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Date: Sun, 30 Jul 2006 21:28:42 +0300
From: Avi Kivity <avi@argo.co.il>
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To: Jan Engelhardt <jengelh@linux01.gwdg.de>
CC: Jiri Slaby <jirislaby@gmail.com>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: FP in kernelspace
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Jan Engelhardt wrote:
>
> > kernel_fpu_begin();
> > c = d * 3.14;
> > kernel_fpu_end();
>
> static inline void kernel_fpu_begin() {
>     ...
>     preempt_disable();
>     ...
> }
>
Is the kernel allowed to clobber userspace's sse registers?

What about interrupt code?

xor.h at least appears to save the sse state before use.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.