Il 26/08/2014 03:03, Laszlo Ersek ha scritto: > > The only way you could reliably fish out tables, operation regions etc. > from the qemu payload would be to write a near-full ACPI interpreter. > The goal of the interface is the polar opposite, ie. to require the > firmware to know the least possible about ACPI table specifics.
Could OvmfPkg include its own minimal implementation of AcpiTableProtocol? You can check that InstallAcpiTable calls do not override QEMU-provided tables (which is currently the case), and abort if that happens. OvmfPkg does not need to expose AcpiSdtProtocol---which I'm not even sure who uses; AcpiTableProtocol is small(ish) and a lot of code could go away as far as OVMF is concerned if you drop support for three ACPI versions. If you do that, you can parse only the QEMU-provided RSD PTR and RSDT (to find out which tables QEMU provides and avoid overriding them). In the meanwhile, UEFI could work on a new v2 AcpiTableProtocol that has an InstallAcpiTableNoRelocate function. With it, the QEMU ACPI table linker can, again, parse the RSDT, pass each table to InstallAcpiTableNoRelocate, and then discard the QEMU-provided RSDT. > RSD PTR being referenced in the config table is not even part of the > UEFI spec (if I searched it right); it's described in the ACPI spec. The > UEFI spec only names the relevant GUIDs, but doesn't explain how to use > them. > > In any case, under the IBFT example you name, we have a conflict because > ACPI tables have two genuine, distinct sources. IBFT comes from the > firmware, while the rest would come from QEMU. > > (I don't know if IBFT could be provided by QEMU. The ACPI 5.1 spec > doesn't describe the table. Googling led me to a license acceptance > window at Microsoft's site, which I closed.) No, it couldn't. The iBFT information depends on where the system boots from. Basically it's how the firmware tells the OS "I booted you from here, that's where you can get any other files you need". Basically it lets you configure your network and iSCSI initiator before you have a DHCP client. ftp://ftp.software.ibm.com/systems/support/bladecenter/iscsi_boot_firmware_table_v1.03.pdf Paolo > In practice, IBFT seems less important than the tables that QEMU does > offer -- embedded in blobs -- eg. I forgot to mention VCPU hotplug. ------------------------------------------------------------------------------ Slashdot TV. Video for Nerds. Stuff that matters. http://tv.slashdot.org/ _______________________________________________ edk2-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/edk2-devel
