e25482312e
add the range to the map, and use it for _bus_dmamap_load_{buffer,mbuf}.
- _bus_dmamap_load_mbuf: in the case of M_EXT_PAGES, deal with vm_pages
directly rather than doing pmap_extract on given kva.
as a side effect, do a segment coalescing and boundary checks for mbufs.
ok'ed by Frank van der Linden and Jason Thorpe on tech-kern@.