Hi On Thu, Dec 10, 2015 at 2:28 PM, Martin Peres <martin.peres at linux.intel.com> wrote: > Yes, you are right, it will require changes for the non-X case. > > Since you spent a lot of time on it, could you share with us some of the > issues you found? We still think that using the DRM interface may be more > work, but at least it would improve the state of the graphics stack.
The biggest issue is that most compositors are built around the assumption that one/_the_ DRM card is always accessible and usable. That is, they hard-code a fixed path to /dev/dri/cardX and use it. They cannot deal with hotplugging of DRM cards, they cannot deal with no card being present and they cannot rate cards and evaluate whether a card is something they want to use or not. That infrastructure is just not available in any compositor I have seen, and it is non-trivial to write. Apart from that, the biggest problem I see is that multi-GPU systems are usually non-standard. You *have* to know the exact setup beforehand to make it work properly. It is hard to write a heuristic that properly detects which cards should be used in what way. Thanks David