In response to the following two posts, I had noticed the same problem---
when I scanned the entire cd-rom's data for validity, the system would always
crash, without any messages or warning.  This happened with the DEC RRD42.

When I substituted a newer generic scsi cd drive, the problem did not occur,
and all 650MB of data was read successfully!

So, I would guess there is some strangeness with the RRD42 which NetBSD is
not taking into consideration.

I can help with this project when I return to my machines in a week from now.

I didn't report this since I am having other serious problems with my machine
which cause gcc to fail.  Its a 5000/200, and I assumed that the cd problem
was related to those other problems.  Perhaps they are and we both have
problematic machines.

>> On Apr  5,  7:46pm, mjbedy wrote:
>>   dd if=/dev/rz4a of=/dev/null
>> 
>>   I did this a couple times (I was basically amused that I had a singel
>> speed CD-ROM - it says it's an RRD42, or something similar to that - I'm
>> not sitting next to it right now.) Suddenly, BOOM, the system rebooted.

>  This sounds like it might be the SCSI driver getting in trouble and
>rebooting the system when it gets an unexpected condition.  It can't
>reasonably do a panic() at that point, since the driver state is in the
>middle of an operation and the driver doesn't know how to reset things.

>  Most of the places where the driver will reboot the system will now
>display a message with some information about what it found wrong (with
>the idea that I might be able to glean enough information about the problem
>to figure out how to recover from it).  There is one place where no message
>is displayed unless the kernel was configured with DEBUG (which is not
>the case with the GENERIC kernel).

>> I'll see if a can reproduce it later. I have the kernal sources, so I can
>> compile a new one if need be - is there a way to get it to drop into a
>> debug mode instead of rebooting if Something Bad happens?