Re: [PATCH 0/8] MR5346: Support generic xstate (part 3).

[Jacek Caban (＠jacek)]

Jacek Caban (@jacek) commented about dlls/ntdll/unix/system.c:
>          do_cpuid( 0x0000000d, 1, regs3 ); /* get XSAVE details */
>          if (regs3[0] & 2) xstate_compaction_enabled = TRUE;
> -
>        xstate_supported_features_mask = 3;
> -
>        if (features & CPU_FEATURE_AVX)
> -
>            xstate_supported_features_mask |= (UINT64)1 << XSTATE_AVX;
> -
> -
>        do_cpuid( 0x0000000d, 0, regs3 ); /* get user xstate features */
> -
>        xstate_supported_features_mask = ((ULONG64)regs3[3] << 32) | regs3[0];
> -
>        __asm__ volatile
> -
>        (
> -
>            "xorl %%ecx,%%ecx\n\t"
> -
>            "xgetbv\n\t"
> -
>            "movl %%eax,%0\n\t"
> -
>            "movl %%edx,%1\n\t"
> -
>            : "=m"(regs3[0]), "=m"(regs3[1]) : : "eax", "ecx", "edx"
> -
>        );

It would be nice to avoid inline assembly like that. I guess we can't use builtin `_xgetbv` for compatibility reasons, but I guess we could have its local implementation, similar to `do_cpuid`.