Note:
* This only works before ExitBootServices
* For OVMF, variables are only preserved on the disk if there
is a hard disk connected which has a writeable FAT file system.
The Ovmf/Library/EmuVariableFvbLib library will look for the
gUefiOvmfPkgTokenSpaceGuid.PcdEmuVariableEvent PCD to be set to
a non-zero value. If set, it is treated as an event handle, and
each write to the EmuVariableFvb will cause the event to be
signaled.
In this change, the OVMF platform BDS library sets up this event,
and sets the PCD so that after each write to the EMU Variable FVB,
the non-volatile variables will be saved out to the file system.
The end result is that NV variables that are written prior to the
ExitBootServices call should be preserved by storing them on the
disk.
git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@9318 6f19259b-4bc3-4df7-8a09-765794883524
QEMU will automatically fill the video BIOS image into memory at the
legacy video BIOS memory location (0xc0000). This code will look
there for a EFI option rom image, and load it if it found. This
allows the video option ROM to be separated out from the main system
firmware image.
QEMU does not appear to emulate the PCI rom expansion method
for making the video BIOS available to the system.
git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@8942 6f19259b-4bc3-4df7-8a09-765794883524
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