I unearthed my sun3x last night, and pulled down enough of NetBSD to see if
it would boot diskless (netboot + kernel).  Unfortunately, it didn't work.
It everything looked ok up to the esp0 configuration, and then slightly
after it.

The boot looked something like (from memory):

...
normal boot stuff/device probes
...
esp0: blah blah
esp0: SCSI Bus Reset
esp0: SCSI Bus Reset
esp0: SCSI Bus Reset
esp0: SCSI Bus Reset
esp0: SCSI Bus Reset
esp0: SCSI Bus Reset
esp0: SCSI Bus Reset
esp0: SCSI Bus Reset
esp0: SCSI Bus Reset
...
more device probes
...
esp0: SCSI Bus Reset
esp0: SCSI Bus Reset
esp0: SCSI Bus Reset
esp0: SCSI Bus Reset
esp0: SCSI Bus Reset (scrolling for a long time)

I'm fairly sure the SCSI controller in this machine is shot, and I was
wondering whether some kind soul could build a kernel for me that completely
leaves the esp0 (and all scsi support) out.  My guess is that the machine
will work even with the dead SCSI controller if I had a kernel that didn't
mess with it =)

This could also be a bug in NetBSD/sun3x, but my suspicion is that it's
my problem since I didn't see any PR's about this.

--Jason