Bug#1025349: gdm3: should define the display-manager alias for start dependencies

[Samuel Thibault]

Simon McVittie, le lun. 05 déc. 2022 00:15:01 +0000, a ecrit:
> Upstream gdm3.service (or possibly gdm.service, I think we do some renaming
> for historical reasons) has
> 
>     [Install]
>     Alias=display-manager.service
> 
> so that `systemctl enable gdm3.service` will create a symlink
> /etc/systemd/system/display-manager.service -> /lib/systemd/system/gdm3.service.
> This assumes that only one display manager can be enabled at a time, and
> preferably only one *installed* at a time: if both gdm3 and lightdm try
> to do that, if I understand correctly, the result will be unpredictable.
> 
> In Debian, instead of gdm3.service having that, the debconf question
> creates that symlink programmatically if and only if gdm3 is the selected
> display manager (in particular, the symlink isn't created if you have
> installed both gdm3 and lightdm, and chosen to use lightdm instead).
> 
> If I understand correctly, any mechanism that makes the symlink exist
> should be enough for "Before=display-manager.service" to do what you want
> it to do. Please try it?

Ah, indeed, that works, sorry for not having actually tried, because
lightdm does have these two lines. But then, with this reasoning,
lightdm is bogus by having these two lines?

Samuel

> systemd maintainers: Am I getting this right?
> 
>     smcv
>