Re: Diagnosing serial ports

["nate" <debian-user@aphroland.org>]

<quote who="Andrew Perrin">

> I'm beginning to wonder if some other process has locked up the serial
> port (although fuser -v /dev/ttyS1 shows nothing) or if I'm missing some
> module or kernel option.  I know this is speculative, but if anyone's got
> an idea I'd be very grateful.
>
> This is woody running custom-built kernel 2.4.18.


i had a similar problem with this server im using, trying to get a
serial console., it drove me up the $#$%@ wall for months. finally
on tuesday night it failed again(ethernet card errors), so i went
in, and tried getting serial console to work agian, wouldn't work.

so i ran strace on the getty process, and turns out I did have a serial
console, i just could not see anything on the remote end, i managed
to login and issue commands, but the remote terminal was always blank.

i guess one of the pins is bad on the com port, once i switched to another
com port(had to crack the case and install one, damn board doesn't have
2 onboard ports), it worked immediately.

so try strace, see if you see data being sent. it should also tell you
if for some reason it cannot open the serial port.

and if you have anything else to use on the serial port to verify
that it's working(e.g, enabled in bios, and kernel detects it properly
at the right i/o and irq address) that would be good. if your board
has 2 serial ports you could do a serial console to the other port,
with a null modem cable..just edit /etc/inittab, change the line that
says for serial console and to telinit q, you should get a serial console.

or if you have a modem or other serial device..

good luck

nate




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