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- /* cpuid.c - test for CPU features */
- /*
- * GRUB -- GRand Unified Bootloader
- * Copyright (C) 2006, 2007, 2009 Free Software Foundation, Inc.
- * Based on gcc/gcc/config/i386/driver-i386.c
- *
- * GRUB is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * GRUB is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with GRUB. If not, see <http://www.gnu.org/licenses/>.
- */
- #include <grub/dl.h>
- #include <grub/misc.h>
- #include <grub/mm.h>
- #include <grub/env.h>
- #include <grub/command.h>
- #include <grub/extcmd.h>
- #include <grub/i386/cpuid.h>
- #include <grub/i18n.h>
- GRUB_EXPORT(grub_cpuid_has_longmode);
- #define cpuid(num,a,b,c,d) \
- asm volatile ("xchgl %%ebx, %1; cpuid; xchgl %%ebx, %1" \
- : "=a" (a), "=r" (b), "=c" (c), "=d" (d) \
- : "0" (num))
- static const struct grub_arg_option options[] =
- {
- {"long-mode", 'l', 0, N_("Check for long mode flag (default)."), 0, 0},
- {0, 0, 0, 0, 0, 0}
- };
- #define bit_LM (1 << 29)
- unsigned char grub_cpuid_has_longmode = 0;
- static grub_err_t
- grub_cmd_cpuid (grub_extcmd_t cmd __attribute__ ((unused)),
- int argc __attribute__ ((unused)),
- char **args __attribute__ ((unused)))
- {
- return grub_cpuid_has_longmode ? GRUB_ERR_NONE
- : grub_error (GRUB_ERR_TEST_FAILURE, "false");
- }
- static grub_extcmd_t cmd;
- GRUB_MOD_INIT(cpuid)
- {
- #ifdef __x86_64__
- /* grub-emu */
- grub_cpuid_has_longmode = 1;
- #else
- unsigned int eax, ebx, ecx, edx;
- unsigned int max_level;
- unsigned int ext_level;
- /* See if we can use cpuid. */
- asm volatile ("pushfl; pushfl; popl %0; movl %0,%1; xorl %2,%0;"
- "pushl %0; popfl; pushfl; popl %0; popfl"
- : "=&r" (eax), "=&r" (ebx)
- : "i" (0x00200000));
- if (((eax ^ ebx) & 0x00200000) == 0)
- goto done;
- /* Check the highest input value for eax. */
- cpuid (0, eax, ebx, ecx, edx);
- /* We only look at the first four characters. */
- max_level = eax;
- if (max_level == 0)
- goto done;
- cpuid (0x80000000, eax, ebx, ecx, edx);
- ext_level = eax;
- if (ext_level < 0x80000000)
- goto done;
- cpuid (0x80000001, eax, ebx, ecx, edx);
- grub_cpuid_has_longmode = !!(edx & bit_LM);
- done:
- #endif
- cmd = grub_register_extcmd ("cpuid", grub_cmd_cpuid, GRUB_COMMAND_FLAG_BOTH,
- "[-l]", N_("Check for CPU features."), options);
- }
- GRUB_MOD_FINI(cpuid)
- {
- grub_unregister_extcmd (cmd);
- }
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