diff --git a/UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf b/UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf
index 03a8994..972c9ad 100644
--- a/UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf
+++ b/UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf
@@ -58,6 +58,7 @@
 
 [Guids]
   gEfiEventExitBootServicesGuid                 ## CONSUMES  ## Event
+  gEfiEventLegacyBootGuid                       ## CONSUMES  ## Event
 
 [Pcd]
   gUefiCpuPkgTokenSpaceGuid.PcdCpuMaxLogicalProcessorNumber        ## CONSUMES
diff --git a/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c b/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c
index 8be0bb8..7f3900b 100644
--- a/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c
+++ b/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c
@@ -22,6 +22,7 @@
 CPU_MP_DATA      *mCpuMpData = NULL;
 EFI_EVENT        mCheckAllApsEvent = NULL;
 EFI_EVENT        mMpInitExitBootServicesEvent = NULL;
+EFI_EVENT        mLegacyBootEvent = NULL;
 volatile BOOLEAN mStopCheckAllApsStatus = TRUE;
 VOID             *mReservedApLoopFunc = NULL;
 
@@ -340,6 +341,7 @@
                   AP_CHECK_INTERVAL
                   );
   ASSERT_EFI_ERROR (Status);
+
   Status = gBS->CreateEvent (
                   EVT_SIGNAL_EXIT_BOOT_SERVICES,
                   TPL_CALLBACK,
@@ -348,6 +350,16 @@
                   &mMpInitExitBootServicesEvent
                   );
   ASSERT_EFI_ERROR (Status);
+
+  Status = gBS->CreateEventEx (
+                  EVT_NOTIFY_SIGNAL,
+                  TPL_CALLBACK,
+                  MpInitChangeApLoopCallback,
+                  NULL,
+                  &gEfiEventLegacyBootGuid,
+                  &mLegacyBootEvent
+                  );
+  ASSERT_EFI_ERROR (Status);
 }
 
 /**