mirror of https://github.com/acidanthera/audk.git
05db0948cc
The presence of this GUID in the PPI database, and/or in the DXE protocol database (as dictated by the platform's needs in these firmware phases) implies that the platform provides the operating system with an ACPI-based hardware description. This is not necessarily exclusive with other types of hardware description (for example, a Device Tree-based one). A platform PEIM and/or DXE driver is supposed to produce a single instance of the PPI and/or protocol (with NULL contents), if appropriate. The decision to produce the PPI and/or protocol is platform specific; for example, in the DXE phase, it could depend on an HII checkbox / underlying non-volatile UEFI variable. In the DXE phase, the protocol is meant to be depended-upon by "MdeModulePkg/Universal/Acpi/AcpiTableDxe", indirectly: * In the long term, interested platforms will establish this dependency by hooking an (upcoming) NULL-class DepexLib instance into AcpiTableDxe in their DSC files, pointing DepexLib's DEPEX through a FixedAtBuild PCD to the GUID introduced here. (For the prerequisite BaseTools feature, refer to <https://bugzilla.tianocore.org/show_bug.cgi?id=443>). * In the short term, an interested platform may hook a private NULL-class library instance (called e.g. "PlatformHasAcpiLib") into AcpiTableDxe. Such a library instance would be a specialization of the above described generic DepexLib, with the DEPEX open-coded on the GUID introduced here. Either way, the platform makes EFI_ACPI_TABLE_PROTOCOL and (if enabled) EFI_ACPI_SDT_PROTOCOL dependent on the platform's dynamic decision to produce or not to produce a NULL protocol instance with this GUID. In turn, other (platform and universal) DXE drivers that produce ACPI tables will wait for EFI_ACPI_TABLE_PROTOCOL / EFI_ACPI_SDT_PROTOCOL, via DEPEX, protocol notify, or a simple gBS->LocateProtocol() in a "late enough" callback (such as Ready To Boot). Because this GUID is not standard, it is prefixed with EDKII / Edkii, as seen elsewhere in MdeModulePkg and SecurityPkg. In addition, an effort is made to avoid the phrase "AcpiPlatform", as that belongs to drivers / libraries that produce platform specific ACPI content (as opposed to deciding whether the entire firmware will have access to EFI_ACPI_TABLE_PROTOCOL, or any similar facilities in the PEI phase). Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Leif Lindholm <leif.lindholm@linaro.org> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> |
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| .. | ||
| Guid | ||
| Library | ||
| Protocol | ||
| fdt.h | ||
| libfdt.h | ||
| libfdt_env.h | ||