Bug#770404: systemd: breaks lightdm, does not start anymore

[Sjoerd Simons]

reassign 770404 lxdm
thanks

On Fri, Nov 21, 2014 at 08:01:50PM +0000, Simon McVittie wrote:
> This looks wrong. I think it might be caused by this in lxdm.service:
> 
>     [Install]
>     Alias=display-manager.service
> 
> Neither gdm3 nor lightdm have that, which suggests that it isn't
> meant to be necessary.
> 
> I think what's happening is that when you install lxdm, that Alias directive
> causes the debhelper snippets in its postinst[1] to break the mechanism
> that is meant to arbitrate who owns display-manager.service: the part of
> its postinst headed "# set default-display-manager systemd service link"
> is correct, but then the #DEBHELPER# snippet runs "systemctl enable lxdm"
> which sees the Alias, obeys it, and overwrites the display-manager.service
> symlink with an incorrect target.

Correct, that Alias= breaks our current mechanism for arbitrating the DM to use
(that is, the sylink and the config file go out of sync).

See also Martin pitt's comment for lightdm way back when:
  https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=733220#25

> systemd maintainers: do you agree with my reasoning, and that that
> bit of lxdm.service is wrong? If so, please reassign this to lxdm
> (which is conveniently not a blocker for jessie, since it is only
> in unstable).

reassigning :)

-- 
All men know the utility of useful things;
but they do not know the utility of futility.
		-- Chuang-tzu