[Soekris] net4801 lockups with serial switch

[Michael Smith]

Hi,

I saw the recent message about a BIOS fix for a serial bug on the 4501 and
I'm wondering if it might be related to a problem I noticed with a couple
of net4801s.

I had a stack of 2 4501s and 2 4801s plugged into a 4-port serial
switchbox, each running Linux 2.4.20 and a 57600 bps serial console. I
was running Minicom on a PC on the other end of the switchbox.

I could get the 4801s to lock up occasionally by running a command on the
console to generate a lot of output. They locked up even more often if the
switchbox was switched from their console to another unit. The units
froze completely (no response on the serial console, and no response on
the network). The 4501s didn't have this problem.

I couldn't reproduce it when the 4801s were connected directly instead of
through the switchbox, so I figured it might be an electrical problem -
apparently most switchboxes don't keep all the ports grounded. Still, it
worries me a little because the 4501s didn't seem to care.

Has anyone else seen this behaviour? I'm using 1.25 mA, 24-36V power
supplies so I don't think it's a power problem.

Mike