diff options
Diffstat (limited to 'grub-core/commands/i386/cpuid.c')
-rw-r--r-- | grub-core/commands/i386/cpuid.c | 100 |
1 files changed, 100 insertions, 0 deletions
diff --git a/grub-core/commands/i386/cpuid.c b/grub-core/commands/i386/cpuid.c new file mode 100644 index 0000000..6a771ba --- /dev/null +++ b/grub-core/commands/i386/cpuid.c @@ -0,0 +1,100 @@ +/* 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_MOD_LICENSE ("GPLv3+"); + +#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_context_t ctxt __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, 0, + "[-l]", N_("Check for CPU features."), options); +} + +GRUB_MOD_FINI(cpuid) +{ + grub_unregister_extcmd (cmd); +} |