Re: [RFC] framework for fpu usage in kernel

From: Manfred Spraul (
Date: Sun Feb 11 2001 - 15:30:53 EST

Alan Cox wrote:
> > memcopy is a really generic function, and calling it saves the current
> > fpu state into thread.i387.f{,x}save. IMHO that's wrong, memcopy must
> > save into a local buffer like raid5 checksumming.
> The mmx copy is only done in task context. There are a whole variety
> of _horrible_ problems doing it in interrupt space so based on the
> considerable number of problems with prior attempts to get it right on
> IRQ and copyuser cases I didnt bother
Even task context is dangerous:

What if a drm module wants to use the fpu and then uses memcpy() after
modifying the ftp registers?

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This archive was generated by hypermail 2b29 : Thu Feb 15 2001 - 21:00:17 EST