Hello, It seems that Robert's email didn't reach the archives. I'm forwarding it below.
2015-03-12 5:13 GMT+01:00 Robert Ancell <[email protected]>: > Note I have removed the systemd-devel list from this so we're not > cross-posting. I think the XDG list is the right place to discuss this > though of course the input of the systemd developers would be very > useful. > > As the LightDM maintainer I support any moves to get a common API across DMs. > > As pointed out, logind has an effective API that has some duplication > with the current org.freedesktop.DisplayManager API. So I think if we > want to make a common API we should simplify what we currently have. > In particular I'd drop the Session / Seat object in > org.freedesktop.DisplayManager and rely on using the > org.freedesktop.login1 versions instead. For systems that don't use > logind you would be limited to single seat for the display manager. > > The main cases that I have seen which aren't currently provided by logind are: > 1. Switching to the login screen to choose a new session > 2. Switching to a guest / temporary account > > I think 1. has to be performed by the Display Manager since logind has > no method of forwarding that request easily unless it gains the > concept of a special "greeter" session. > 2. would be nice if it was handled by logind but this would take quite > some work. > > The minimal API that comes to mind is: > Boolean org.freedesktop.DisplayManager1.CanSwitchToGuest > org.freedesktop.DisplayManager1.SwitchToGreeter(Object Path seat_id) > org.freedesktop.DisplayManager1.SwitchToGuest(Object Path seat_id, > String session-name) > > I think we're OK in the Wayland/Mir/post-X world as none of these APIs > should have any detail at this level. We may have issues should > someone want to make a Display Manager with radically different > behaviour but I think that can be resolved should that ever occur. > > --Robert > > On Wed, Mar 11, 2015 at 2:40 AM, Mathieu Parent <[email protected]> wrote: >> (Note 1: please CC me) >> (Note 2: I have CC-ed two contacts from gnome-shell, one from gdm, one >> from lightdm, and the system-logind ML) >> >> Hello, >> >> There are currently several ways to ask the DM to switch to the login screen: >> - gdm3 uses org.gnome.DisplayManager.LocalDisplayFactory >> CreateTransientDisplay >> - lightdm uses org.freedesktop.DisplayManager SwitchToGreeter >> - old gdm, and kdm seems to use a socket without DBus >> - ... >> >> I am not involved in those projects, but I recently needed to switch >> to LightDM to have guest sessions, while keeping gnome-shell >> ([debian-guest-sessions]). gnome-shell send a CreateTransientDisplay >> when "Switch user", without any effect. >> >> I proposed a patch to gnome-shell [gnome-shell-SwitchToGreeter], which >> currently waiting for an implementation in gdm [gdm-SwitchToGreeter] >> and a written specification. >> >> This mail is to start a discussion about this DisplayManager specification. >> >> The current DBus interfaces used by lightDM seems to be a good staring >> point [lightDM-API], but some of its API may overlap with logind. >> >> Also, how can this work in the Wayland world? >> >> What is the way forward to have the same API in all DM? >> >> Refs: >> [debian-guest-sessions]: >> http://anonscm.debian.org/cgit/users/sathieu/guest-sessions.git/tree/ >> [gnome-shell-SwitchToGreeter]: >> https://bugzilla.gnome.org/show_bug.cgi?id=745940 >> [gdm-SwitchToGreeter]: https://bugzilla.gnome.org/show_bug.cgi?id=745938 >> [lightDM-API]: >> http://bazaar.launchpad.net/~ubuntu-branches/ubuntu/vivid/lightdm/vivid/view/head:/src/lightdm.c#L784 >> >> Regards >> >> -- >> Mathieu Parent _______________________________________________ xdg mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/xdg
