network hangs I/O system?

Thomas Doerfler Thomas.Doerfler at
Mon Apr 2 06:42:24 UTC 2001


in my current project my customer has found out a very strange 
behaviour: I have built a system based on RTEMS-4.0.0 including 
ethernet networking, hardware is the MC68360. 

When my customer powers my systems up with disconnected network, they 
run fine for many days. When my customer connects my systems to his 
plant network (with rather heavy load and a high broadcast rate), 
then the systems hang after some time, although they themselfs are 
more or less idle (waiting for a connect from the network). It takes 
between 2 hours and 5 days, before the systems hang. Some internal 
tasks still seem to run (e.g. task to retrigger of software watchdog 
:-(( ), but all the I/O activity (including serial V.24 devices) is 
inactive. (Even a disconnect from the network does not wake the 
systems up again, only a power cycle helps.)

In my local office network (with much lower traffic) I could not 
repeat this error. 

Now my questions: 

- Did anybody out there find the same behaviour during development 
(or test phase)?

- Is it possible that the "multiple event bug" discussed recently (by 
Zoltan etc.) can cause this behaviour concerning the network task?

- Is it possible that the network task falls into a condition so that 
it consumes all CPU performance, even when there is no more traffic 
on the network connector?

- Is there any "global I/O" semaphore that might block the whole I/O 
system (networking, serial termios drivers AND serial non-termios 

Any hints welcome :-)


IMD Ingenieurbuero fuer Microcomputertechnik
Thomas Doerfler           Herbststrasse 8
D-82178 Puchheim          Germany
email:    Thomas.Doerfler at

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