linux-kernel - Re: [PATCH 10/10] x86-32: panic on !CX8 && XMM

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Date:	Thu, 18 Feb 2010 01:46:59 +0100
From:	Luca Barbieri <luca@...a-barbieri.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	mingo@...e.hu, a.p.zijlstra@...llo.nl, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 10/10] x86-32: panic on !CX8 && XMM

> NAK in the extreme.
>
> This is not how we deal with these kinds of stuff.  If this really
> matters, we explicitly clear the CPU feature in the feature detect code.

The rationale is that a panic will likely be reported as a a bug and
this lets us know that such CPUs exist, which we may otherwise not
hear about.
The user may bypass the panic by altering the command line.

To avoid doing the panic, we could define an artificial "CX8_XMM"
flag, set it if CX8 && XMM and use that in the alternatives code in
the previous patch; this is a bit more intrusive.

We already manually set the CX8 flag on VIA CPUs that mistakenly not
report it, so that shouldn't be a problem.
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