Re: New module proposal: LightDM

[Robert Ancell <robert ancell gmail com>]

On 13 May 2011 16:01, Matthew Garrett <mjg59 srcf ucam org> wrote:
> On Fri, May 13, 2011 at 02:59:06PM +0200, Robert Ancell wrote:
>
>> - I am confident that the LightDM architecture is simpler than GDM.
>> Some indicators of this:
>>   - Smaller code size
>>   - Well defined interface between greeter and session
>>   - Less dependencies
>>   - Less internal interfaces
>
> The daemon side of LightDM (including the gobject bindings) is about
> 10,000 lines of code, which compares to 35,000 lines in gdm. Are they
> feature comparable? Does LightDM currently implement the same user
> switching interface?

It has a different user switcher interface, but backwards
compatibility is something I am looking into (as well as defining a
XDG standard for display manager interfaces).

> Practically speaking, in order to avoid feature regression the obvious
> way to use LightDM would be to port the existing gdm greeter to the
> LightDM backend. Who would be doing that work?

It certainly is an option.  I think the ideal solution would be to
make implement a clutter based greeter as designed for GNOME 3 [1].
While I will be working on LightDM for the next six months, I don't
feel I have the time to make this shine and someone would need to
volunteer for this work.

[1] https://live.gnome.org/GnomeShell/Design/Whiteboards/LoginScreen

>> - By having a well defined interface between the greeter and daemon,
>> it is significantly easier to develop a greeter without knowledge of
>> how display management works.  This is useful as the skillset and
>> motivations of these two sets of developers are different.
>
> This is a benefit, but I'm not sure it's a huge one. The platform in
> general hasn't been designed with "Make it easy for users to write new
> UI for existing applications" as a goal.

Sure, but I think the current solution has been held back by the
difficulty of doing this.  We will want to revamp the greeter/shell in
the future (or new technology might require it) and being able to do
that easily is useful.