Re: [patch] x86, avx: don't use avx instructions with "noxsave" bootparam

[H. Peter Anvin]

On 07/31/2012 09:27 AM, Suresh Siddha wrote:
> 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!

My main reason for thinking that it would be good to clear the bits is 
that it plays a lot nicer with alternatives and with static_cpu_has().

	-hpa


--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/