linux-kernel - Re: [patch] x86, avx: don't use avx instructions with "noxsave" boot param

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Message-ID: <1343752022.3696.602.camel@sbsiddha-desk.sc.intel.com>
Date:	Tue, 31 Jul 2012 09:27:01 -0700
From:	Suresh Siddha <suresh.b.siddha@...el.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	NeilBrown <neilb@...e.de>, james.t.kukunas@...ux.intel.com,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [patch] x86, avx: don't use avx instructions with "noxsave"
 boot param

On Mon, 2012-07-30 at 21:33 -0700, H. Peter Anvin wrote:
> I'm wondering if we shouldn't just kill the affected CPUID bits if osxsave is off...

Yes, I considered clearing AVX bit (and any future xsave feature bits)
as part of the parsing "noxsave" parameter in x86_xsave_setup().

But thought checking for osxsave was more explicit and there are not
many places using avx code. Also, this follows the SDM guidelines and
sets a nice precedent for someone (app's) to follow in future.

I am ok either way!

thanks,
suresh

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