Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   David Laight <David.Laight@ACULAB.COM>
To:     'Christoph Hellwig' <hch@infradead.org>,
        "torvic9@mailbox.org" <torvic9@mailbox.org>
CC:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "x86@kernel.org" <x86@kernel.org>,
        "clang-built-linux@googlegroups.com" 
        <clang-built-linux@googlegroups.com>,
        "graysky@archlinux.us" <graysky@archlinux.us>
Subject: RE: [PATCH 2/2] x86, Makefile: Add new generic x86-64 settings
 v2/v3/v4
Thread-Topic: [PATCH 2/2] x86, Makefile: Add new generic x86-64 settings
 v2/v3/v4
Thread-Index: AQHXlAD0agS+R5TrUku3Pq8hTf8Ltqt7Yd3A
Date:   Thu, 19 Aug 2021 21:58:03 +0000
Message-ID: <b09a7be32cef407cb6b6361554411bda@AcuMS.aculab.com>
References: <269701460.117528.1629210189833@office.mailbox.org>
 <796036867.117557.1629210288168@office.mailbox.org>
 <YRyzhWJrqcRZkYRM@infradead.org>
In-Reply-To: <YRyzhWJrqcRZkYRM@infradead.org>
Accept-Language: en-GB, en-US
MIME-Version: 1.0
Content-Language: en-US
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8BIT
Precedence: bulk

From: Christoph Hellwig
> Sent: 18 August 2021 08:15
> 
> On Tue, Aug 17, 2021 at 04:24:48PM +0200, torvic9@mailbox.org wrote:
> > +	  Generic x86-64 CPU.
> > +	  Run equally well on all x86-64 CPUs with min support of x86-64-v2.
> 
> > +	help
> > +	  Generic x86-64-v3 CPU with v3 instructions.
> > +	  Run equally well on all x86-64 CPUs with min support of x86-64-v3.
> > +
> 
> > +	help
> > +	  Generic x86-64 CPU with v4 instructions.
> > +	  Run equally well on all x86-64 CPUs with min support of x86-64-v4.
> 
> How the f&%$% is a user supposed to know what these garbage descriptions
> are supposed to mean?

My thoughts.
I then looked up the link.
Most of the extra instructions are the AVX related ones.
They better not get enabled for a kernel build at all.

I wish I knew whether 'no-avx' actually implied 'no-avx2' and
all later avx options?
Or do kernel builds have to spot each new option and disable
in in turn?

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)