On 1 December 2017 at 10:52, Laszlo Ersek <ler...@redhat.com> wrote: > On 12/01/17 09:51, Ard Biesheuvel wrote: >> On 30 November 2017 at 16:30, Laszlo Ersek <ler...@redhat.com> wrote: >>> (All of the below is only relevant for SMM_REQUIRE=FALSE.) >>> >>> For the emulated variable store, PlatformPei allocates reserved memory (as >>> early as possible, so that the address remains the same during reboot), >>> and PcdEmuVariableNvStoreReserved carries the address to >>> EmuVariableFvbRuntimeDxe. >>> >>> In addition, QemuFlashFvbServicesRuntimeDxe is always launched before >>> EmuVariableFvbRuntimeDxe, so that if flash variables are available, >>> QemuFlashFvbServicesRuntimeDxe can set PcdFlashNvStorageVariableBase64 >>> first, and EmuVariableFvbRuntimeDxe can exit early. This ordering is >>> currently enforced by adding QemuFlashFvbServicesRuntimeDxe to the APRIORI >>> DXE file. >>> >>> All of this is unnecessary when MEM_VARSTORE_EMU_ENABLE is set to FALSE. >>> In such a build, >>> >>> - (almost) remove the dynamic default for PcdEmuVariableNvStoreReserved >>> (we can't really do this because the PcdSet64() in >>> ReserveEmuVariableNvStore() wouldn't compile), >>> >> >> If that is the only concern, and the value is irrelevant, you could >> make it a patchable PCD instead > > This sounds interesting; I've never used patchable PCDs. Can you please > elaborate? > > Do you mean that for (SMM_REQUIRE==TRUE || > MEM_VARSTORE_EMU_ENABLE==FALSE), the DSC file should list > PcdEmuVariableNvStoreReserved somewhere else? >
Yes. > Does PcdSet work on patchable PCDs? > Yes. It's a bit icky because the value does not actually propagate to other modules, but that doesn't matter in this case. _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
