Just a note on something that bit me here, when you are building a release 
(cd /usr/src/distrib ; make) the vax process creates the miniroot.fs file 
and mounts it using the vn driver. If something fails in the process of 
making the miniroot you will have to "reset" to zero by first unmounting 
/mnt and then unconfiguring (with vnconfig -u ) /dev/vnd0c otherwise when 
you restart the build you will get a device busy error and it won't work.

Another note is that the the netbsd.ram.gz file needs to be manually placed 
into the obj/distrib/miniroot directory, there doesn't seem to be a make 
rule to create it if it doesn't exist.

--Chuck