature == "APIC") **Multiple APIC Description Table** Required for arm64. Only the GIC interrupt controller structures should be used (types 0xA - 0xF). MCFG Signature Reserved (signature == "MCFG") **Memory-mapped ConFiGuration space** If the platform supports PCI/PCIe, an MCFG table is required. MCHI Signature Reserved (signature == "MCHI") **Management Controller Host Interface table** Optional, not currently supported. MPST Section 5.2.21 (signature == "MPST") **Memory Power State Table** Optional, not currently supported. MSCT Section 5.2.19 (signature == "MSCT") **Maximum System Characteristic Table** Optional, not currently supported. MSDM Signature Reserved (signature == "MSDM") **Microsoft Data Management table** Microsoft only table, will not be supported. NFIT Section 5.2.25 (signature == "NFIT") **NVDIMM Firmware Interface Table** Optional, not currently supported. OEMx Signature of "OEMx" only **OEM Specific Tables** All tables starting with a signature of "OEM" are reserved for OEM use. Since these are not meant to be of general use but are limited to very specific end users, they are not recommended for use and are not supported by the kernel for arm64. PCCT Section 14.1 (signature == "PCCT) **Platform Communications Channel Table** Recommend for use on arm64; use of PCC is recommended when using CPPC to control performance and power for platform processors. PMTT Section 5.2.21.12 (signature == "PMTT") **Platform Memory Topology Table** Optional, not currently supported. PSDT Section 5.2.11.3 (signature == "PSDT") **Persistent System Description Table** Obsolete table, will not be supported. RASF Section 5.2.20 (signature == "RASF") **RAS Feature table** Optional, not currently supported. RSDP Section 5.2.5 (signature == "RSD PTR") **Root System Description PoinTeR** Required for arm64. RSDT Section 5.2.7 (signature == "RSDT") **Root System Description Table** Since this table can only provide 32-bit addresses, it is deprecated on arm64, and will not be used. If provided, it will be ignored. SBST Section 5.2.14 (signature == "SBST") **Smart Battery Subsystem Table** Optional, not currently supported. SLIC Signature Reserved (signature == "SLIC") **Software LIcensing table** Microsoft only table, will not be supported. SLIT Section 5.2.17 (signature == "SLIT") **System Locality distance Information Table** Optional in general, but required for NUMA systems. SPCR Signature Reserved (signature == "SPCR") **Serial Port Console Redirection table** Required for arm64. SPMI Signature Reserved (signature == "SPMI") **Server Platform Management Interface table** Optional, not currently supported. SRAT Section 5.2.16 (signature == "SRAT") **System Resource Affinity Table** Optional, but if used, only the GICC Affinity structures are read. To support arm64 NUMA, this table is required. SSDT Section 5.2.11.2 (signature == "SSDT") **Secondary System Description Table** These tables are a continuation of the DSDT; these are recommended for use with devices that can be added to a running system, but can also serve the purpose of dividing up device descriptions into more manageable pieces. An SSDT can only ADD to the ACPI namespace. It cannot modify or replace existing device descriptions already in the namespace. These tables are optional, however. ACPI tables should contain only one DSDT but can contain many SSDTs. STAO Signature Reserved (signature == "STAO") **_STA Override table** Optional, but only necessary in virtualized environments in order to hide devices from guest OSs. TCPA Signature Reserved (signature == "TCPA") **Trusted Computing Platform Alliance table** Optional, not currently supported, and may need changes to fully interoperate with arm64. TPM2 Signature Reserved (signature == "TPM2") **Trusted Platform Module 2 table** Optional, not currently supported, and may need changes to fully interoperate with arm64. UEFI Signature Reserved (signature == "UEFI") **UEFI ACPI data table** Optional, not currently supported. No known use case for arm64, at present. WAET Signature Reserved (signature == "WAET") **Windows ACPI Emulated devices Table** Microsoft only table, will not be supported. WDAT Signature Reserved (signature == "WDAT") **Watch Dog Action Table** Microsoft only table, will not be supported. WDRT Signature Reserved (signature == "WDRT") **Watch Dog Resource Table** Microsoft only table, will not be supported. WPBT Signature Reserved (signature == "WPBT") **Windows Platform Binary Table** Microsoft only table, will not be supported. XENV Signature Reserved (signature == "XENV") **Xen project table** Optional, used only by Xen at present. XSDT Section 5.2.8 (signature == "XSDT") **eXtended System Description Table** Required for arm64. ====== ======================================================================== ACPI Objects ------------ The expectations on individual ACPI objects that are likely to be used are shown in the list that follows; any object not explicitly mentioned below should be used as needed for a particular platform or particular subsystem, such as power management or PCI. ===== ================ ======================================================== Name Section Usage for ARMv8 Linux ===== ================ ======================================================== _CCA 6.2.17 This method must be defined for all bus masters on arm64 - there are no assumptions made about whether such devices are cache coherent or not. The _CCA value is inherited by all descendants of these devices so it does not need to be repeated. Without _CCA on arm64, the kernel does not know what to do about setting up DMA for the device. NB: this method provides default cache coherency attributes; the presence of an SMMU can be used to modify that, however. For example, a master could default to non-coherent, but be made coherent with the appropriate SMMU configuration (see Table 17 of the IORT specification, ARM Document DEN 0049B). _CID 6.1.2 Use as needed, see also _HID. _CLS 6.1.3 Use as needed, see also _HID. _CPC 8.4.7.1 Use as needed, power management specific. CPPC is recommended on arm64. _CRS 6.2.2 Required on arm64. _CSD 8.4.2.2 Use as needed, used only in conjunction with _CST. _CST 8.4.2.1 Low power idle states (8.4.4) are recommended instead of C-states. _DDN 6.1.4 This field can be used for a device name. However, it is meant for DOS device names (e.g., COM1), so be careful of its use across OSes. _DSD 6.2.5 To be used with caution. If this object is used, try to use it within the constraints already defined by the Device Properties UUID. Only in rare circumstances should it be necessary to create a new _DSD UUID. In either case, submit the _DSD definition along with any driver patches for discussion, especially when device properties are used. A driver will not be considered complete without a corresponding _DSD description. Once approved by kernel maintainers, the UUID or device properties must then be registered with the UEFI Forum; this may cause some iteration as more than one OS will be registering entries. _DSM 9.1.1 Do not use this method. It is not standardized, the return values are not well documented, and it is currently a frequent source of error. \_GL 5.7.1 This object is not to be used in hardware reduced mode, and therefore should not be used on arm64. _GLK 6.5.7 This object requires a global lock be defined; there is no global lock on arm64 since it runs in hardware reduced mode. Hence, do not use this object on arm64. \_GPE 5.3.1 This namespace is for x86 use only. Do not use it on arm64. _HID 6.1.5 This is the primary object to use in device probing, though _CID and _CLS may also be used. _INI 6.5.1 Not required, but can be useful in setting up devices when UEFI leaves them in a state that may not be what the driver expects before it starts probing. _LPI 8.4.4.3 Recommended for use with processor definitions (_HID ACPI0010) on arm64. See also _RDI. _MLS 6.1.7 Highly recommended for use in internationalization. _OFF 7.2.2 It is recommended to define this method for any device that can be turned on or off. _ON 7.2.3 It is recommended to define this method for any device that can be turned on or off. \_OS 5.7.3 This method will return "Linux" by default (this is the value of the macro ACPI_OS_NAME on Linux). The command line parameter acpi_os=<string> can be used to set it to some other value. _OSC 6.2.11 This method can be a global method in ACPI (i.e., \_SB._OSC), or it may be associated with a specific device (e.g., \_SB.DEV0._OSC), or both. When used as a global method, only capabilities published in the ACPI specification are allowed. When used as a device-specific method, the process described for using _DSD MUST be used to create an _OSC definition; out-of-process use of _OSC is not allowed. That is, submit the device-specific _OSC usage description as part of the kernel driver submission, get it approved by the kernel community, then register it with the UEFI Forum. \_OSI 5.7.2 Deprecated on ARM64. As far as ACPI firmware is concerned, _OSI is not to be used to determine what sort of system is being used or what functionality is provided. The _OSC method is to be used instead. _PDC 8.4.1 Deprecated, do not use on arm64. \_PIC 5.8.1 The method should not be used. On arm64, the only interrupt model available is GIC. \_PR 5.3.1 This namespace is for x86 use only on legacy systems. Do not use it on arm64. _PRT 6.2.13 Required as part of the definition of all PCI root devices. _PRx 7.3.8-11 Use as needed; power management specific. If _PR0 is defined, _PR3 must also be defined. _PSx 7.3.2-5 Use as needed; power management specific. If _PS0 is defined, _PS3 must also be defined. If clocks or regulators need adjusting to be consistent with power usage, change them in these methods. _RDI 8.4.4.4 Recommended for use with processor definitions (_HID ACPI0010) on arm64. This should only be used in conjunction with _LPI. \_REV 5.7.4 Always returns the latest version of ACPI supported. \_SB 5.3.1 Required on arm64; all devices must be defined in this namespace. _SLI 6.2.15 Use is recommended when SLIT table is in use. _STA 6.3.7, It is recommended to define this method for any device 7.2.4 that can be turned on or off. See also the STAO table that provides overrides to hide devices in virtualized environments. _SRS 6.2.16 Use as needed; see also _PRS. _STR 6.1.10 Recommended for conveying device names to end users; this is preferred over using _DDN. _SUB 6.1.9 Use as needed; _HID or _CID are preferred. _SUN 6.1.11 Use as needed, but recommended. _SWS 7.4.3 Use as needed; power management specific; this may require specification changes for use on arm64. _UID 6.1.12 Recommended for distinguishing devices of the same class; define it if at all possible. ===== ================ ======================================================== ACPI Event Model ---------------- Do not use GPE block devices; these are not supported in the hardware reduced profile used by arm64. Since there are no GPE blocks defined for use on ARM platforms, ACPI events must be signaled differently. There are two options: GPIO-signaled interrupts (Section 5.6.5), and interrupt-signaled events (Section 5.6.9). Interrupt-signaled events are a new feature in the ACPI 6.1 specification. Either - or both - can be used on a given platform, and which to use may be dependent of limitations in any given SoC. If possible, interrupt-signaled events are recommended. ACPI Processor Control ---------------------- Section 8 of the ACPI specification changed significantly in version 6.0. Processors should now be defined as Device objects with _HID ACPI0007; do not use the deprecated Processor statement in ASL. All multiprocessor systems should also define a hierarchy of processors, done with Processor Container Devices (see Section 8.4.3.1, _HID ACPI0010); do not use processor aggregator devices (Section 8.5) to describe processor topology. Section 8.4 of the specification describes the semantics of these object definitions and how they interrelate. Most importantly, the processor hierarchy defined also defines the low power idle states that are available to the platform, along with the rules for determining which processors can be turned on or off and the circumstances that control that. Without this information, the processors will run in whatever power state they were left in by UEFI. Note too, that the processor Device objects defined and the entries in the MADT for GICs are expected to be in synchronization. The _UID of the Device object must correspond to processor IDs used in the MADT. It is recommended that CPPC (8.4.5) be used as the primary model for processor performance control on arm64. C-states and P-states may become available at some point in the future, but most current design work appears to favor CPPC. Further, it is essential that the ARMv8 SoC provide a fully functional implementation of PSCI; this will be the only mechanism supported by ACPI to control CPU power state. Booting of secondary CPUs using the ACPI parking protocol is possible, but discouraged, since only PSCI is supported for ARM servers. ACPI System Address Map Interfaces ---------------------------------- In Section 15 of the ACPI specification, several methods are mentioned as possible mechanisms for conveying memory resource information to the kernel. For arm64, we will only support UEFI for booting with ACPI, hence the UEFI GetMemoryMap() boot service is the only mechanism that will be used. ACPI Platform Error Interfaces (APEI) ------------------------------------- The APEI tables supported are described above. APEI requires the equivalent of an SCI and an NMI on ARMv8. The SCI is used to notify the OSPM of errors that have occurred but can be corrected and the system can continue correct operation, even if possibly degraded. The NMI is used to indicate fatal errors that cannot be corrected, and require immediate attention. Since there is no direct equivalent of the x86 SCI or NMI, arm64 handles these slightly differently. The SCI is handled as a high priority interrupt; given that these are corrected (or correctable) errors being reported, this is sufficient. The NMI is emulated as the highest priority interrupt possible. This implies some caution must be used since there could be interrupts at higher privilege levels or even interrupts at the same priority as the emulated NMI. In Linux, this should not be the case but one should be aware it could happen. ACPI Objects Not Supported on ARM64 ----------------------------------- While this may change in the future, there are several classes of objects that can be defined, but are not currently of general interest to ARM servers. Some of these objects have x86 equivalents, and may actually make sense in ARM servers. However, there is either no hardware available at present, or there may not even be a non-ARM implementation yet. Hence, they are not currently supported. The following classes of objects are not supported: - Section 9.2: ambient light sensor devices - Section 9.3: battery devices - Section 9.4: lids (e.g., laptop lids) - Section 9.8.2: IDE controllers - Section 9.9: floppy controllers - Section 9.10: GPE block devices - Section 9.15: PC/AT RTC/CMOS devices - Section 9.16: user presence detection devices - Section 9.17: I/O APIC devices; all GICs must be enumerable via MADT - Section 9.18: time and alarm devices (see 9.15) - Section 10: power source and power meter devices - Section 11: thermal management - Section 12: embedded controllers interface - Section 13: SMBus interfaces This also means that there is no support for the following objects: ==== =========================== ==== ========== Name Section Name Section ==== =========================== ==== ========== _ALC 9.3.4 _FDM 9.10.3 _ALI 9.3.2 _FIX 6.2.7 _ALP 9.3.6 _GAI 10.4.5 _ALR 9.3.5 _GHL 10.4.7 _ALT 9.3.3 _GTM 9.9.2.1.1 _BCT 10.2.2.10 _LID 9.5.1 _BDN 6.5.3 _PAI 10.4.4 _BIF 10.2.2.1 _PCL 10.3.2 _BIX 10.2.2.1 _PIF 10.3.3 _BLT 9.2.3 _PMC 10.4.1 _BMA 10.2.2.4 _PMD 10.4.8 _BMC 10.2.2.12 _PMM 10.4.3 _BMD 10.2.2.11 _PRL 10.3.4 _BMS 10.2.2.5 _PSR 10.3.1 _BST 10.2.2.6 _PTP 10.4.2 _BTH 10.2.2.7 _SBS 10.1.3 _BTM 10.2.2.9 _SHL 10.4.6 _BTP 10.2.2.8 _STM 9.9.2.1.1 _DCK 6.5.2 _UPD 9.16.1 _EC 12.12 _UPP 9.16.2 _FDE 9.10.1 _WPC 10.5.2 _FDI 9.10.2 _WPP 10.5.3 ==== =========================== ==== ========== |