On 01/31/14 18:21, Sergey Isakov wrote: > Hi, > EFI_ACPI_TABLE_PROTOCOL is to get ACPI tables while > ACPI_SDT_PROTOCOL is to analyze them. > Wishes, > Sergey > > > On 31 янв. 2014 г., at 18:29, Yao, Jiewen <jiewen....@intel.com > <mailto:jiewen....@intel.com>> wrote: > >> HI >> UEFI OS loader or OS kernel can get ACPI2.0 RSDP from UEFI >> configuration table via EFI_ACPI_20_TABLE_GUID. See UEFI2.4a spec, >> page 93. >> Then it can parse all ACPI information, like RSDP->XSDT->FADT->DSDT. >> >> I think you also use this way too. >> >> The limitation of ACPI_SDT_PROTOCOL is that: It is defined in PI spec, >> and not all platform BIOS produce it, as far as I know.
My current understanding is that both sets of statements are correct. (i) EFI_ACPI_TABLE_PROTOCOL is good for installing new tables, and for removing some tables that have been installed with the same protocol instance. UninstallAcpiTable() takes the same TableKey as input that InstallAcpiTable() returned earlier. When tables are un-/installed like this, they are un-/linked under the RSDP (as Jiewen says). (ii) The absolute root / anchor for this "tree of tables" is gST->ConfigurationTable. (See PublishTables() in "MdeModulePkg/Universal/Acpi/AcpiTableDxe/AcpiTableProtocol.c".) The entry with VendorGuid==gEfiAcpiTableGuid (or VendorGuid==gEfiAcpi10TableGuid) seems to point to the RSDP. According to the UEFI spec, after installing or uninstalling a table, with EFI_ACPI_TABLE_PROTOCOL, interested parties need to re-fetch this entry from gST->ConfigurationTable (ie. re-walk the entire chain). An example for locating the FACS, starting with gST->ConfigurationTable, is visible in FindAcpiFacsTable() [IntelFrameworkModulePkg/Universal/Acpi/AcpiS3SaveDxe/AcpiS3Save.c]. (iii) EFI_ACPI_SDT_PROTOCOL *seems* suitable for analyzing/modifying tables that contain AML and have been (or are being) installed with EFI_ACPI_TABLE_PROTOCOL. GetAcpiTable() allows one to find out about all such tables, and RegisterNotify() allows for an InstallAcpiTable() callback. As soon as the TableKey is available, OpenSdt() can be called to retrieve an EFI_ACPI_HANDLE, which allows further GetChild() / GetOption() / FindPath() calls. This looks awesome. I believe it's basically an AML parser. For example, in OVMF I guess we could derive "structured information" from QEMU's DSDT/SSDT (once I post the download patch), should we be forced to do that. This discussion is proving very beneficial (even if I'm incorrect in some spots). Thanks! Laszlo ------------------------------------------------------------------------------ WatchGuard Dimension instantly turns raw network data into actionable security intelligence. It gives you real-time visual feedback on key security issues and trends. Skip the complicated setup - simply import a virtual appliance and go from zero to informed in seconds. http://pubads.g.doubleclick.net/gampad/clk?id=123612991&iu=/4140/ostg.clktrk _______________________________________________ edk2-devel mailing list edk2-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/edk2-devel
