arch/x86/boot/mca.c

   1 /* -*- linux-c -*- ------------------------------------------------------- *
   2  *
   3  *   Copyright (C) 1991, 1992 Linus Torvalds
   4  *   Copyright 2007 rPath, Inc. - All Rights Reserved
   5  *   Copyright 2009 Intel Corporation; author H. Peter Anvin
   6  *
   7  *   This file is part of the Linux kernel, and is made available under
   8  *   the terms of the GNU General Public License version 2.
   9  *
  10  * ----------------------------------------------------------------------- */
  11
  12 /*
  13  * Get the MCA system description table
  14  */
  15
  16 #include "boot.h"
  17
  18 int query_mca(void)
  19 {
  20         struct biosregs ireg, oreg;
  21         u16 len;
  22
  23         initregs(&ireg);
  24         ireg.ah = 0xc0;
  25         intcall(0x15, &ireg, &oreg);
  26
  27         if (oreg.eflags & X86_EFLAGS_CF)
  28                 return -1;      /* No MCA present */
  29
  30         set_fs(oreg.es);
  31         len = rdfs16(oreg.bx);
  32
  33         if (len > sizeof(boot_params.sys_desc_table))
  34                 len = sizeof(boot_params.sys_desc_table);
  35
  36         copy_from_fs(&boot_params.sys_desc_table, oreg.bx, len);
  37         return 0;
  38 }