[LightDM] lightdm at lists.freedesktop.org

Robert Ancell robert.ancell at gmail.com
Sun Aug 21 17:03:27 PDT 2011

On 19 August 2011 00:52, PCMan <pcman.tw at gmail.com> wrote:
> I just migrated my own GtkBuilder-based greeter to LightDM 0.9.x. However, I
> found that language selection is no longer available. We relied on this
> feature in the previous version. The feature is also supported by gdm and
> lxdm. With LightDM 0.9 supporting this is not possible. I read the source
> code and found that "Language" value in .dmrc is not used. So there is no
> way to configure language for the selected session.
> In NEWS file of lightdm, I noted that this is deliberately removed and users
> should set locale in .profile. However, .profile is not always loaded
> depending on the distro/environment used. Moreover, this requires that users
> edit config files manually. Is it possible to restore this feature in
> LightDM or at least give us other ways to do it?
> If LightDM is not going to support this, will LightDMLanguage be removed
> later? If Language defined in .dmrc is not reference by lightdm, will
> lightdm_user_get_language be removed?
> Besides, I found a bug in LightDMUser. Every call to lightdm_user_get_*
> loads dmrc again and causes memory leaks. Please check this part. Thanks.

lightdm_user_get_language is not going to be removed, as it is useful
even if you can't set the language for a user.  For example selecting
a user should change the greeter to their language.  LightDMLanguage
will not be removed as it would break API.

The easiest way to set the locale is to set it in the session wrapper
(session-wrapper in lightdm.conf).  If you want to grep the .dmrc and
use that then that would work, but I'd recommend you load ~/.profile
and have that set by your locale configuration tool.

Language is a messy problem (as shown by the endless problems we have
had in Ubuntu trying to get it working reliably)

Problem #1 is language != locale.  If the greeter can only choose
language it can't configure all the detail required to set up a
locale.  If you were to make it support everything it would be too
complex.  If you allow the greeter to set arbitrary environment then
that ignores the problem and makes it inconsistent between different

Problem #2 is locale is not just for GUIs.  It really should be
external to the display manager and applied to all logins.  It really
shouldn't be in the .dmrc.

Problem #3 is who is responsible for setting the locale environment
variables?  The environment is set up like this:
- LightDM sets a default environment
- PAM sets more environment
- LightDM sets some GUI specific variables, e.g. XAUTHORITY XDG_SEAT_PATH, ...
- Environment is set in the session script (session-wrapper config
value in lightdm.conf, or /etc/gdm/Xsession in GDM).

Ideally LightDM wouldn't set have to do the default and it would all
come from PAM.  The locale should come from PAM or from the session
script if that isn't possible.

Thanks for the tip on the memory leak.

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