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Diffstat (limited to 'Documentation/arm64/acpi_object_usage.txt')
| -rw-r--r-- | Documentation/arm64/acpi_object_usage.txt | 343 |
1 files changed, 186 insertions, 157 deletions
diff --git a/Documentation/arm64/acpi_object_usage.txt b/Documentation/arm64/acpi_object_usage.txt index a6e1a1805e51..c77010c5c1f0 100644 --- a/Documentation/arm64/acpi_object_usage.txt +++ b/Documentation/arm64/acpi_object_usage.txt @@ -13,14 +13,14 @@ 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, SSDT + -- Recommended: BERT, EINJ, ERST, HEST, PCCT, SSDT - -- Optional: BGRT, CPEP, CSRT, DRTM, ECDT, FACS, FPDT, MCHI, MPST, - MSCT, RASF, SBST, SLIT, SPMI, SRAT, TCPA, TPM2, UEFI - - -- Not supported: BOOT, DBG2, DBGP, DMAR, ETDT, HPET, IBFT, IVRS, - LPIT, MSDM, RSDT, SLIC, WAET, WDAT, WDRT, WPBT + -- 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 ----- ---------------------------------------------------------------- @@ -50,7 +50,8 @@ CSRT Signature Reserved (signature == "CSRT") DBG2 Signature Reserved (signature == "DBG2") == DeBuG port table 2 == - Microsoft only table, will not be supported. + 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 == @@ -133,10 +134,11 @@ GTDT Section 5.2.24 (signature == "GTDT") HEST Section 18.3.2 (signature == "HEST") == Hardware Error Source Table == - Until further error source types are defined, use only types 6 (AER - Root Port), 7 (AER Endpoint), 8 (AER Bridge), or 9 (Generic Hardware - Error Source). Firmware first error handling is possible if and only - if Trusted Firmware is being used on arm64. + 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. @@ -149,20 +151,30 @@ 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; future versions have been adapted for - use with ARM and will be recommended in order to support ACPI power - management. + 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 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 - 0xE). + should be used (types 0xA - 0xF). MCFG Signature Reserved (signature == "MCFG") == Memory-mapped ConFiGuration space == @@ -176,14 +188,38 @@ 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. -MSCT Section 5.2.19 (signature == "MSCT") - == Maximum System Characteristic Table == +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. @@ -195,7 +231,7 @@ RSDP Section 5.2.5 (signature == "RSD PTR") 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. + on arm64, and will not be used. If provided, it will be ignored. SBST Section 5.2.14 (signature == "SBST") == Smart Battery Subsystem Table == @@ -220,7 +256,7 @@ SPMI Signature Reserved (signature == "SPMI") SRAT Section 5.2.16 (signature == "SRAT") == System Resource Affinity Table == Optional, but if used, only the GICC Affinity structures are read. - To support NUMA, this table is required. + To support arm64 NUMA, this table is required. SSDT Section 5.2.11.2 (signature == "SSDT") == Secondary System Description Table == @@ -235,6 +271,11 @@ SSDT Section 5.2.11.2 (signature == "SSDT") 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 @@ -266,6 +307,10 @@ 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. @@ -273,44 +318,46 @@ XSDT Section 5.2.8 (signature == "XSDT") ACPI Objects ------------ -The expectations on individual ACPI objects are discussed in the list that -follows: +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 ---- ------------ ------------------------------------------------- -_ADR 6.1.1 Use as needed. - -_BBN 6.5.5 Use as needed; PCI-specific. +_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. -_BDN 6.5.3 Optional; not likely to be used on arm64. + 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). -_CCA 6.2.17 This method should be defined for all bus masters - on arm64. While cache coherency is assumed, making - it explicit ensures the kernel will set up DMA as - it should. +_CID 6.1.2 Use as needed, see also _HID. -_CDM 6.2.1 Optional, to be used only for processor devices. +_CLS 6.1.3 Use as needed, see also _HID. -_CID 6.1.2 Use as needed. - -_CLS 6.1.3 Use as needed. +_CPC 8.4.7.1 Use as needed, power management specific. CPPC is + recommended on arm64. _CRS 6.2.2 Required on arm64. -_DCK 6.5.2 Optional; not likely to be used 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. -_DEP 6.5.8 Use as needed. - -_DIS 6.2.3 Optional, for power management use. - -_DLM 5.7.5 Optional. - -_DMA 6.2.4 Optional. - _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 @@ -325,20 +372,10 @@ _DSD 6.2.5 To be used with caution. If this object is used, try with the UEFI Forum; this may cause some iteration as more than one OS will be registering entries. -_DSM Do not use this method. It is not standardized, the +_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. -_DSW 7.2.1 Use as needed; power management specific. - -_EDL 6.3.1 Optional. - -_EJD 6.3.2 Optional. - -_EJx 6.3.3 Optional. - -_FIX 6.2.7 x86 specific, not used on arm64. - \_GL 5.7.1 This object is not to be used in hardware reduced mode, and therefore should not be used on arm64. @@ -349,35 +386,22 @@ _GLK 6.5.7 This object requires a global lock be defined; there \_GPE 5.3.1 This namespace is for x86 use only. Do not use it on arm64. -_GSB 6.2.7 Optional. - -_HID 6.1.5 Use as needed. This is the primary object to use in - device probing, though _CID and _CLS may also be used. - -_HPP 6.2.8 Optional, PCI specific. - -_HPX 6.2.9 Optional, PCI specific. - -_HRV 6.1.6 Optional, use as needed to clarify device behavior; in - some cases, this may be easier to use than _DSD. +_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. -_IRC 7.2.15 Use as needed; power management specific. - -_LCK 6.3.4 Optional. - -_MAT 6.2.10 Optional; see also the MADT. +_LPI 8.4.4.3 Recommended for use with processor definitions (_HID + ACPI0010) on arm64. See also _RDI. -_MLS 6.1.7 Optional, but highly recommended for use in - internationalization. +_MLS 6.1.7 Highly recommended for use in internationalization. -_OFF 7.1.2 It is recommended to define this method for any device +_OFF 7.2.2 It is recommended to define this method for any device that can be turned on or off. -_ON 7.1.3 It is recommended to define this method for any device +_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 @@ -398,122 +422,107 @@ _OSC 6.2.11 This method can be a global method in ACPI (i.e., by the kernel community, then register it with the UEFI Forum. -\_OSI 5.7.2 Deprecated on ARM64. Any invocation of this method - will print a warning on the console and return false. - That is, as far as ACPI firmware is concerned, _OSI - cannot be used to determine what sort of system is - being used or what functionality is provided. The - _OSC method is to be used instead. - -_OST 6.3.5 Optional. +\_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. -_PLD 6.1.8 Optional. - \_PR 5.3.1 This namespace is for x86 use only on legacy systems. Do not use it on arm64. -_PRS 6.2.12 Optional. - _PRT 6.2.13 Required as part of the definition of all PCI root devices. -_PRW 7.2.13 Use as needed; power management specific. - -_PRx 7.2.8-11 Use as needed; power management specific. If _PR0 is +_PRx 7.3.8-11 Use as needed; power management specific. If _PR0 is defined, _PR3 must also be defined. -_PSC 7.2.6 Use as needed; power management specific. - -_PSE 7.2.7 Use as needed; power management specific. - -_PSW 7.2.14 Use as needed; power management specific. - -_PSx 7.2.2-5 Use as needed; power management specific. If _PS0 is +_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. -\_PTS 7.3.1 Use as needed; power management specific. - -_PXM 6.2.14 Optional. - -_REG 6.5.4 Use as needed. +_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. -_RMV 6.3.6 Optional. - \_SB 5.3.1 Required on arm64; all devices must be defined in this namespace. -_SEG 6.5.6 Use as needed; PCI-specific. - -\_SI 5.3.1, Optional. - 9.1 - -_SLI 6.2.15 Optional; recommended when SLIT table is in use. +_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 - 7.1.4 that can be turned on or off. + 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 Optional; see also _PRS. +_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 Optional. - -\_Sx 7.3.2 Use as needed; power management specific. - -_SxD 7.2.16-19 Use as needed; power management specific. - -_SxW 7.2.20-24 Use as needed; power management specific. +_SUN 6.1.11 Use as needed, but recommended. -_SWS 7.3.3 Use as needed; power management specific; this may +_SWS 7.4.3 Use as needed; power management specific; this may require specification changes for use on arm64. -\_TTS 7.3.4 Use as needed; power management specific. - -\_TZ 5.3.1 Optional. - _UID 6.1.12 Recommended for distinguishing devices of the same class; define it if at all possible. -\_WAK 7.3.5 Use as needed; power management specific. + 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, GPIO-signaled interrupts should be used for creating system events. +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 is currently undergoing change that -should be completed in the 6.0 version of the specification. Processor -performance control will be handled differently for arm64 at that point -in time. Processor aggregator devices (section 8.5) will not be used, -for example, but another similar mechanism instead. - -While UEFI constrains what we can say until the release of 6.0, it is -recommended that CPPC (8.4.5) be used as the primary model. This will -still be useful into the future. C-states and P-states will still be -provided, but most of the current design work appears to favor CPPC. +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 (including secondary CPU booting). - -More details will be provided on the release of the ACPI 6.0 specification. +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 @@ -535,21 +544,25 @@ 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 normal GPIO-signaled -interrupt; given that these are corrected (or correctable) errors being -reported, this is sufficient. The NMI is emulated as the highest priority -GPIO-signaled 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. +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. -These are not supported: +The following classes of objects are not supported: -- Section 9.2: ambient light sensor devices @@ -571,16 +584,6 @@ These are not supported: -- Section 9.18: time and alarm devices (see 9.15) - -ACPI Objects Not Yet Implemented --------------------------------- -While these objects have x86 equivalents, and they do make some sense in ARM -servers, there is either no hardware available at present, or in some cases -there may not yet be a non-ARM implementation. Hence, they are currently not -implemented though that may change in the future. - -Not yet implemented are: - -- Section 10: power source and power meter devices -- Section 11: thermal management @@ -589,5 +592,31 @@ Not yet implemented are: -- Section 13: SMBus interfaces - -- Section 17: NUMA support (prototypes have been submitted for - review) + +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 + |