From: Thomas Gleixner <tglx@linutronix.de>
To: Borislav Petkov <bp@alien8.de>
Cc: Ingo Molnar <mingo@kernel.org>,
peterz@infradead.org, dave.hansen@intel.com,
torvalds@linux-foundation.org, piotr.luc@intel.com,
luto@kernel.org, brgerst@gmail.com, hpa@zytor.com,
linux-kernel@vger.kernel.org, dvlasenk@redhat.com,
jpoimboe@redhat.com, linux-tip-commits@vger.kernel.org
Subject: Re: [tip:x86/urgent] x86/cpufeature: Add AVX512_4VNNIW and AVX512_4FMAPS features
Date: Mon, 17 Oct 2016 09:55:10 +0200 (CEST) [thread overview]
Message-ID: <alpine.DEB.2.20.1610170952120.4912@nanos> (raw)
In-Reply-To: <20161016142233.xuqrahty6gcwq7en@pd.tnic>
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
next prev parent reply other threads:[~2016-10-17 7:58 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-12 17:57 [PATCH] " Piotr Luc
2016-10-16 11:21 ` [tip:x86/urgent] " tip-bot for Piotr Luc
2016-10-16 14:22 ` Borislav Petkov
2016-10-16 16:02 ` hpa
2016-10-16 16:35 ` Borislav Petkov
2016-10-16 18:42 ` hpa
2016-10-16 22:42 ` Borislav Petkov
2016-10-17 9:55 ` Luc, Piotr
2016-10-17 7:55 ` Thomas Gleixner [this message]
2016-10-17 8:20 ` Luc, Piotr
2016-10-17 8:47 ` Ingo Molnar
2016-10-17 9:53 ` Luc, Piotr
2016-10-17 9:54 ` Thomas Gleixner
2016-10-17 15:03 ` [PATCH v2] " Piotr Luc
2016-10-18 13:00 ` [v2] " Luc, Piotr
2016-10-18 13:08 ` Ingo Molnar
2016-10-18 15:01 ` [PATCH v3] " Piotr Luc
2016-10-19 15:43 ` [tip:x86/urgent] " tip-bot for Piotr Luc
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