D18570: EGLStream DRM Backend Initial Implementation

ekurzinger added inline comments.

INLINE COMMENTS

> graesslin wrote in CMakeLists.txt:29
> Why are these two libraries needed?

wayland-server is needed in order to register the wl_eglstream_controller interface. The NVIDIA driver uses this when an application creates a native EGL window to pass the corresponding EGLStream to the compositor

dl is needed because we dynamically load libnvidia-egl-wayland.so since that library would only be present on systems with the NVIDIA driver installed, so we would only want to require it if using the EGLStream backend.

> graesslin wrote in drm_backend.cpp:751
> Wouldn't it make more sense to try the available backends? E.g first create EglGbmBackend, if that fails create EglStreamBackend - comparable to how we load the compositor.

If Mesa is available, creating an EglGbmBackend should always succeed, I believe. On systems running the NVIDIA driver it will just fall back to using llvmpipe-based software rendering (of course, with abysmal performance).

We could attempt to create the EglStreamBackend first, which should fail on any non-NVIDIA systems, and then fall back to GBM (and then QPainter). Alternatively, I suppose we would need some way to detect if the NVIDIA driver is present. There are probably a few ways to do this but they might be a little hacky.

And re: zzag I can totally make the EGLStream stuff compile-time optional if that would be preferred, I'll work on an amended version of the change and get it up shortly.

REPOSITORY
  R108 KWin

REVISION DETAIL
  https://phabricator.kde.org/D18570

To: ekurzinger, romangeints, davidedmundson, graesslin, #kwin, romangg
Cc: romangg, hein, nicolasfella, zzag, kwin, jraleigh, GB_2, mkulinski, ragreen, jackyalcine, Pitel, iodelay, bwowk, ZrenBot, ngraham, alexeymin, lesliezhai, ali-mohamed, hardening, jensreuterberg, abetts, sebas, apol, mart