2 files changed, 8 insertions, 2 deletions
diff --git a/UefiCpuPkg/CpuDxe/Ia32/CpuAsm.asm b/UefiCpuPkg/CpuDxe/Ia32/CpuAsm.asm
index 68454bdeca..a279e6ab5a 100644
--- a/UefiCpuPkg/CpuDxe/Ia32/CpuAsm.asm
+++ b/UefiCpuPkg/CpuDxe/Ia32/CpuAsm.asm
@@ -1,7 +1,7 @@
       TITLE   CpuAsm.asm:
 ;------------------------------------------------------------------------------
 ;*
-;*   Copyright (c) 2006 - 2010, Intel Corporation. All rights reserved.<BR>
+;*   Copyright (c) 2006 - 2011, Intel Corporation. All rights reserved.<BR>
 ;*   This program and the accompanying materials
 ;*   are licensed and made available under the terms and conditions of the BSD License
 ;*   which accompanies this distribution.  The full text of the license may be found at
@@ -272,6 +272,9 @@ ErrorCodeAndVectorOnStack:
     mov     edi, esp
     db      0fh, 0aeh, 07h ;fxsave [edi]
 
+;; UEFI calling convention for IA32 requires that Direction flag in EFLAGs is clear
+    cld
+
 ;; UINT32  ExceptionData;
     push    dword ptr [ebp + 2 * 4]
 
diff --git a/UefiCpuPkg/CpuDxe/X64/CpuAsm.asm b/UefiCpuPkg/CpuDxe/X64/CpuAsm.asm
index 79edb7b83e..68fcd3f404 100644
--- a/UefiCpuPkg/CpuDxe/X64/CpuAsm.asm
+++ b/UefiCpuPkg/CpuDxe/X64/CpuAsm.asm
@@ -1,7 +1,7 @@
       TITLE   CpuAsm.asm: 
 ;------------------------------------------------------------------------------
 ;*
-;*   Copyright (c) 2008 - 2010, Intel Corporation. All rights reserved.<BR>
+;*   Copyright (c) 2008 - 2011, Intel Corporation. All rights reserved.<BR>
 ;*   This program and the accompanying materials                          
 ;*   are licensed and made available under the terms and conditions of the BSD License         
 ;*   which accompanies this distribution.  The full text of the license may be found at        
@@ -223,6 +223,9 @@ NoErrorCode:
     mov rdi, rsp
     db 0fh, 0aeh, 07h ;fxsave [rdi]
 
+;; UEFI calling convention for x64 requires that Direction flag in EFLAGs is clear
+    cld
+
 ;; UINT32  ExceptionData;
     push    qword ptr [rbp + 16]