arch/all-pc/boot/grub2-aros/grub-core/commands/i386/cpuid.c

   1 /* cpuid.c - test for CPU features */
   2 /*
   3  *  GRUB  --  GRand Unified Bootloader
   4  *  Copyright (C) 2006, 2007, 2009  Free Software Foundation, Inc.
   5  *  Based on gcc/gcc/config/i386/driver-i386.c
   6  *
   7  *  GRUB is free software: you can redistribute it and/or modify
   8  *  it under the terms of the GNU General Public License as published by
   9  *  the Free Software Foundation, either version 3 of the License, or
  10  *  (at your option) any later version.
  11  *
  12  *  GRUB is distributed in the hope that it will be useful,
  13  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  *  GNU General Public License for more details.
  16  *
  17  *  You should have received a copy of the GNU General Public License
  18  *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
  19  */
  20
  21 #include <grub/dl.h>
  22 #include <grub/misc.h>
  23 #include <grub/mm.h>
  24 #include <grub/env.h>
  25 #include <grub/command.h>
  26 #include <grub/extcmd.h>
  27 #include <grub/i386/cpuid.h>
  28 #include <grub/i18n.h>
  29
  30 GRUB_MOD_LICENSE ("GPLv3+");
  31
  32 #define cpuid(num,a,b,c,d) \
  33   asm volatile ("xchgl %%ebx, %1; cpuid; xchgl %%ebx, %1" \
  34                 : "=a" (a), "=r" (b), "=c" (c), "=d" (d)  \
  35                 : "0" (num))
  36
  37 static const struct grub_arg_option options[] =
  38   {
  39     /* TRANSLATORS: "(default)" at the end means that this option is used if
  40        no argument is specified.  */
  41     {"long-mode", 'l', 0, N_("Check if CPU supports 64-bit (long) mode (default)."), 0, 0},
  42     {0, 0, 0, 0, 0, 0}
  43   };
  44
  45 #define bit_LM (1 << 29)
  46
  47 unsigned char grub_cpuid_has_longmode = 0;
  48
  49 static grub_err_t
  50 grub_cmd_cpuid (grub_extcmd_context_t ctxt __attribute__ ((unused)),
  51                 int argc __attribute__ ((unused)),
  52                 char **args __attribute__ ((unused)))
  53 {
  54   return grub_cpuid_has_longmode ? GRUB_ERR_NONE
  55     /* TRANSLATORS: it's a standalone boolean value,
  56        opposite of "true".  */
  57     : grub_error (GRUB_ERR_TEST_FAILURE, N_("false"));
  58 }
  59
  60 static grub_extcmd_t cmd;
  61
  62 GRUB_MOD_INIT(cpuid)
  63 {
  64 #ifdef __x86_64__
  65   /* grub-emu */
  66   grub_cpuid_has_longmode = 1;
  67 #else
  68   unsigned int eax, ebx, ecx, edx;
  69   unsigned int max_level;
  70   unsigned int ext_level;
  71
  72   /* See if we can use cpuid.  */
  73   asm volatile ("pushfl; pushfl; popl %0; movl %0,%1; xorl %2,%0;"
  74                 "pushl %0; popfl; pushfl; popl %0; popfl"
  75                 : "=&r" (eax), "=&r" (ebx)
  76                 : "i" (0x00200000));
  77   if (((eax ^ ebx) & 0x00200000) == 0)
  78     goto done;
  79
  80   /* Check the highest input value for eax.  */
  81   cpuid (0, eax, ebx, ecx, edx);
  82   /* We only look at the first four characters.  */
  83   max_level = eax;
  84   if (max_level == 0)
  85     goto done;
  86
  87   cpuid (0x80000000, eax, ebx, ecx, edx);
  88   ext_level = eax;
  89   if (ext_level < 0x80000000)
  90     goto done;
  91
  92   cpuid (0x80000001, eax, ebx, ecx, edx);
  93   grub_cpuid_has_longmode = !!(edx & bit_LM);
  94 done:
  95 #endif
  96
  97   cmd = grub_register_extcmd ("cpuid", grub_cmd_cpuid, 0,
  98                               "[-l]", N_("Check for CPU features."), options);
  99 }
 100
 101 GRUB_MOD_FINI(cpuid)
 102 {
 103   grub_unregister_extcmd (cmd);
 104 }