I now have a setup with 2 GPUs and want to try to make the reference wayland compositor weston to work on 2 GPUs. Weston currently only supports single kms devices with one or more outputs. Add support to Weston's DRM backend to open several KMS devices, with the ability to use outputs from all of them.
The project is a gsoc xorg idea in: https://www.x.org/wiki/SummerOfCodeIdeas/
Skills/software to learn: - libdrm - wayland protocol
This project is one of its kind!