Re: GDM future work

[Ludovic Courtès]

Hi Timothy!

Timothy Sample <address@hidden> skribis:

> I have been using GDM on GuixSD for the past few days, and I am quite
> happy with it.  A few patches that make it usable just landed on
> master.

Nice!

> The main issue is the way that GDM launches the session bus (the
> instance of D-Bus that manages the session).  It launches it from a
> clean environment that has little more than what PAM gives from
> “/etc/environment” (and “~/.pam_environment”, if it exists).  The result
> is that D-Bus can’t find any services, because it doesn’t have
> “XDG_DATA_DIRS” set.
>
> Currently, this is solved by patching GDM to thread “XDG_DATA_DIRS” into
> the process the launches D-Bus, but that’s not great.  There are at
> least two better options.
>
> (1) Extend the PAM environment service so that it puts important
> environment variables for D-Bus in “/etc/environment”.  This is easy to
> do, and fits pretty naturally with the way that GDM works.
>
> (2) Set up a wrapper script for D-Bus like the wrapper script we
> currently use for X.  This way, we could very precisely set up where the
> session bus looks for system and user service files.  This seems to be
> more like “the Guix way”, but it would mean threading a
> “GDM_DBUS_LAUNCH” environment variable through the GDM code (like we
> currently do with “GDM_X_SERVER”).

Option #2 looks reasonable to me (for the reasons you wrote, “static
binding” and all.)

> Besides these two options, I get tempted to think even bigger.  We could
> replace a lot of the GDM session initialization code with our own code,
> and then if we only had per-session Shepherd instances….  That’s
> probably too big for right now.  :)

Heh, sounds tempting… once 1.0 is out!  :-)

> Besides this, there are few straight-forward things to do.  We need to
> make a “libgdm” package that does not depend on “gnome-shell” [1].  It
> would be nice to fill out the config record and get rid of the opaque
> configuration text file.  We need documentation for GDM in the manual.
> Finally, I already miss the Guix logo from SLiM, so even if it is not
> the default, I would like a Guix theme to be available.  :)
>
> I will chip away at these as I have time, but of course anyone is
> welcome to jump on them if I’m too slow.

Cool, I’d be happy to test it, let us know when you’d like to get test
feedback!

Thanks for working on it!

Ludo’.