I've just committed some new code to help support drivers that
need to do bus-master access to main memory (in DVMA space).
Those working on the XY driver should take a look at
  sun3/vm_machdep.c: dvma_remap(), dvma_unmap()

While I was at it, I fixed a bug caused by confusion over the
size of DVMA alloctions (bytes vs. pages) that would cause the
mappings made by bus_mapin() in phys_map to be overwritten.

I just updated the read-to-go kernel to contain these changes.
(ftp.netbsd.org://pub/NetBSD/arch/sun3/netbsd-gen.gz)

Gordon