linux-kernel - Re: [PATCH 05/10] x86, xsave: make xsave_cntxt

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Message-ID: <4C471D37.4010208@zytor.com>
Date:	Wed, 21 Jul 2010 09:15:51 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Robert Richter <robert.richter@....com>
CC:	Suresh Siddha <suresh.b.siddha@...el.com>,
	Ingo Molnar <mingo@...e.hu>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 05/10] x86, xsave: make xsave_cntxt_init() static

On 07/21/2010 06:48 AM, Robert Richter wrote:
> On 20.07.10 18:20:24, Suresh Siddha wrote:
> 
>> Perhaps we can fold this patch into 
>> [PATCH 06/10] x86, xsave: do not initialize xsave in fpu_init()
>>
>> and probably do  fpu_init() first followed by xsave_init() so that
>> fpu_init() will set xstate_size based on fpu features and xsave_init()
>> can later overwrite xstate_size based on xstate features.
> 
> Yes, I will do this instead.
> 
> Lookin at this, I found that xsave is broken for (!HAVE_HWFP). This
> should be the case if config MATH_EMULATION and 'no387' kernel
> parameter are set and xsave exists. xsave will not work because
> x86/math-emu and xsave share the same memory. But this case can be
> treated as corner case. Maybe we should simply disable xsave then.
> 

Yes, I think we should.  It is *extremely* unlikely that any such real
hardware will ever be created at this point, and if so we can burn that
bridge when we get to it.

	-hpa

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

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