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
This library provides an interface where variables can be saved and restored
using a file in a file system accessible to the firmware. It is expected
that a platform BDS library will use this library. The platform BDS
implementation can decide which devices to connect and then to attempt to use
for saving and restoring NV variables.
git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@9272 6f19259b-4bc3-4df7-8a09-765794883524
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