8808-type Packets after Unrelated Crash

Stephen Wynne stevemw@mindspring.com
Sun Jan 31 13:16:05 1999


First, I'd like to thank the developers for this driver and say that
it normally does an excellent job of keeping my system on the network.

Although it initially wasn't the eepro100 driver to blame, I recently
took down our entire network at work (involving a Cisco router) when
my system crashed and began spewing type ethernet type "8808" packets. 
Whatever the initial rate, it settles down to about one per second,
but it's enough to keep the router very confused. I don't know much
more than that since I don't manage the network gear where I work.

The crash was caused (and the details are unclear to me) when part of
an unrelated kernel module we're developing dereferenced a null
function pointer. I have no idea what happened right before that
or afterward. I can reproduce the problem, however.

Does anyone have any tips for learning more about how to debug this
sort of thing? I was reduced to running some cheap DOS-based software
for sniffing Ethernet packets as I worked to try to isolate the
problem, but it was still ineffectual in helping to determine what the
kernel was actually doing (since my whole system was locked up).

I know where to go in the kernel to see what happened approximately up
until the crash occurred, but I don't know how to actually debug right
on through it. Moreover, the "oops" we managed to capture wasn't very
helpful (lots of stuff was missing, including the EIP).

Any tips would be appreciated, although this is mostly an academic
exercise at this point. Again, I'm looking for answers to these

1. How to better debug these kinds of Linux kernel faults?
2. What could cause an eepro100 on a 10mbit network to start spewing
   '8808' type packets?
3. Are the eepro100 developers interested in adding some resilience
   in this kind of situation? (If it's even possible.)

Because I feel there's so much for me to learn in this problem, I'd
be happy for the opportunity to work with you on this, if it seems
at all productive.

Thank you,