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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-06 01:02:30 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-06 01:02:30 +0000 |
commit | 76cb841cb886eef6b3bee341a2266c76578724ad (patch) | |
tree | f5892e5ba6cc11949952a6ce4ecbe6d516d6ce58 /Documentation/arm64/acpi_object_usage.txt | |
parent | Initial commit. (diff) | |
download | linux-76cb841cb886eef6b3bee341a2266c76578724ad.tar.xz linux-76cb841cb886eef6b3bee341a2266c76578724ad.zip |
Adding upstream version 4.19.249.upstream/4.19.249upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'Documentation/arm64/acpi_object_usage.txt')
-rw-r--r-- | Documentation/arm64/acpi_object_usage.txt | 622 |
1 files changed, 622 insertions, 0 deletions
diff --git a/Documentation/arm64/acpi_object_usage.txt b/Documentation/arm64/acpi_object_usage.txt new file mode 100644 index 000000000..c77010c5c --- /dev/null +++ b/Documentation/arm64/acpi_object_usage.txt @@ -0,0 +1,622 @@ +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 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 + |