lightdm or gdm?

Robert Ancell robert.ancell at
Wed Jun 7 09:02:24 UTC 2017

Hi all,

Where we are today:
- GDM is undergoing a security check to be included in main [1].
- We've got GNOME Shell onto the 17.10 image, running under LightDM.
- We've attempted to get the GNOME Shell lock screen running with LightDM
and using GNOME Shell as a LightDM Greeter. Which this still seems
possible, it's not easy to patch GNOME Shell as the GDM code is hard to
- Other tasks have left not much time to work on GNOME Shell / LightDM

When we started investigating LightDM with GNOME Shell we wanted to
re-assess after about a month and see if it was still worth continuing
with. That time is now.

Given the workload we have and the risks in modifying GNOME the decision is
to use GDM for 17.10 and thus 18.04 LTS.

Where this leaves LightDM:
- We continue to support LightDM for the supported Ubuntu releases.
- We will support LightDM for use in the other flavours, though this is
likely to be limited to bug fixes from the Ubuntu desktop team.
- Others are still welcome to contribute to LightDM.



On Thu, Apr 20, 2017 at 2:32 AM Sebastien Bacher <seb128 at> wrote:

> Hey there,
> That's a topic that was mentioned during the meeting yesterday and
> something we need to decide on early in the cycle since there is going
> to be work needed on that front to have a fully working session.
> I'm doing a small summary of what I think are the pro (+) and con (-) of
> each
> * lightdm
> + well tested in Ubuntu
> + we have people in the team knowing the codebase
> + shared with other flavors/greeters selection
> + guest session
> - divergence from upstream
> - we are the maintainers so it's more work for us
> - gnome-shell uses gdm for its lockscreen so work is needed to make it
> work with lightdm
> * gdm
> + that's the GNOME solution, works today with wayland & gnome-shell
> - we started lightdm because we found the gdm codebase not easy to work
> on, that might still be true
> - ?keeps an active session from the greeter even after logging which
> uses resources? (it was mentioned on IRC, to be confirmed, is that
> needed due to the lockscreen?)
> - no guest session, we need to work on that or decide to drop the
> feature from Ubuntu
> I talked a bit with Robert yesterday who said he could make lightdm use
> the gdm greeter (he has some work started on that a few cycles ago)
> which means it could be used as GNOME lockscreen instead of gdm. He's
> probably the best placed to comment on the work and pro/con of the
> solutions though so I'm going to let him go into the details when he
> replies.
> Cheers,
> Sebastien Bacher
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