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Date: Fri, 23 Feb 2001 13:44:14 -0800
From: "H. Peter Anvin" <hpa@transmeta.com>
Organization: Transmeta Corporation
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To: Quim K Holland <qkholland@my-deja.com>
CC: dledford@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org
Subject: Re: cpu_has_fxsr or cpu_has_xmm?
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Quim K Holland wrote:
> 
> DL> As to the correctness, the mxcsr register really only exists
> DL> if you have xmm, so the xmm is the correct test. However,...
> 
> DL> ...  User space programmers should be checking for xmm
> DL> capability themselves before ever paying attention to mxcsr
> DL> anyway, so it's not an end of the world error.
> 
> If that is the case, wouldn't it be simpler to always return
> tsk->thread.i387.fxsave.mxcsr from this function, and initialize
> that field to 0x1f80 (whatever that magic number means) when
> the structure is built?
> 

No, because the CPU *may* overwrite it when you do an FXSAVE.

	-hpa

-- 
<hpa@transmeta.com> at work, <hpa@zytor.com> in private!
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