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  • Hash : 16deb62f
    Author : Pádraig Brady
    Date : 2025-09-12T16:55:45

    cpu-supports: a module to honor GLIBC_TUNABLES=glibc.cpu.hwcaps
    
    This functionality is useful to allow better test coverage at least,
    and may be useful for users to tune their environment,
    avoiding CPU throttling for example.
    
    * lib/cpu-supports.h (cpu_supports): A new wrapper that
    checks that the GLIBC_TUNABLES environment variable allows
    the hardware feature, before checking with __builtin_cpu_supports().
    (cpu_may_support): Only perform the GLIBC_TUNABLES check,
    which is useful if using other interfaces like getauxval().
    (gcc_feature_to_glibc_hwcap): An internal helper that will resolve
    at compile time with standard optimizations enabled.
    * lib/cpu-supports.c (hwcap_allowed): Query the GLIBC_TUNABLES
    environment variable (read once per process), to see if the
    passed GLIBC_HWCAP is allowed.
    * modules/cpu-supports: New module definition.
    * modules/cpu-supports-tests: New test module definition.
    * tests/test-cpu-supports.c: New tests.