lightdm or gdm?

[Tim]

On 20/04/17 00:32, Sebastien Bacher wrote:
> - gnome-shell uses gdm for its lockscreen so work is needed to make it
> work with lightdm
That is not entirely right, the GUI for gdm is actually a cut-down 
gnome-shell session, this applies to both lock screen and greeter. gdm 
does however handle all user authentication, which is a little different 
from how lightdm work afaict (Robert correct me on this If I am wrong).

When we started Ubuntu GNOME, gdm was problematic on Ubuntu, I spent 
alot time working with halfline (ray) to iron out the issues and 
everything is upstream. These days its pretty stable and works perfectly 
in most cases. Although lightdm does seem to handle better the corner 
cases where openGL config is broken for whatever reason.

I probably don't know enough about lightdm code to make a proper 
comparison, but if you have lightdm running the gnome-shell greeter, and 
replicating the auth channels and user switching interfaces to make it 
compatilbe with gnome shell (without patches). What technical reasons 
remain ? So far as I can tell its really only the tests?