1 files changed, 46 insertions, 0 deletions
diff --git a/UefiCpuPkg/ResetVector/Vtf0/Ia32/32FlatTo64Flat.asm b/UefiCpuPkg/ResetVector/Vtf0/Ia32/32FlatTo64Flat.asm
new file mode 100644
index 000000000..a97f9cc70
--- /dev/null
+++ b/UefiCpuPkg/ResetVector/Vtf0/Ia32/32FlatTo64Flat.asm
@@ -0,0 +1,46 @@
+;------------------------------------------------------------------------------
+; @file
+; Transition from 32 bit flat protected mode into 64 bit flat protected mode
+;
+; Copyright (c) 2008 - 2009, Intel Corporation
+; All rights reserved. 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
+; http://opensource.org/licenses/bsd-license.php
+;
+; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+;
+;------------------------------------------------------------------------------
+
+BITS    32
+
+;
+; Modified:  EAX
+;
+Transition32FlatTo64Flat:
+
+    mov     eax, ((ADDR_OF_START_OF_RESET_CODE & ~0xfff) - 0x1000)
+    mov     cr3, eax
+
+    mov     eax, cr4
+    bts     eax, 5                      ; enable PAE
+    mov     cr4, eax                    
+
+    mov     ecx, 0xc0000080
+    rdmsr
+    bts     eax, 8                      ; set LME
+    wrmsr
+
+    mov     eax, cr0
+    bts     eax, 31                     ; set PG
+    mov     cr0, eax                    ; enable paging
+
+    jmp     LINEAR_CODE64_SEL:ADDR_OF(jumpTo64BitAndLandHere)
+BITS    64
+jumpTo64BitAndLandHere:
+
+    debugShowPostCode POSTCODE_64BIT_MODE
+
+    OneTimeCallRet Transition32FlatTo64Flat
+