Re: [gdm-list] Multi-seat with multiple X-servers

[Brian Cameron <Brian Cameron Sun COM>]

Paul:

> I have one server with 2 displays, 2 keyboards, 2 mice.
> And I would like to build other ones, with more then 2 "seats".
>
> It is not a terminal-server-like environment, every display hangs with a
> cable directly at the server.
>
> Maybe look here to get an idea:
> http://en.wikipedia.org/wiki/Multiseat_configuration

Whether the displays are connected directly to the server or via some
other mechanism typically doesn't matter to GDM.  From GDM's perspective
these two use cases are similar.  Obviously, from an Xorg configuration
standpoint, they are quite different.

> > What version of gdm are you using?  You can run
> > "gdmflexiserver --version" or "gdmflexiserver --command=VERSION" to find
> > out if you are not sure.
>
> GDM 2.20.7

That explains why it works.

> > > My multi-seat configuration is now completely in xorg.conf, I don't need
> > > any setting in gdm.conf anymore.
> > >
> > > Because of that I don't expect any problems with the new GDM, or am I
> > > wrong?
> >
> > I think it depends on what sort of behavior you expect from GDM, and
> > what version of GDM you are using.  GDM 2.20 and earlier have good
> > support for MultiSeat, while GDM 2.21 and later are only able to
> > manage a single local display (and additional XDMCP displays).
>
> That sounds as a problem for me.

Yes, it would be.

> > If you are using Xinerama or some other Xorg configuration to make
> > multiple monitors seems like a single display to GDM, then it should
> > "just work".  In other words, I think both the old and new GDM support
> > MultiDisplay reasonably well.
>
> It's not multidisplay, it's multiseat. With on this machine 2 videocards
> and 2 X-servers.

Right.

> > However, if you are using the new GDM and expecting GDM to separately
> > manage each display in a MultiSeat fashion, then I do not think that
> > is possible with the new GDM.  If you have found some trick to make
> > the new GDM work with MultiSeat via only configuring xorg.conf, then I,
> > for one, would be interested to hear how you got this working.
>
> I am using the old one, and I would like to know if I get problems with
> the new one... I will add my xorg.conf as an attachment.

I'd think you would have problems, yes.  The new GDM does not support
MultiSeat yet.

> > If you are applying the ConsoleKit and GDM patches as mentioned
> > in bugs.freedesktop.org bug #19333 and bugzilla.gnome.org bug #536355,
> > then this does add MultiSeat support and should allow you to configure
> > GDM to work in this way.  However, this is bleeding edge code, and may
> > have bugs and the configuration interfaces may not be fully stable yet.
>
> I saw it, and I would like to know if I need it. And if it would work
> for me.

Probably not, unless you build the new GDM with the patches I pointed to
in my previous email.  Hopefully these patches will get into the new GDM
in the 2.30 timeframe, and then it should work for you.  We were hoping
to get this work done in the 2.28 timeframe, but it ended up being much
more work than we expected.

Brian