Not entirely. I had planned (except that I needed this to run on X for the thing I was doing locally) to pass EGL window surfaces. It would still include a copy, but it's between textures on the card, not being read back into main memory which is the slow part. Sharing a GBM won't work on all platforms, and you'll never be able to do partial screen capture on the kwin side.

But if something's in progress. Cool.