Re: [uml-user] serial lines between uml instances

[<jd...@gm...>]

Hi,

> > I try to setup a kind of rescue console for a few users of mine. As Jeff
> described in the howto and in his book, there should be a simple setup of
> connecting to uml instances with each other.
> >
> > master_uml -> slave_uml
 
> Can you describe exactly what you're doing, and exactly how it doesn't
> work?

Sure, sorry for not describing everything I did - I tried for such a long time, that I don't remember all the things I tried.

Generally, I follow the steps in your book, I've got two UML instances, master_uml and slave_uml. master_uml shall service the poor soul that killed his ssh on its primary instance, the slave_uml. What I want to do is give this person a login into the master_uml which, after authentification on this servicing master_uml, leads him to the auth of his, broken, slave_uml.

My setup consists of two instances on a local network, both instances run on 2.6.18.1 kernels with a quite lean inittab, the console part looking as follows:

# UML console start:
0:1235:respawn:/sbin/getty 38400 tty0 linux

My normal startup cmdline looks like

con=pts con0=fd:0,fd:1

That kind of works for starting the instance up in a screen and gives me the possibility to login via screen or via network/ssh.

Now I try to interconnect the two instances according to your book's chapter 'A Virtual Serial Line' - but I don't really get the clue I think, sorry :-(

First of all, I set up a pts on con 8:

host: uml_mconsole master_uml config con8=pts
OK

Now I start a getty in the instance:

master_uml: /sbin/getty 38400 tty8

which results in:

get_pty : Couldn't grant pty - errno = -2
open_pts : Failed to open pts
Registering fd 0 twice
Irqs : 2, 2
Ids : 0x0864e4c4, 0x0864e218

Debian GNU/Linux 4.0 master_uml tty8

master_uml login:

This login is not usable, one can only ctrl-c out of there.

If I keep it running and follow the instructions furthermore, I try to take a look on the host about which pts the con8 got assigned to:

host: uml_mconsole master_uml config con8
OK pts

There's no pts:/dev/pts/28 or any other number, just the 'OK pts' which fits to the error from above, I guess.

The next steps:

host: uml_mconsole slave_uml config con8=tty:/dev/pts/<number>

and

slave_uml: screen /dev/tty8

seems useless at this point, because of the missing pts number.

My main problem seems to be, that I don't find a way to configure inittab for

- access via screen on startup
- access via network whilst running
(which both works great until I try to interconnect the two instances via serial line)

- access one uml via serial line from the other instance.


What I need is a hint about

/etc/inittab

What to configure there to enable the serial stuff and a screen login

and about

the uml cmdline

I tried several things from ssl1=pts to unnumbered other attempts, but I don't get it, sorry :-(

I would be very grateful for any pointer to my personal point of failure in this subject. I do remember that I once had an interconnection between two umls, but I did not document what was different from my actual setup and it's been quite a while since then. Frustrating :-(

Kind regards,
Karl
-- 
"Ein Herz für Kinder" - Ihre Spende hilft! Aktion: www.deutschlandsegelt.de
Unser Dankeschön: Ihr Name auf dem Segel der 1. deutschen America's Cup-Yacht!