Review Request 112294: Implement multi-seat support in KDM

Oswald Buddenhagen ossi at kde.org
Mon Jun 2 07:32:37 BST 2014



> On May 31, 2014, 9:35 a.m., Oswald Buddenhagen wrote:
> > kdm/backend/dm.c, line 1463
> > <https://git.reviewboard.kde.org/r/112294/diff/8/?file=276202#file276202line1463>
> >
> >     this is actually tricky ... what if the display is still there but the seat changed? i don't think you are handling the transition (which would involve the 'raiser' state, iirc), so the display would come up again only after the next hup or replug.
> >     
> >     it's probably not worth it to handle the complexity, but maybe add a comment somewhere.
> 
> Stefan Brüns wrote:
>     Can you please elaborate? As long as a seat is running it is fixed to a seat. Changes to the class specifier for a running display are not handled, but that has always been the case.
> 
> Oswald Buddenhagen wrote:
>     hmm, right.
>     
>     note that this is semantically a bit different than changing the class, because it isn't just a minor config parameter. anyway, not worth the trouble to handle it differently.
> 
> Stefan Brüns wrote:
>     This could be done by not using the class attribute, i.e. use @seat-foo:0 instead of :0_ at seat-foo. @seat-foo:0 would be the name, and the lookup happens by name. On the other hand, the server startup code would have to handle stripping the seat name before starting a local display.
>     
>     On the other hand <hostname>:<diplaynumber> has a fixed meaning in the X world, and using a @seat-foo hostname would break X semantics. So I prefer sticking with the class name for the seat.
>     
>     Issue fixed?

well, i elaborated on the pros and cons of that approach already ...
i don't really buy into "break X semantics". one could say the same about overloading the class. it's not visible outside kdm, so it doesn't matter.

anyway, as i said, it's not worth the trouble, so close it unless you feel the urge to make it more elegant despite zero practical gain.


- Oswald


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On May 29, 2014, 7:03 p.m., Stefan Brüns wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://git.reviewboard.kde.org/r/112294/
> -----------------------------------------------------------
> 
> (Updated May 29, 2014, 7:03 p.m.)
> 
> 
> Review request for kde-workspace and Oswald Buddenhagen.
> 
> 
> Repository: kde-workspace
> 
> 
> Description
> -------
> 
> This patch implements dynamic multiseat in KDM. It follows the description in:
> http://www.freedesktop.org/wiki/Software/systemd/writing-display-managers/
> 
> In case systemd is no found at compile time, nothing changes. If logind is not running, nothing changes. If no additional seats have been configured (some Plugable USB-GPUs are automatically added as additional seats), nothing changes.
> 
> In case there are additional seats beyond seat0, a reserved display is promoted to a local static one (and demoted if the seat is removed) and a new X-Server/greeter is spawned.
> 
> The code has been tested extensively, with a combination of [Radeon dedicated GPU|Intel iGPU], [Intel iGPU|Displaylink USB GPU] and others. For history of this patch, see https://bugzilla.redhat.com/show_bug.cgi?id=884271 and https://bugzilla.redhat.com/show_bug.cgi?id=975079
> 
> 
> Diffs
> -----
> 
>   cmake/modules/CMakeLists.txt 117b3a5 
>   kdm/ConfigureChecks.cmake b61fd90 
>   kdm/backend/CMakeLists.txt 25f383f 
>   kdm/backend/client.c a2d06c2 
>   kdm/backend/dm.h b2f8c61 
>   kdm/backend/dm.c 77a2ef7 
>   kdm/backend/dpylist.c b650c2f 
>   kdm/backend/resource.c 38a8c70 
>   kdm/backend/server.c d8dd6f3 
>   kdm/config-kdm.h.cmake 3e8912d 
>   kdm/kfrontend/kdm_config.c 368c8d1 
> 
> Diff: https://git.reviewboard.kde.org/r/112294/diff/
> 
> 
> Testing
> -------
> 
> Single seat system, several multiseat systems
> 
> 
> Thanks,
> 
> Stefan Brüns
> 
>

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