Unity on Wayland

The next major transition for Unity will be to deliver it on Wayland, the OpenGL-based display management system. We’d like to embrace Wayland early, as much of the work we’re doing on uTouch and other input systems will be relevant for Wayland and it’s an area we can make a useful contribution to the project.

We’re confident we’ll be able to retain the ability to run X applications in a compatibility mode, so this is not a transition that needs to reset the world of desktop free software. Nor is it a transition everyone needs to make at the same time: for the same reason we’ll keep investing in the 2D experience on Ubuntu despite also believing that Unity, with all it’s GL dependencies, is the best interface for the desktop. We’ll help GNOME and KDE with the transition, there’s no reason for them not to be there on day one either.

Timeframes are difficult. I’m sure we could deliver *something* in six months, but I think a year is more realistic for the first images that will be widely useful in our community. I’d love to be proven conservative on that :-) but I suspect it’s more likely to err the other way. It might take four or more years to really move the ecosystem. Progress on Wayland itself is sufficient for me to be confident that no other initiative could outrun it, especially if we deliver things like Unity and uTouch with it. And also if we make an early public statement in support of the project. Which this is!

In coming to this view, several scenarios were considered.

One is the continued improvement of X, which is a more vibrant project these days than it once was. X will be around a long time, hence the importance of our confidence levels on the idea of a compatibility environment. But we don’t believe X is setup to deliver the user experience we want, with super-smooth graphics and effects. I understand that it’s *possible* to get amazing results with X, but it’s extremely hard, and isn’t going to get easier. Some of the core goals of X make it harder to achieve these user experiences on X than on native GL, we’re choosing to prioritize the quality of experience over those original values, like network transparency.

We considered the Android compositing environment. It’s great for Android, but we felt it would be more difficult to bring the whole free software stack along with us if we pursued that direction.

We considered and spoke with several proprietary options, on the basis that they might be persuaded to open source their work for a new push, and we evaluated the cost of building a new display manager, informed by the lessons learned in Wayland. We came to the conclusion that any such effort would only create a hard split in the world which wasn’t worth the cost of having done it. There are issues with Wayland, but they seem to be solveable, we’d rather be part of solving them than chasing a better alternative. So Wayland it is.

In general, this will all be fine – actually *great* – for folks who have good open source drivers for their graphics hardware. Wayland depends on things they are all moving to support: kernel modesetting, gem buffers and so on. The requirement of EGL is new but consistent with industry standards from Khronos – both GLES and GL will be supported. We’d like to hear from vendors for whom this would be problematic, but hope it provides yet another (and perhaps definitive) motive to move to open source drivers for all Linux work.

Originally posted by Mark Shuttleworth here on Thursday, November 4th, 2010 at 9:16 pm

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