On Wed, 27 Aug 1997, Paul Kranenburg wrote:

> In order to take full advantage of cache-coherent DVMA, the routines that
> load the IOMMU page tables should changed to allocate DVMA addresses
> that are congruent to kernel virtual addresses mapping the same physical
> page(s).
> 
> I was looking at the extent_*() routines to assist with this, but it
> doesn't seem to directly support this type of resource allocation.

We had to do this for the sun3x, since it has as an IOMMU as well.  Our
solution was to use a resource map, rather than an extent map.
 
-J