ubuntu-multiseat team mailing list archive

[Richard Hansen <ubuntu-a7x@xxxxxxxxxxxxxxx>]

On 2013-08-24 06:08, Laércio Benedito Sivali de Sousa wrote:
> Hi guys!
> 
> Just a comment about deriving or not the seat id from [Seat:Foo] header.
> I still really appreciate if I can have an option for this. For example,
> if I set "xdg-seat=auto" (no problem here since "auto" is not a valid
> seat id anyway)

AFAIK, there's nothing limiting the set of valid seat names, so 'auto'
is a valid seat name.  It's a bad idea to use 'auto' as a seat name due
to the potential for udev tag conflicts, though, so hijacking it to have
a special meaning in lightdm.conf is probably OK.

> or something similar, then derive seat id from section
> header.

Interesting idea, but I'm hesitant to implement it myself because I
suspect automatic multiseat support will largely make this an unused
feature.  When automatic multiseat support is implemented, rather than this:

    [SeatDefaults]
    greeter-session=unity-greeter
    xdg-seat=auto

    [Seat:0]

    [Seat:1]

people will simply do something like this:

    [SeatDefaults]
    greeter-session=unity-greeter

    [AutoSeats]

and seat0 and seat1 will be used automatically as they are reported by
logind.  Until automatic multiseat is implemented, it's not too
obnoxious to require users to do this:

    [SeatDefaults]
    greeter-session=unity-greeter

    [Seat:0]

    [Seat:1]
    xdg-seat=seat1

I don't expect it will take very long to implement automatic multiseat,
so this would only be a brief inconvenience.

> I have two alternatives for this:
> 
> - [Seat:Foo] should expand to seat id "seatFoo", provided that
> lightdm.conf can accept section headers like [Seat:-Foo], because some
> autoseat devices (like Plugable ones) receive an automatic seat id of
> kind "seat-XXXX", where XXXX is calculated by udev.
> 
> - [Seat:Foo] should expand to seat id "seat-Foo". In this case, [Seat:0]
> would expand to a secondary seat named seat-0, which is different from
> primary seat seat0. In this case, we should have a special section
> [Seat0] or similar for seat0 settings.

[Seat:Foo] -> seatFoo (the former) is my preferred option.

If Robert isn't opposed to this xdg-seat=auto idea, and you feel like
coding it up, feel free to push it to the
lp:~ubuntu-multiseat/lightdm/multiseat branch.  Note that you'll have to
sign Canonical's contributor agreement
<http://www.canonical.com/contributors>, which is not very
developer-friendly (see
<http://ebb.org/bkuhn/blog/2011/07/07/harmony-harmful.html>).

-Richard