1 # ===========================================================================
2 # https://www.gnu.org/software/autoconf-archive/ax_gcc_x86_cpuid.html
3 # ===========================================================================
8 # AX_GCC_X86_CPUID_COUNT(OP, COUNT)
12 # On Pentium and later x86 processors, with gcc or a compiler that has a
13 # compatible syntax for inline assembly instructions, run a small program
14 # that executes the cpuid instruction with input OP. This can be used to
15 # detect the CPU type. AX_GCC_X86_CPUID_COUNT takes an additional COUNT
16 # parameter that gets passed into register ECX before calling cpuid.
18 # On output, the values of the eax, ebx, ecx, and edx registers are stored
19 # as hexadecimal strings as "eax:ebx:ecx:edx" in the cache variable
20 # ax_cv_gcc_x86_cpuid_OP.
22 # If the cpuid instruction fails (because you are running a
23 # cross-compiler, or because you are not using gcc, or because you are on
24 # a processor that doesn't have this instruction), ax_cv_gcc_x86_cpuid_OP
25 # is set to the string "unknown".
27 # This macro mainly exists to be used in AX_GCC_ARCHFLAG.
31 # Copyright (c) 2008 Steven G. Johnson <stevenj@alum.mit.edu>
32 # Copyright (c) 2008 Matteo Frigo
33 # Copyright (c) 2015 Michael Petch <mpetch@capp-sysware.com>
35 # This program is free software: you can redistribute it and/or modify it
36 # under the terms of the GNU General Public License as published by the
37 # Free Software Foundation, either version 3 of the License, or (at your
38 # option) any later version.
40 # This program is distributed in the hope that it will be useful, but
41 # WITHOUT ANY WARRANTY; without even the implied warranty of
42 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
43 # Public License for more details.
45 # You should have received a copy of the GNU General Public License along
46 # with this program. If not, see <https://www.gnu.org/licenses/>.
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63 AC_DEFUN([AX_GCC_X86_CPUID],
64 [AX_GCC_X86_CPUID_COUNT($1, 0)
67 AC_DEFUN([AX_GCC_X86_CPUID_COUNT],
68 [AC_REQUIRE([AC_PROG_CC])
70 AC_CACHE_CHECK(for x86 cpuid $1 output, ax_cv_gcc_x86_cpuid_$1,
71 [AC_RUN_IFELSE([AC_LANG_PROGRAM([#include <stdio.h>], [
72 int op = $1, level = $2, eax, ebx, ecx, edx;
74 __asm__ __volatile__ ("xchg %%ebx, %1\n"
77 : "=a" (eax), "=r" (ebx), "=c" (ecx), "=d" (edx)
78 : "a" (op), "2" (level));
80 f = fopen("conftest_cpuid", "w"); if (!f) return 1;
81 fprintf(f, "%x:%x:%x:%x\n", eax, ebx, ecx, edx);
85 [ax_cv_gcc_x86_cpuid_$1=`cat conftest_cpuid`; rm -f conftest_cpuid],
86 [ax_cv_gcc_x86_cpuid_$1=unknown; rm -f conftest_cpuid],
87 [ax_cv_gcc_x86_cpuid_$1=unknown])])