SUMMARY: hung serial port, solaris 2.3

From: S. Cowles (
Date: Fri Jun 10 1994 - 02:14:33 CDT

Original problem:
Config: Sparc 10/41, Solaris 2.3, serial port splitter cable

I have two in/out modems on the A/B serial port of this sparc that
normally work very well. The B serial port is now hung following the
non-clean exit of one of our users from one of his dial-in sessions.
I've tried killing and restarting the sac and ttymon processes to free
the port back up, but have had no luck with this. How does one "clear"
a serial port on a Solaris box?

As an aside, could someone please tell me where the sac process is


After a few suggestions from the net, and an acknowledgement from Sun,
that yes, this is a problem under 2.3, I removed the existing port
monitors and service monitor, then recreated each of them. This in
itself did not unhang the port. Attempts to tip to the port (b) still
resulted in the message: all ports busy. However, calling in was now
possible. So, after initiating a dial-in session on the port, letting
it sit for a "while", then closing the session, the port was now
un-hung. (Resetting locks, somewhere?)

Attempts to disable/reenable the port with the serial manager out of
the admintool were not effective. Killing the sac and ttymon processes
were also not effective.

My thanks to the respondents.
From: (Dan Transue)
Paul Humphreys ( Postmaster ) paul@hydres.uucp
From: (Mike van der Velden [243])


ps. The sac process is respawned in /etc/inittab.

S. Cowles
voice: +1 415 812 1917
fax: +1 415 812 1916

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