;------------------------------------------------------------------------------ ; ; Copyright (c) 2006, Intel Corporation. All rights reserved.<BR> ; SPDX-License-Identifier: BSD-2-Clause-Patent ; ; Module Name: ; ; ReadDr4.Asm ; ; Abstract: ; ; AsmReadDr4 function ; ; Notes: ; ;------------------------------------------------------------------------------ SECTION .text ;------------------------------------------------------------------------------ ; UINTN ; EFIAPI ; AsmReadDr4 ( ; VOID ; ); ;------------------------------------------------------------------------------ global ASM_PFX(AsmReadDr4) ASM_PFX(AsmReadDr4): ; ; DR4 is alias to DR6 only if DE (in CR4) is cleared. Otherwise, reading ; this register will cause a #UD exception. ; ; MS assembler doesn't support this instruction since no one would use it ; under normal circustances. Here opcode is used. ; DB 0xf, 0x21, 0xe0 ret