Re: drm fixup 2/2 - optimise i8x0 accesses..

[David S. Miller]

On Fri, 27 Aug 2004 15:13:54 +0100 (IST)
Dave Airlie <airlied@xxxxxxxx> wrote:

>    the patch below optimises the drm code to not do put_user() on memory the
>    kernel allocated and then mmap-installed to userspace, but instead makes it
>    use the kernel virtual address directly instead.

This might cause major problems on systems with virtually indexed
caches if precautions are not made at buffer allocation time such
that the virtual cache color of the kernel mapping is the same
as the user mapping.

Arjan, you should know better :-)

I also don't understand what this "optimization" is?  You don't need
a verify_area, therefore you can use __put_user() which amounts to
a load/store and an integer move instruction.
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