On Pentium and later x86 processors, with gcc or a compiler that has a compatible syntax for inline assembly instructions, run a small program that executes the cpuid instruction with input OP. This can be used to detect the CPU type.
On output, the values of the eax, ebx, ecx, and edx registers are stored as hexadecimal strings as "eax:ebx:ecx:edx" in the cache variable ax_cv_gcc_x86_cpuid_OP.
If the cpuid instruction fails (because you are running a cross-compiler, or because you are not using gcc, or because you are on a processor that doesn’t have this instruction), ax_cv_gcc_x86_cpuid_OP is set to the string "unknown".
This macro mainly exists to be used in AX_GCC_ARCHFLAG.
Download the latest version of ax_gcc_x86_cpuid.m4 or browse the macro’s revision history.
Copyright © 2008 Steven G. Johnson email@example.com
Copyright © 2008 Matteo Frigo
This program 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.
This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
As a special exception, the respective Autoconf Macro’s copyright owner gives unlimited permission to copy, distribute and modify the configure scripts that are the output of Autoconf when processing the Macro. You need not follow the terms of the GNU General Public License when using or distributing such scripts, even though portions of the text of the Macro appear in them. The GNU General Public License (GPL) does govern all other use of the material that constitutes the Autoconf Macro.
This special exception to the GPL applies to versions of the Autoconf Macro released by the Autoconf Archive. When you make and distribute a modified version of the Autoconf Macro, you may extend this special exception to the GPL to apply to your modified version as well.