After a little more investigation, I have a better idea where things
are going wrong in my attempts at booting a DECstation diskless.

The diskless(8) man page seems to imply that the kernel should NFS
mount the parent of the advertised (by bootparamd) root filesystem,
then use that to get the filehandle for the root filesystem; then do
the same for swap.  

NetBSD/pmax -current seems to want to mount the actual, advertised
root & swap filesystems.  However, NetBSD/pmax -current also doesn't
want to export a swap file..

Since all this code is machine-independant, does anybody know of any
other ports that are currently using diskless setups w/ -current?

Thanks,

Drew