OvmfPkg/ResetVector/Ia32/32FlatTo64Flat.asm

   1 ;------------------------------------------------------------------------------
   2 ;
   3 ; Copyright (c) 2008, Intel Corporation
   4 ; All rights reserved. This program and the accompanying materials
   5 ; are licensed and made available under the terms and conditions of the BSD License
   6 ; which accompanies this distribution.  The full text of the license may be found at
   7 ; http://opensource.org/licenses/bsd-license.php
   8 ;
   9 ; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  10 ; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  11 ;
  12 ; Module Name:
  13 ;
  14 ;   32FlatTo64Flat.asm
  15 ;
  16 ; Abstract:
  17 ;
  18 ;   Transition from 32 bit flat protected mode into 64 bit flat protected mode
  19 ;
  20 ;------------------------------------------------------------------------------
  21
  22 BITS    32
  23
  24 Transition32FlatTo64Flat:
  25
  26     mov     eax, ((ADDR_OF_START_OF_RESET_CODE & ~0xfff) - 0x1000)
  27     mov     cr3, eax
  28
  29     mov     eax, cr4
  30     bts     eax, 5                      ; enable PAE
  31     mov     cr4, eax
  32
  33     mov     ecx, 0xc0000080
  34     rdmsr
  35     bts     eax, 8                      ; set LME
  36     wrmsr
  37
  38     mov     eax, cr0
  39     bts     eax, 31                     ; set PG
  40     mov     cr0, eax                    ; enable paging
  41
  42     jmp     LINEAR_CODE64_SEL:ADDR_OF(jumpTo64BitAndLandHere)
  43 BITS    64
  44 jumpTo64BitAndLandHere:
  45
  46     writeToSerialPort '6'
  47     writeToSerialPort '4'
  48     writeToSerialPort ' '
  49
  50     OneTimeCallRet Transition32FlatTo64Flat
  51