diff --git a/MdeModulePkg/Core/Dxe/DxeMain/DxeMain.c b/MdeModulePkg/Core/Dxe/DxeMain/DxeMain.c
index 2f72670c2a..2cf082b74f 100644
--- a/MdeModulePkg/Core/Dxe/DxeMain/DxeMain.c
+++ b/MdeModulePkg/Core/Dxe/DxeMain/DxeMain.c
@@ -244,7 +244,7 @@ DxeMain (
   //
   // Initialize Debug Agent to support source level debug in DXE phase
   //
-  InitializeDebugAgent (DEBUG_AGENT_INIT_DXE, HobStart);
+  InitializeDebugAgent (DEBUG_AGENT_INIT_DXE_CORE, HobStart);
 
   //
   // Initialize Memory Services
@@ -685,6 +685,11 @@ CoreExitBootServices (
   //
   CoreNotifySignalList (&gEfiEventExitBootServicesGuid);
 
+  //
+  // Disable interrupt of Debug timer.
+  //
+  SaveAndSetDebugTimerInterrupt (FALSE);
+
   //
   // Disable CPU Interrupts
   //
diff --git a/MdeModulePkg/Include/Library/DebugAgentLib.h b/MdeModulePkg/Include/Library/DebugAgentLib.h
index a5c311482d..2367139729 100644
--- a/MdeModulePkg/Include/Library/DebugAgentLib.h
+++ b/MdeModulePkg/Include/Library/DebugAgentLib.h
@@ -17,10 +17,11 @@
 
 #define DEBUG_AGENT_INIT_PREMEM_SEC      1
 #define DEBUG_AGENT_INIT_POSTMEM_SEC     2
-#define DEBUG_AGENT_INIT_DXE             3
+#define DEBUG_AGENT_INIT_DXE_CORE        3
 #define DEBUG_AGENT_INIT_SMM             4
 #define DEBUG_AGENT_INIT_ENTER_SMI       5
 #define DEBUG_AGENT_INIT_EXIT_SMI        6
+#define DEBUG_AGENT_INIT_S3              7
 
 /**
   Initialize debug agent.