V6 [PATCH] x86: Add <sys/platform/x86.h>

[H.J. Lu]

On 10/25/18, Florian Weimer <fweimer@redhat.com> wrote:
> * H. J. Lu:
>
>> /* CPU_FEATURE_USABLE evaluates to true if the feature is usable.  */
>>  #define CPU_FEATURE_USABLE(name)                                  \
>>    ((need_arch_feature_##name                                      \
>>      && (x86_get_arch_feature (index_arch_##name##_Usable)         \
>>    & (bit_arch_##name##_Usable)) != 0)                             \
>>     || (!need_arch_feature_##name 	                           \
>>         && (x86_get_cpuid_registers (index_cpu_##name)->reg_##name \
>> 	    & (bit_cpu_##name)) != 0))
>
> I still think this is wrong.  This should be a const function, with a
> single argument, returning bool, so that we do not expose the internal

The only things exposed are

enum
  {
    /* The integer bit array index for the first set of internal feature
       bits.  */
    FEATURE_INDEX_1 = 0,
    FEATURE_INDEX_2,
    /* The current maximum size of the feature integer bit array.  */
    FEATURE_INDEX_MAX
  };

enum
  {
    COMMON_CPUID_INDEX_1 = 0,
    COMMON_CPUID_INDEX_7,
    COMMON_CPUID_INDEX_80000001,
    /* Keep the following line at the end.  */
    COMMON_CPUID_INDEX_MAX
  };

struct cpuid_registers
  {
    unsigned int eax;
    unsigned int ebx;
    unsigned int ecx;
    unsigned int edx;
  };

following the conventions of C/C++.

> implementation.  It will also be possible to use this function from Ada,
> Fortran, and so on.  This is not possible with a preprocessor macro.

This is designed for C/C++.  This is never intended for Fortran nor
Ada.  If there are requests for Fortran or Ada, we can investigate different
approaches for them.

Any other comments?

-- 
H.J.