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  *
   6  *   This file is part of the Linux kernel, and is made available under
   7  *   the terms of the GNU General Public License version 2.
   8  *
   9  * ----------------------------------------------------------------------- */
  10
  11 /*
  12  * arch/i386/boot/mca.c
  13  *
  14  * Get the MCA system description table
  15  */
  16
  17 #include "boot.h"
  18
  19 int query_mca(void)
  20 {
  21         u8 err;
  22         u16 es, bx, len;
  23
  24         asm("pushw %%es ; "
  25             "int $0x15 ; "
  26             "setc %0 ; "
  27             "movw %%es, %1 ; "
  28             "popw %%es"
  29             : "=acd" (err), "=acdSD" (es), "=b" (bx)
  30             : "a" (0xc000));
  31
  32         if (err)
  33                 return -1;      /* No MCA present */
  34
  35         set_fs(es);
  36         len = rdfs16(bx);
  37
  38         if (len > sizeof(boot_params.sys_desc_table))
  39                 len = sizeof(boot_params.sys_desc_table);
  40
  41         copy_from_fs(&boot_params.sys_desc_table, bx, len);
  42         return 0;
  43 }