This question has been asked a few times, but never addressed.  After
building a new kernel, and installing it as /netbsd, the machine wouldn't
boot.  The bootloader gave the following:

-------------------------------------------------------------------------
Executing last command: boot
Boot device: disk  File and args:
NetBSD IEEE 1275 Bootblock
..>> NetBSD/sparc64 OpenFirmware Boot, Revision 1.5
>> (autobuild@cs20.apochromatic.org, Mon Apr  7 09:50:05 UTC 2003)
loadfile: reading header
unknown executable format
Program terminated
-------------------------------------------------------------------------

I messed with it a little while and it looks like the bootloader can't
read past a certain block on the disk.  I've reinstalled with a small /
and /usr on a separate partition, and my kernel that I built this morning
works fine.  Is this a known issue?  I haven't started using the machine
for anything, so I could definitely help test if needed.  Here are the
basic machine specs if it helps.

UltraAxe (IIi 300Mhz), 256M ram, symbios scsi controller and 9 gig scsi
hard drive.