[Cbe-oss-dev] [PATCH 3/3] Cell IOMMU static mapping support
benh at kernel.crashing.org
Tue Jan 29 08:16:17 EST 2008
On Mon, 2008-01-28 at 10:23 -0600, Olof Johansson wrote:
> Ok, makes sense.
> I was going to protest the hack for >32GB configs, with the motivation
> that just using the htab-backed window is way too small for such a
> config. However, with 32GB memory and 4K pages, that window is 512MB, so
> we should be fine.
Might be a problem with 64K pages tho... Or do we use the same
In addition, on those blades, really the only device that is limited to
32 bits (and thus is forced to use the iommu remapped region) is USB.
> Having that described in the patch (or at least in the patch description)
> to make it more clear could be good. That, and the fact that the mapping
> is offset on <32GB memory machines, and thus not really a 1:1 mapping.
Should be called a "linear" mapping.
> Does the cell I/O bridge reflect out accesses to 2-4GB on the bus
> again? If not, that could be another place to stick the dynamic range
> for large config machines.
On the PCI bus itself, 2-4GB is where MMIO sits.
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