[PLUG] Problems setting up a linux system as a serial console

[Cy TROic <cytroic@netaxs.com>]

Anyone here use any linux boxes as a serial console? If so, maybe you can
help me out... 

Intro:
-=-=-=
	I'm having problems setting up a my first linux box on a intel
platform as a serial console. I've consulted some personal documention
someone in our company wrote up, as well as Serial-HOWTO and
Text-Terminal-HOWTO


Background:
-=-=-=-=-=-

Our company is doing more and more remote consoles, such tip hardwire's
between sun boxes (db-29 DTE's), mincom session from a linux box (db-9) to
a sun box (again, db-29 DTE). A few months ago we installed some digi
terminal servers (serial and ethernet), and hooked out sun boxes to them
(using DB-29 DCE's), and it works great. Now the next step is to hook up a
serial console to our linux boxes so they also can be connected to the
terminal servers. Before we do that, we are trying a basic serial console
and connecting from another linux box via minicom. 

We have not gotten it to work yet, and the big stumper is that we are
somewhat experienced at serial consoles on other OS's bases on what we
already have setup. In addition, someone else in our company (another
location in the country) has gotten it to work great. They have provided
documentation on how to do it, but it has not helped...

Documention: for setting up on a particular terminal server. (only
included intro section- that's all I am working on)


Putting the Linux console on a serial port

[snip] 

The Process

  1. Install a kernel with support for putting the console on a serial port.
     When you run "make xxxconfig", look for the appropriate setting in the
     "Character Devices" section (CONFIG_SERIAL_CONSOLE in the kernel config
     file). If you're running a fairly recent (e.g., Redhat 6.2) version of
     Linux however, there's a good chance this isn't even necessary; it's
     probably compiled in.

     An easy way to tell is to do all the other setup, and then see if your
     console is on a serial port. If it's not, you need to install a new
     kernel. :)

  2. Tell Linux to put the console on a serial port. This is done in one of
     two ways: either remove any and all video cards from your system (not
     recommended), or change /etc/lilo.conf (recommended).

     If you want to change /etc/lilo.conf, find the stanza for the image you
     boot (usually this is the group of lines after "image=linux" in the
     file), and add a line that reads:

          append="console=ttyS0"

     Of course, if you want to use the second serial port, then use ttyS1,
     and if you already have an append line, then add this parameter to it.

  3. Run a login process on the serial port. Chances are that you want to be
     able to log into the console, rather than just watch messages scroll
     by, in which case you should find the section of /etc/inittab which
     starts up gettys on the virtual terminals, and add a line which starts
     one up on the appropriate serial port.

     For example, find a section that looks like this:

          ...
          5:2345:respawn:/sbin/mingetty tty5
          6:2345:respawn:/sbin/mingetty tty6

     And add a line like the one shown in bold below:

          ...
          5:2345:respawn:/sbin/mingetty tty5
          6:2345:respawn:/sbin/mingetty tty6
          7:2345:respawn:/sbin/getty ttyS0

  4. Allow root to log into the console. To do this, add a "ttyS0" line to
     /etc/securetty:

          tty1
          tty2
          tty3
          tty4
          tty5
          tty6
          tty7
          tty8
          ttyS0

That's all there is to it. One other thing you might note is that you can
also add the other serial port to securetty and run a getty on it. It might
make life a little easier if your chosen serial port goes on the fritz, and
there's probably no compelling reason not to.

[snip]
-=-=-=-=-=-=

What I have tried, and Problems:
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

The key problem here is when the kernel starts uncompressing, data does
not come to screen until boot-up is done. the minicom session of the
connecting computer computer does not see any data come across

I had to modify the inittab time and appended "DT9600 vt100" to the end of
the line, as well as "F9600 vt100". Also changed a few other things per
the HOWTOs. In /etc/lilo.conf, added "serial = 0,9600n8" 

The problem in each case is at boot up and when the kernel is
uncompressing, no diagnostic information comes up, and its assumed it is
going though the serial, but nothing is seen on the console (a minicom
session from another linux box). 

I verified that the setup on the other linux box was ok, by connecting to
a console of a sun. That works fine. I also tested ot make sure that the
serial port is working on the linux box I want to be a serial console, by
using that serial port to connect to the console of a sun box, using
minicom on /dev/ttyS0. that works as well. 

My analysis from the results of my attmepts so far is that the hardware
being used fine, and the /etc/inittab is not the problem (at least not
yet) because that is simply for login sessions, and the diaganostic info
at bootup should be going see over the serial connection. The only thing
that remains is that I have /etc/lilo.conf set up wrong, or am missing
something


Can any give me any tips? 



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