UefiCpuPkg/ResetVector/Vtf0/Ia32/Flat32ToFlat64.asm

   1 ;------------------------------------------------------------------------------
   2 ; @file
   3 ; Transition from 32 bit flat protected mode into 64 bit flat protected mode
   4 ;
   5 ; Copyright (c) 2008 - 2013, 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     OneTimeCall SetCr3ForPageTables64
  24
  25     mov     eax, cr4
  26     bts     eax, 5                      ; enable PAE
  27     mov     cr4, eax
  28
  29     mov     ecx, 0xc0000080
  30     rdmsr
  31     bts     eax, 8                      ; set LME
  32     wrmsr
  33
  34     mov     eax, cr0
  35     bts     eax, 31                     ; set PG
  36     mov     cr0, eax                    ; enable paging
  37
  38     jmp     LINEAR_CODE64_SEL:ADDR_OF(jumpTo64BitAndLandHere)
  39 BITS    64
  40 jumpTo64BitAndLandHere:
  41
  42     debugShowPostCode POSTCODE_64BIT_MODE
  43
  44     OneTimeCallRet Transition32FlatTo64Flat
  45