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CPUID Build status License: ISC

"cpuid" is a very simple C program, designed to dump and extract information from the x86 CPUID instruction.

cpuid is capable of dumping all CPUID leaves (except any unknown leaves which require special ECX values to dump all information). cpuid can only decode certain leaves, but this functionality will be expanded as the CPUID specifications provided by AMD and Intel change.


The build process is simplified compared to a plethora of other open source projects out there. You don't need autoconf/automake or any of the headaches that go along with those tools.


  • C compiler (GNU C Compiler, LLVM/Clang, Microsoft Visual C++, and the Intel C++ Compiler are known to work)
  • Perl 5.8 or later

And one of:

  • GNU Make 3.80 or later
  • Meson 0.50 or later

Depending on whether you have GNU Make or Meson, do one of:

$ meson . build
$ ninja -C build


$ make

And you should have a new executable called 'cpuid' in a few seconds.


Since the usage will likely change over time, I recommend that you take a look at the output of:

$ ./cpuid --help

Reporting Bugs

If you find a bug in CPUID, please submit details about it to the issue tracker on GitHub.

If the bug is regarding the decoding or dumping of CPUID details, then you should include the dump.txt and decode.txt generated with these commands:

$ ./cpuid -d -c -1 > dump.txt
$ ./cpuid -c -1 > decode.txt

You should also specify what revision of CPUID you are running. If you don't know, you can find out with:

$ ./cpuid --version

Reference Documentation

You can find current Intel and AMD CPUID specifications at these locations:

I try to keep up with these as they change, but sometimes I'm slow on the uptake. Please notify me if you notice any inconsistencies or if features you find relevant are not being decoded.


I'm reachable via email and respond frequently.

Steven Noonan <>