This change is a prerequisite for multi-GPU support.
Overall, the desired design:
- there are multiple DrmDevice devices;
- all DrmDevice devices form master-slave relationship, where master
device, aka primary device, is used for all rendering and exporting
- Each DRM object is associated with one particular DRM device.
In general it would be nice to refactor rendering infrastructure in
kwin, perhaps we need several "renderers." One that is used for rendering
the scene, and the other one is used to render cursors (animated cursors
The DrmDevice class is currently a no-op. I submitted this change just
to let you know what I'm working on.