efiemu/i386/coredetect.c

   1 /*
   2  *  GRUB  --  GRand Unified Bootloader
   3  *  Copyright (C) 2009  Free Software Foundation, Inc.
   4  *
   5  *  GRUB is free software: you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License as published by
   7  *  the Free Software Foundation, either version 3 of the License, or
   8  *  (at your option) any later version.
   9  *
  10  *  GRUB is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19 #include <grub/efiemu/efiemu.h>
  20 #include <grub/machine/efiemu.h>
  21 #include <grub/command.h>
  22
  23 #define cpuid(num,a,b,c,d) \
  24   asm volatile ("xchgl %%ebx, %1; cpuid; xchgl %%ebx, %1" \
  25                 : "=a" (a), "=r" (b), "=c" (c), "=d" (d)  \
  26                 : "0" (num))
  27
  28 #define bit_LM (1 << 29)
  29
  30 char *
  31 grub_efiemu_get_default_core_name (void)
  32 {
  33
  34   unsigned int eax, ebx, ecx, edx;
  35   unsigned int max_level;
  36   unsigned int ext_level;
  37
  38   /* See if we can use cpuid.  */
  39   asm volatile ("pushfl; pushfl; popl %0; movl %0,%1; xorl %2,%0;"
  40                 "pushl %0; popfl; pushfl; popl %0; popfl"
  41                 : "=&r" (eax), "=&r" (ebx)
  42                 : "i" (0x00200000));
  43   if (((eax ^ ebx) & 0x00200000) == 0)
  44     return "efiemu32.o";
  45
  46   /* Check the highest input value for eax.  */
  47   cpuid (0, eax, ebx, ecx, edx);
  48   /* We only look at the first four characters.  */
  49   max_level = eax;
  50   if (max_level == 0)
  51     return "efiemu32.o";
  52
  53   cpuid (0x80000000, eax, ebx, ecx, edx);
  54   ext_level = eax;
  55   if (ext_level < 0x80000000)
  56     return "efiemu32.o";
  57
  58   cpuid (0x80000001, eax, ebx, ecx, edx);
  59   return (edx & bit_LM) ? "efiemu64.o" : "efiemu32.o";
  60 }