Messages in this thread |  | | | From | (Eric W. Biederman) | | Subject | Re: [RFC] MMIO accessors & barriers documentation | | Date | Tue, 12 Sep 2006 00:27:57 -0600 |
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Benjamin Herrenschmidt <benh@kernel.crashing.org> writes:
> I've not gone too much in details about write combining (we need to do > something about it but I don't want to mix problems) but I did define > that the ordered accessors aren't guaranteed to provide write combining > on storage mapped with WC enabled while the relaxed or non ordered ones > are. That should be enough at this point.
Sounds good.
> Later, we should look into providing an ioremap_wc() and possibly page > table flags for write combining userland mappings. Time to get rid of > MTRRs for graphics :) And infiniband-style stuff seems to want that too.
ioremap_wc is actually the easy half. I have an old patch that handles that. The trick is to make certain multiple people don't map the same thing with different attributes. Unfortunately I haven't had time to work through that one yet.
Eric
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