1 files changed, 77 insertions, 0 deletions
diff --git a/MdePkg/Library/UefiDebugLibConOut/DebugLibConstructor.c b/MdePkg/Library/UefiDebugLibConOut/DebugLibConstructor.c
new file mode 100644
index 0000000000..d4fdfbab55
--- /dev/null
+++ b/MdePkg/Library/UefiDebugLibConOut/DebugLibConstructor.c
@@ -0,0 +1,77 @@
+/** @file
+  UEFI Dxe DebugLib constructor that prevent some debug service after ExitBootServices event,
+  because some pointer is nulled at that phase.
+
+  Copyright (c) 2018, Microsoft Corporation
+  Copyright (c) 2015 - 2019, Intel Corporation. All rights reserved.<BR>
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+**/
+
+#include <Uefi.h>
+#include <Library/BaseLib.h>
+#include <Library/BaseMemoryLib.h>
+
+//
+// BOOLEAN value to indicate if it is at the post ExitBootServices pahse
+//
+BOOLEAN     mPostEBS = FALSE;
+
+EFI_EVENT   mExitBootServicesEvent;
+
+//
+// Pointer to SystemTable
+// This library instance may have a cycle consume with UefiBootServicesTableLib
+// because of the constructors.
+//
+EFI_SYSTEM_TABLE      *mDebugST;
+
+/**
+  This routine sets the mPostEBS for exit boot servies true
+  to prevent DebugPort protocol dereferences when the pointer is nulled.
+
+  @param  Event        Event whose notification function is being invoked.
+  @param  Context      Pointer to the notification function's context.
+
+**/
+VOID
+EFIAPI
+ExitBootServicesCallback (
+  EFI_EVENT   Event,
+  VOID*       Context
+  )
+{
+  mPostEBS = TRUE;
+  return;
+}
+
+/**
+  The constructor gets the pointers to the system table.
+  And create a event to indicate it is after ExitBootServices.
+
+  @param  ImageHandle     The firmware allocated handle for the EFI image.
+  @param  SystemTable     A pointer to the EFI System Table.
+
+  @retval EFI_SUCCESS     The constructor always returns EFI_SUCCESS.
+
+**/
+EFI_STATUS
+EFIAPI
+DxeDebugLibConstructor(
+  IN EFI_HANDLE                 ImageHandle,
+  IN EFI_SYSTEM_TABLE           *SystemTable
+  )
+{
+  mDebugST = SystemTable;
+
+  SystemTable->BootServices->CreateEventEx (
+                                EVT_NOTIFY_SIGNAL,
+                                TPL_NOTIFY,
+                                ExitBootServicesCallback,
+                                NULL,
+                                &gEfiEventExitBootServicesGuid,
+                                &mExitBootServicesEvent
+                                );
+
+  return EFI_SUCCESS;
+}