In article <1992Aug25.215550.26919@athena.mit.edu> tytso@ATHENA.MIT.EDU (Theodore Ts'o) writes:
quoted text
>   From: satishc@microsoft.com (Satish Chittamuru)
>   Date: 25 Aug 92 02:11:42 GMT
>
>    > Does anyone else have problems with Linux not correctly "shutting down"
>    > the 16550?  Ever since the kernel has supported a 16550, I have had to
>    > hard reset the computer after running linux, or it seems that the
>    > computer "forgets" that the port that contains the 16550, exists.
>
>   I have always had this problem. I usually just hard reboot if I need
>   to use the modem again. Would be nice if this could be fixed.
>
>Once I have time to recover from moving to a new apartment, I'll make
>changes to the version of the serial driver I've been working on to
>shutdown the 16550A FIFO's upon device close, instead of leaving the
>FIFO's enabled the whole time.  I think this should fix the problem.
>
>                                               - Ted
>

I've been having problems with 16450's in my two Linux machines.  I haven't
noticed it with my serial mouse, but my modem lines get forgotten my
Linux.  It doesn't happen all the time, so it is unpredictable.  I will
be connected somewhere, then all of a sudden get a little line noise and
the serial port goes dead.  If I disconnect the phone line quick enough,
I can sometimes drop carrier and regain my serial port.  Otherwise, it
is dead until I reboot.  This has happened with an internal modem in both
of my machines, and with an external modem in my 386DX.  I can "cat" files
to the serial ports after this has occured, but the modem light don't
come on so it acts like a "bit bucket".  I don't get any "busy" messages
or any kind of errors, I just can't use the ports.  "stty sane" doesn't
do it.  

Has anyone else encountered this problem or have any suggestions for getting 
around this?  I hate to reboot the machine each time I lose the serial port.

I had originally thought it was just the internal modem, but it must be
Linux because it happens with more than one serial port on more than one
machine.  I use 16450's only.

Thanks for any help,


-- 
Jim H.
*
* James L. Henrickson
* ujlh@sunyit.edu        "Some day I might have a real .signature!"