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-   -   Login app appears to be crashing on ttyS0 (

jrog 07-17-2006 12:33 PM

Login app appears to be crashing on ttyS0

This is my first post, and I've searched high and low and can't seem to find a solution. I have a Linux SBC that I want to run more "embedded", and to me, that means Serial port console instead of VGA and keyboard.

I'm running RHEL4, and I went through the process of loading the grub.conf file:

cat /etc/grub.conf
# grub.conf generated by anaconda
# Note that you do not have to rerun grub after making changes to this file
# NOTICE: You have a /boot partition. This means that
# all kernel and initrd paths are relative to /boot/, eg.
# root (hd0,0)
# kernel /vmlinuz-version ro root=/dev/VolGroup00/LogVol00
# initrd /initrd-version.img
serial --unit=0 --speed=9600
terminal --timeout=2 serial console
title Red Hat Enterprise Linux ES (2.6.9-11.EL)
root (hd0,0)
kernel /vmlinuz-2.6.9-11.EL ro root=/dev/VolGroup00/LogVol00 console=tty1 console=ttyS0,9600
initrd /initrd-2.6.9-11.EL.img

Then, I edited my /etc/inittab to include the agetty console:

S0:2345:respawn:/sbin/agetty -L ttyS0 9600 vt100

And I added the line to /etc/securetty for ttyS0. I can get the console to display the entirety of the login information, and the keyboard works in grub to hit enter and continue instead of waiting for the 5 second timeout. My problem, is that once the login window kicks open, I can't type anything. I can SSH into the box, and kickstart the agetty process, and then that re-launches the login program on the serial port, and it shows my text that I tried to type. Very odd, but it's as if the login app has crashed, or at least is not taking my characters. Has anyone encountered this?

I know it's not a cable issue, as I can send text down and back. Is there another sort of login process I can invoke that might work?

Thanks for the suggestions in advance, I appreciate it.


blackhole54 07-20-2006 08:01 AM


I've used getty for serial login (not an embedded system) but not agetty. This is just a thought that might get you started looking in the right direction (or not). I wonder if the type of parameters that can be set with stty are not right. (Obviously you are not going to actually use stty in this circumstance.) With getty these parameters are set in the /etc/gettydefs file. I would guess there is a similar file for agetty.

If it is of any use, the /etc/gettydefs line I use (mine is set for 115200 baud) is


# 115200 fixed baud Dumb Terminal entry
DT115200# B115200 CS8 CLOCAL # B115200 SANE -ISTRIP CLOCAL #@S login: #DT57600

Good luck!

P.S. Long live the serial log in!;)

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