On Thu, Dec 13, 2007 at 09:23:26PM -0700, Eric W. Biederman wrote:
> [email protected] (Eric W. Biederman) writes:
> Ok. My analysis here was wrong. Currently pgprot_noncached and
> ioremap_nocache are out of sync. With ioremap_nocache only specifying
> _PAGE_PCD and pgprot_noncached specifying _PAGE_PCD | _PAGE_PWT.
>
> So I don't have a clue how someone could reprogram the mtrrs currently
> and expect things to work.
>
> ...
>
> If we bother to ask ioremap for memory that is not cached, the last
> thing in the world we want is the MTRRs upgrading that to write combining.
> So ioremap_nocache has been slightly buggy for ages. ioremap_nocache
> and PAGE_KERNEL_NOCACHE should get _PAGE_PWT added to their
> definitions.
>
> Could we please get a cleanup patch at the beginning of this patchset
> or that comes before it that fixes ioremap_nocache on x86?
>
> That will make us a lot more git-bisect safe.
Ok. I will send a separate patch fixing ioremap_nocache on x86.
thanks,
suresh
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