4 files changed, 80 insertions, 1 deletions
diff --git a/OvmfPkg/Include/Library/NvVarsFileLib.h b/OvmfPkg/Include/Library/NvVarsFileLib.h
index 63b1642f54..1a14b3fe9c 100644
--- a/OvmfPkg/Include/Library/NvVarsFileLib.h
+++ b/OvmfPkg/Include/Library/NvVarsFileLib.h
@@ -31,5 +31,21 @@ ConnectNvVarsToFileSystem (
   IN EFI_HANDLE    FsHandle
   );
 
+
+/**
+  Update non-volatile variables stored on the file system.
+
+  @return     The EFI_STATUS while attempting to update the variable on
+              the connected file system.
+  @retval     EFI_SUCCESS - The non-volatile variables were saved to the disk
+  @retval     EFI_NOT_STARTED - A file system has not been connected
+
+**/
+EFI_STATUS
+EFIAPI
+UpdateNvVarsOnFileSystem (
+  );
+
+
 #endif
 
diff --git a/OvmfPkg/Library/NvVarsFileLib/NvVarsFileLib.c b/OvmfPkg/Library/NvVarsFileLib/NvVarsFileLib.c
index 94e00e0bdb..62fee6f031 100644
--- a/OvmfPkg/Library/NvVarsFileLib/NvVarsFileLib.c
+++ b/OvmfPkg/Library/NvVarsFileLib/NvVarsFileLib.c
@@ -16,6 +16,8 @@
 #include <Library/DebugLib.h>
 #include <Library/NvVarsFileLib.h>
 
+EFI_HANDLE    mNvVarsFileLibFsHandle = NULL;
+
 
 /**
   Attempts to connect the NvVarsFileLib to the specified file system.
@@ -46,8 +48,36 @@ ConnectNvVarsToFileSystem (
   // to have connected successfully.
   //
   Status = SaveNvVarsToFs (FsHandle);
+  if (!EFI_ERROR (Status)) {
+    mNvVarsFileLibFsHandle = FsHandle;
+  }
 
   return Status;
 }
 
 
+/**
+  Update non-volatile variables stored on the file system.
+
+  @return     The EFI_STATUS while attempting to update the variable on
+              the connected file system.
+  @retval     EFI_SUCCESS - The non-volatile variables were saved to the disk
+  @retval     EFI_NOT_STARTED - A file system has not been connected
+
+**/
+EFI_STATUS
+EFIAPI
+UpdateNvVarsOnFileSystem (
+  )
+{
+  if (mNvVarsFileLibFsHandle == NULL) {
+    //
+    // A file system had not been connected to the library.
+    //
+    return EFI_NOT_STARTED;
+  } else {
+    return SaveNvVarsToFs (mNvVarsFileLibFsHandle);
+  }
+}
+
+
diff --git a/OvmfPkg/Library/PlatformBdsLib/BdsPlatform.c b/OvmfPkg/Library/PlatformBdsLib/BdsPlatform.c
index e4d1d4acbd..f3781b4b55 100644
--- a/OvmfPkg/Library/PlatformBdsLib/BdsPlatform.c
+++ b/OvmfPkg/Library/PlatformBdsLib/BdsPlatform.c
@@ -21,6 +21,8 @@
 
 VOID          *mEfiDevPathNotifyReg;
 EFI_EVENT     mEfiDevPathEvent;
+VOID          *mEmuVariableEventReg;
+EFI_EVENT     mEmuVariableEvent;
 BOOLEAN       mDetectVgaOnly;
 
 
@@ -815,6 +817,26 @@ ConnectRecursivelyIfPciMassStorage (
 }
 
 
+/**
+  This notification function is invoked when the
+  EMU Variable FVB has been changed.
+
+  @param  Event                 The event that occured
+  @param  Context               For EFI compatiblity.  Not used.
+
+**/
+VOID
+EFIAPI
+EmuVariablesUpdatedCallback (
+  IN  EFI_EVENT Event,
+  IN  VOID      *Context
+  )
+{
+  DEBUG ((EFI_D_INFO, "EmuVariablesUpdatedCallback\n"));
+  UpdateNvVarsOnFileSystem ();
+}
+
+
 EFI_STATUS
 EFIAPI
 VisitingFileSystemInstance (
@@ -836,6 +858,16 @@ VisitingFileSystemInstance (
   }
 
   ConnectedToFileSystem = TRUE;
+  mEmuVariableEvent =
+    EfiCreateProtocolNotifyEvent (
+      &gEfiDevicePathProtocolGuid,
+      TPL_CALLBACK,
+      EmuVariablesUpdatedCallback,
+      NULL,
+      &mEmuVariableEventReg
+      );
+  PcdSet64 (PcdEmuVariableEvent, (UINT64)(UINTN) mEmuVariableEvent);
+
   return EFI_SUCCESS;
 }
 
diff --git a/OvmfPkg/Library/PlatformBdsLib/PlatformBdsLib.inf b/OvmfPkg/Library/PlatformBdsLib/PlatformBdsLib.inf
index f8b64473bd..7d856f3177 100644
--- a/OvmfPkg/Library/PlatformBdsLib/PlatformBdsLib.inf
+++ b/OvmfPkg/Library/PlatformBdsLib/PlatformBdsLib.inf
@@ -50,9 +50,10 @@
   PciLib
   NvVarsFileLib
 
-[Pcd.common]
+[Pcd]
   gEfiIntelFrameworkModulePkgTokenSpaceGuid.PcdPlatformBootTimeOut
   gEfiIntelFrameworkModulePkgTokenSpaceGuid.PcdLogoFile
+  gUefiOvmfPkgTokenSpaceGuid.PcdEmuVariableEvent
 
 [Pcd.IA32, Pcd.X64]
   gEfiMdePkgTokenSpaceGuid.PcdFSBClock