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From: "Yu, Fenghua" <fenghua.yu@intel.com>
To: Borislav Petkov <bp@alien8.de>,
        "Kammela, Gayatri" <gayatri.kammela@intel.com>
CC: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
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        "Neri, Ricardo" <ricardo.neri@intel.com>,
        "Zhong, Yang" <yang.zhong@intel.com>
Subject: RE: [PATCH v2]  x86/cpufeatures: Enable new SSE/AVX/AVX512 cpu
 features
Thread-Topic: [PATCH v2]  x86/cpufeatures: Enable new SSE/AVX/AVX512 cpu
 features
Thread-Index: AQHTUjAA/9Nsz1zP/kWB1VQZPwjC1qL+PjsggAAHDUA=
Date: Tue, 31 Oct 2017 18:25:55 +0000
Message-ID: <3E5A0FA7E9CA944F9D5414FEC6C712207589C94F@ORSMSX106.amr.corp.intel.com>
References: <1509412829-23380-1-git-send-email-gayatri.kammela@intel.com>
 <20171031100619.q5asiqkbuqi2cecp@pd.tnic> 
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> On Tuesday, October 31, 2017 11:03 AM, Yu, Fenghua wrote
> > On Tuesday, October 31, 2017 3:06 AM, Borislav Petkov wrote:
> > On Mon, Oct 30, 2017 at 06:20:29PM -0700, Gayatri Kammela wrote:
> > >  #define X86_FEATURE_AVX512VBMI  (16*32+ 1) /* AVX512 Vector Bit
> > Manipulation instructions*/
> >
> > So we have previous AVX512 feature bits which do not separate AVX512
> > with a "_" but the new ones do. I think we should unify this and the
> > SDM should be fixed too.
> 
> This patch exactly follows the names in the spec.
> 
> As you said, the legacy code doesn't follow spec naming strictly and the spec
> doesn't have uniform naming convention either. We are contacting spec
> author to see if we can follow the same naming convention in the future
> specs.

The spec author doesn't want to change the legacy names to insert "_" in order to have uniform names. The "_" in a name is just for readability. So in the future specs, there will be mixed names, some with "_" and some without "_".

We may need to send a patch to fix a few legacy names that don't match exactly specs, e.g. AVX512VBMI as you mentioned.

Thanks.

-Fenghua