Response Summary - The Cure for "link down" Found

[Manabu Tokunaga [c100]]

A few weeks ago, I have posted a question as follows, and the cure is found.

System   :   Sun/3 180  Sun OS 4.0.1
Problem  :  /dev/cua* occasionally goes into "link down" mode.
Diagnosis:

 o There is no LCK_* file in /usr/spool/uucp. "tip" | uucp is not running.
 o Modem is working/ready. Power cycling it does nothing.
 o Likely to happen when tip is killed externally by a user (i.e. kill -9)
 o Subsequent tip execution results in "link down" messages from the system.

The Cure:

 o Do a ps and look for <exiting> processes.
 o Perform 
	trace -p <pid>
or
	gcore <pid>

Discussions:

Some participants have also discovered that this happens when a serial
device (printer) connected to the cua* sends XOFF and then the tip is
killed.  At Imatron, we also found that a getty goes in <exiting> when a
video terminal user inadvertently presses CTRL-S and kills the login shell
from another terminal in panic. XOFF has another profound effect - about a
year ago we could not boot our Sun no matter what we did (reseated boards,
checked disks). A few hours later we found out that console VT-100 was in
XOFF mode.

I thank you for all participated in this topic.

Manabu Tokunaga, CS Dept. UltraFast CT Development Group/ Imatron Inc.
389 Oyster Point Blvd., South San Francisco, California 94080
Phone: 415-583-9877 X407