UefiCpuPkg/ResetVector/Vtf0/Ia32/32FlatTo64Flat.asm

   1 ;------------------------------------------------------------------------------
   2 ; @file
   3 ; Transition from 32 bit flat protected mode into 64 bit flat protected mode
   4 ;
   5 ; Copyright (c) 2008 - 2009, Intel Corporation. All rights reserved.<BR>
   6 ; This program and the accompanying materials
   7 ; are licensed and made available under the terms and conditions of the BSD License
   8 ; which accompanies this distribution.  The full text of the license may be found at
   9 ; http://opensource.org/licenses/bsd-license.php
  10 ;
  11 ; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  12 ; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  13 ;
  14 ;------------------------------------------------------------------------------
  15
  16 BITS    32
  17
  18 ;
  19 ; Modified:  EAX
  20 ;
  21 Transition32FlatTo64Flat:
  22
  23     mov     eax, ((ADDR_OF_START_OF_RESET_CODE & ~0xfff) - 0x1000)
  24     mov     cr3, eax
  25
  26     mov     eax, cr4
  27     bts     eax, 5                      ; enable PAE
  28     mov     cr4, eax
  29
  30     mov     ecx, 0xc0000080
  31     rdmsr
  32     bts     eax, 8                      ; set LME
  33     wrmsr
  34
  35     mov     eax, cr0
  36     bts     eax, 31                     ; set PG
  37     mov     cr0, eax                    ; enable paging
  38
  39     jmp     LINEAR_CODE64_SEL:ADDR_OF(jumpTo64BitAndLandHere)
  40 BITS    64
  41 jumpTo64BitAndLandHere:
  42
  43     debugShowPostCode POSTCODE_64BIT_MODE
  44
  45     OneTimeCallRet Transition32FlatTo64Flat
  46