Tyan serial console - how?

Joe Kaiser jlkaiser at fnal.gov
Tue Nov 5 14:02:14 PST 2002

On Tue, 2002-11-05 at 14:36, David Mathog wrote:
> I've been trying to get the Tyan serial console working
> on our rack full of 2466 boards. So far only partial success.
> I've tried this:
> In the BIOS in the serial console section on node A set to:
> on Board ComA, direct, 115200, none, vt100, on
> In kermit on node B (linux) which will connect to A:
> set line /dev/ttyS0
> set speed 115200
> set flow none
> set watch-carrier off
> connect


A couple things:

If you are booting with lilo, 115200 won't work.  The highest we have
been successful with it is at 38400.

Serial console support needs to be enabled in the kernel.  This is
usually the default if you are booting with a stock RedHat kernel. 
Otherwise the:


parameters in your kernel config need to be set to "y."

There are also some lilo parameters that need to be set.  In your
lilo.conf file you can put the following if you have set the BIOS to do

append="console=tty0 console=ttyS0,38400"

Rerun lilo.

Then in /etc/inittab make sure you have something like this:

c:12345:respawn:/sbin/mingetty ttyS0

Then you should get output to the kermit process on the end of your
cable.  We have our consoles going to some sort of serial console port
thingy (Cyclades-Z, cyclades-Y, Lantronix SCS1600/3200) and then using
the conserver software to have a central management console and logging

If you want 115K then you will need to use grub not lilo.

If I got any of that wrong, please feel free to correct me.


Joe Kaiser

> Connect Com A of node A to Com A of node B with a null modem
> cable (6ft).
> Boot node A.
> Node A comes up, there's a quick flash in the kermit window,
> and it goes on to lilo/linux.  On the monitor also plugged into it
> I can see that the quick flash corresponds to the first screen
> of the boot sequence.  It was possible to get into BIOS setup by
> tapping F2 continuously on  node A's keyboard from reset or
> power up.  (By the time anything shows up on A's monitor it's
> always too late to hit F2 :-(.)  I've tried hitting the "F2" key
> in node B's kermit window, but the boot process ignores that and
> goes right on to lilo and linux.
> What must be typed in the serial console to break into the BIOS?
> Once in the bios there are squares (single letter size "pixels")
> dancing around the screen like "snow" on a TV.  Presumably the
> serial line protocol isn't set up quite right.  What should it
> have been?
> Is it possible to use the serial console to break into a 
> Tyan node which has locked up in linux?  By this, I mean
> something similar to the Sun console or the VMS console,
> where you can get in "underneath" the OS and force a
> reboot without having to cycle the power or hit the reset switch.
> Thanks,
> David Mathog
> mathog at caltech.edu
> Manager, Sequence Analysis Facility, Biology Division, Caltech
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Joe Kaiser - Systems Administrator                

Fermi Lab 
CD/OSS-SCS                Never laugh at live dragons.
jlkaiser at fnal.gov                                                

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