On Sun, 16 Oct 2016, Borislav Petkov wrote:
> > The spec can be found in Intel Software Developer Manual or in
> > Instruction Set Extensions Programming Reference. See
> > https://software.intel.com/sites/default/files/managed/69/78/319433-025.pdf.
>
> > +/* Intel-defined CPU features, CPUID level 0x00000007:0 (edx), word 18 */
> > +#define X86_FEATURE_AVX512_4VNNIW (18*32+2) /* AVX-512 Neural Network
> > Instructions */
> > +#define X86_FEATURE_AVX512_4FMAPS (18*32+3) /* AVX-512 Multiply
> > Accumulation Single precision */
>
> This is getting ridiculous: we keep adding new leafs to
> ->x86_capability, thus bloating cpuinfo_x86 but then it is not even
> worth it - this patch defines only two bits.
What's worse is that the Instruction Set Extensions Programming Reference
manual says:
CPUID.(EAX=07H, ECX=0):EDX[bit 02] AVX512_4FMAPS
CPUID.(EAX=07H, ECX=0):EBX[bit 03] AVX512_4VNNIW
So AVX512_4VNNIW is in EBX not EDX. What's correct here? The manual or the
patch?
I'm going to zap it.
Thanks,
tglx
