If you missed the other Phoronix coverage about Mir up to this point, see:
- Ubuntu's Unity Written In Qt/QML For "Unity Next"
- Upstream X/Wayland Developers Bash Canonical, Mir
- The Developers Behind The Mir Display Server
- Building & Running The Ubuntu Mir Display Server
- A Note To Canonical: "Don't Piss On Wayland"
With Canonical not basing Mir on Wayland or X.Org that have existing Mesa back-ends, they needed to write their own EGL/DRI2 back-end. Christopher James Halse Rogers posted the initial back-end to the mesa-dev list on Tuesday morning. "A first pass at a Mir platform for EGL. This is RFC mainly because I hope to shortly make Mir's API less painfully pointless-callback-based. There's no point in committing this as-is, but it's hopefully still useful to review."
Up to this point the Mir back-end was developed in private and then it was found in a patched version of Mesa from a Launchpad PPA. As said by Roger's patch mailing list message, he's mostly seeking comments from the upstream Mesa developers on the back-end -- many of whom are the same developers that were already so riled up yesterday by Canonical abandoning Wayland for Ubuntu. So he's not for pushing it into Git straightaway but is wanting comments and also to clean up their clumsy/"painful" Mir interface.
As said in the earlier Phoronix posts about Mir, at the moment this display server is just working with the open-source Radeon and Intel drivers but not Nouveau. Canonical also hopes to make Mir compatible with the proprietary Android graphics drivers too. They also carry the ambitious hope that NVIDIA and AMD will provide the necessary EGL interfaces for supporting Mir as well.
This Mir Mesa back-end is needed to render things like their current display server demo, as built yesterday on Phoronix:
So far no upstream developers have commented on this rare Mesa patch by Canonical.