MdePkg/Library/BaseLib/Ia32/WriteCr4.c

   1 /** @file
   2   AsmWriteCr4 function
   3
   4   Copyright (c) 2006 - 2008, Intel Corporation. All rights reserved.<BR>
   5   SPDX-License-Identifier: BSD-2-Clause-Patent
   6
   7 **/
   8
   9 /**
  10   Writes a value to Control Register 4 (CR4).
  11
  12   Writes and returns a new value to CR4. This function is only available on
  13   IA-32 and x64. This writes a 32-bit value on IA-32 and a 64-bit value on x64.
  14
  15   @param  Value The value to write to CR4.
  16
  17   @return The value written to CR4.
  18
  19 **/
  20 UINTN
  21 EFIAPI
  22 AsmWriteCr4 (
  23   UINTN  Value
  24   )
  25 {
  26   _asm {
  27     mov     eax, Value
  28     _emit  0x0f  // mov  cr4, eax
  29     _emit  0x22
  30     _emit  0xE0
  31   }
  32 }