OVMF utilizes EmuVariableFvbRuntimeDxe to provide an emulated variable firmware volume block device for non-volatile variables. This allows the VariableRuntimeDxe and FaultTolerantWriteDxe to function without a real non-volatile backing store. git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@9317 6f19259b-4bc3-4df7-8a09-765794883524