> What if a drm module wants to use the fpu and then uses memcpy() after
> modifying the ftp registers?
Interesting question. Right now the answer is dont do that. Point noted
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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
>
> 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
Currently there are 2 fpu users in the kernel:
raid5 checksumming and 3dnow memcpy/memset.
raid5 checksumming is not problematic, but _mmx_memcpy() has unexpected
side effects if someone else is also using the fpu:
memcopy is a really generic function, and calling it saves the current
fpu state i
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