Implementing Miracast?

[David Herrmann]

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