I just finished the first step towared a port of the xd and xy drivers
that Chuck Cranor wrote for the sparc.  They compile now, but have not
been tested. (I don't even know if the resulting kernel boots! 8^)

It would be great if someone with an xd and/or xy board could build the
SMD_TEST kernel and do some debugging, testing, etc.

The files are all on sup.netbsd.org now:

conf/SMD_TEST
sun3/disksubr.c
dev/xd.c
dev/xdreg.h
dev/xdvar.h
dev/xio.h
dev/xy.c
dev/xyreg.h
dev/xyvar.h