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Date: Sat, 1 Jun 1996 20:17:46 -0300 (EST)
From: "Lenzi, Sergio" <lenzi@cwbone.bsi.com.br>
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To: Marc van Kempen <marc@bowtie.nl>
cc: hackers@freebsd.org
Subject: Re: Problems with serial port
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On Fri, 31 May 1996, Marc van Kempen wrote:

> 
> Hi,
> 
> I'm having a problem with sendfax (from mgetty 0.99) hanging in a 
> ttywait (used ps auxl). This seems to happen to me after the machine
> has been up for a longer period (19 days in this case, it also
> happened a while back. The machine had been up for a similar period).
> 
> I don't seem to able to get out of it, short of rebooting. This is 
> on a -stable kernel from a while back, rest is 2.1.
> 
> Is there any other solution to remove the proces and free the 
> serial port, other than rebooting and is this perhaps a hardware
> problem? (Whenever I reboot, the problem is immediately gone.)
> 
> Regards,
> Marc.

The problem seems to happen when the fax disconnects and the modem sends 
erratic data to the port, causing it to hang. (i have experienced this 
whith modems in a kermit program).
Solution: use the comcontrol command and the drainwait options.
ex: comcontrol /dev/cuaa1 drainwait 20

In  my system the port returns to normal state in 20 seconds.


Hope this will help.>