I recently installed NetBSD 1.4.2 on an old Mac IIsi. The IIsi has an FPU 
and 8 megs of RAM. There are also 7 drives attached to it, 5 are CDROM 
drives while the other two are hard drives (of which one is a Quantum 80MB HD).

The problem I'm having is that the machine can't run reliably at all. Right 
after booting up, before I can even log on, often several programs have 
already dumped core. The actual programs themselves seem to be random, from 
inetd and portmap, to csh and even init(!). Other times, the machine 
reports a bus error or illegal instruction, and the kernel panics. 
Sometimes the machine will even just lock up hard and require a power 
cycle. The SCSI chain has worked fine in MacOS for a while, so I don't 
believe it's a hardware error.

This seems to be a problem with the NCR SCSI driver, as when I use the SBC 
kernel, everything is right in the world and all of these problems go away. 
I would use the SBC kernel, except for the fact that many of the CDROM 
drives won't work under it. The SBC kernel seems to be much pickier about 
SCSI parity than the NCR driver, as I can access all of the CDROM drives 
fine using NCR, but with SBC, I get lots of errors like:

sbc0: parity error!
sbc0: parity error!
sbc0: parity error!
sbc0: parity error!
sbc0: reset SCSI bus for TID=6 LUN=0

and then none of those drives are accessible.

All of the drives that the SBC driver complains about are of the same make, 
and fairly crusty and old (NEC-25R single speed SCSI-1 drives), however 
they are fine for my purposes. Usually there is a dip switch on SCSI drives 
somewhere that let you toggle parity, but unfortunately these drives have 
no such toggle.

Does anybody have any suggestions on how to make this system usable? I'm 
currently running generic -- is there any way for my to compile a new SBC 
kernel that isn't sensitive to parity?

Leonard

--
Leonard Chung - <leonard@ssl.berkeley.edu>
SETI@home - The Search for Extraterrestrial Intelligence @ home
http://www.setiathome.ssl.berkeley.edu