* Luc, Piotr <Piotr.Luc@xxxxxxxxx> wrote: > On Mon, 2016-10-17 at 09:55 +0200, Thomas Gleixner wrote: > > 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/69/78/3194 > > > > 33-025.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. > > > The manual contains the typo in table 2.1 on page 2.2. > Please compare it to the detailed description of CPUID in table 4.8 on > page 2-16. > There manual groups both new bits under EDX: > > EDX Bits 01 - 00: Reserved > Bit 02: AVX512_4VNNIW (Vector instructions for deep learning > enhanced word variable precision.) > Bit 03: AVX512_4FMAPS (Vector instructions for deep learning > floating-point single precision.) > Bits 31-04: Reserved > > The typo was acknowledged and is going to be fixed in next version of > the document. All of this should be pointed out in the changelog. I've zapped the commit for the time being - let's iterate this once more, ok? Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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