map. Use this new feature to implement iommu_dvmamap_load_mbuf() and
iommu_dvmamap_load_uio() functions in terms of a new helper function,
iommu_dvmamap_load_buffer(). Reimplement the iommu_dvmamap_load()
to use it, too.
This requires some changes to the map format; in addition to that,
remove unused or redundant members.
Add SBus and Psycho wrappers for the new functions, and make them
available through the respective DMA tags.
_nexus_dmamap_load_buffer()
- implement nexus_dmamap_load() in terms of _nexus_dmamap_load_buffer().
Note that this is untested, as this code is not currently used (but
might be later for UPA devices).
- move BUS_DMAMAP_NSEGS to bus_private.h
- disable the ecache flushing in nexus_dmamap_sync(); it should not be
needed, although the docs are not entirely clear on that.
- change the IOMMU support code so that it supports overcommittting the
available DVMA memory, while still allocating as lazily as possible.
This is achieved by limiting the preallocation, and deferring the
allocation to map load time when it fails. In the latter case, the
DVMA memory reserved for unloaded maps can be stolen to free up enough
memory for loading a map.
- allow NULL settings in the method tables, and search the parent tags
until an appropriate implementation is found. This allows to remove some
kluges in the old implementation.
