I don't know if anyone cares or not but if you do I found vsbus_dma_start. 
Apparently Ragge's incorporation of the MFM stuff hit "mid-tag" as it were 
and some of the files in the main branch are needed in the 1.5 branch. In 
particular it seems that vsbus.c and vsbus_dma.c in the main line are more 
up to date than the netbsd-1-5 branch tag. I've merged them in and I'm 
going to see if I can get a bootable kernel out of it.

--Chuck