Mir release 0.28

[reposted from https://community.ubuntu.com/t/mir-release-0-28/545 comments are enabled there, and disabled here]

Mir 0.28

We are pleased to announce that Mir 0.28 has been released and is available in Ubuntu 17.10 (Artful).

As the content (and even the name) of this release has changed over the time we’ve been working towards it now is probably a good time to reflect on what it is, and what it isn’t after all.

What is in Mir 0.28?

There is now a stable server ABI

This simplifies the use of “Mir snaps” making it possible to release new library versions without breaking servers.

One of the barriers to the adoption of Mir has been the potential for Mir releases to break downstream projects that depend on a stable ABI. This is provided by libmiral, which is now part of Mir.

The Yunit project which uses Mir as part of its graphics stack has already started migrating code to use libmiral for this reason.

The start of Wayland support

The desktop community has adopted Wayland as the client-server protocol of choice for replacing X11. This is already supported by several server implementations (Weston, Kwin and Mutter are the best known). By providing Wayland support we will make Mir servers compatible with the various toolkits and libraries that already have Wayland backends.

Our MVP goal for Mir 0.28 has been to support a Wayland client with a single fullscreen surface. We have slightly exceeded this goal in 0.28 as you can see from this short video:


We will continue to expand on this Wayland support in future releases.

The MirAL shells are part of Mir

The miral-kiosk shell is used by the mir-kiosk-snap to provide graphics support on UbuntuCore. This release includes a number of improvements to miral-kiosk based on feedback from potential users.

The miral-shell is now the canonical example of writing a Mir server. We’ve dropped several older examples that used other APIs (and reworked mir_demo_server to fit the new server APIs).

There is a (currently unstable) API for “graphics platform” plugins

We had planned to stabilize the graphics platform API and ABI before publishing it but we had to change that plan. Canonical no longer has the infrastructure to test and maintain the “android platform”. However there is was interest from UBports both in continuing to support the “android platform” and for developing a “Wayland platform”.

What is NOT in Mir 0.28?

We have not upstreamed Mesa distro patches

These patches support “Mir EGL” which forms part of the Mir client API. With the adoption of Wayland (and Wayland EGL) it looks likely that these will not have a long term future and upstreaming a wasted effort.

This should also become less of an issue as it only affects EGL clients using the legacy Mir client APIs. Software rendering, Xmir and Xwayland clients will work without these patches.

Custom compositing in Mir servers

Although Mir 1.0 hasn’t quite shipped yet my thoughts are turning to what we do next. One of the work items that got paused was removing the mirserver dependencies from QtMir.

While Canonical isn’t using QtMir, the purpose of the affected code is still relevant. It enables custom compositing for transitions and other effects and this is of continuing, wider, interest.

Clearly Qt isn’t the only framework that might want to customize the way the server composites the scene and Mir ought to support a range of options through a stable, well thought out API.

We need to start somewhere. A few conversations over the past few days have identified a couple of options: GDK4 and Clutter.

I don’t know enough yet to prioritise or plan this work, but input from anyone interested in helping get one of these toolkits working would be great.

Mir support for Wayland

I’ve seen some confusion about how Mir is supporting Wayland clients on the Phoronix forums . What we are doing is teaching the Mir server library to talk Wayland in addition to its original client-server protocol. That’s analogous to me learning to speak another language (such as Dutch).

This is not anything like XMir or XWayland. Those are both implementations of an X11 server as a client of a Mir or Wayland. (Xmir is a client of a Mir server or and XWayland is a client of a Wayland server.) They both introduce a third process that acts as a “translator” between the client and server.

The Wayland support is directly in the Mir server and doesn’t rely on a translator. Mir’s understanding of Wayland is going to start pretty limited (Like my Dutch). At present it understands enough “conversational Wayland” for a client to render content and for the server to composite it as a window. We need to teach it more “verbs” (e.g. to support for the majority of window management requests) but there is a limited range of things that do work.

Once Mir’s support for Wayland clients is on a par with the support for “native” Mir clients we will likely phase out support for the latter.

We’re still testing things prior to the Mir 1.0 release, and Mir 1.0 will not support “everything Wayland”. If you are curious you can install a preview of the current development version from the “Mir Staging” PPA.

Mir related ppas

Mir staging ppa

A few weeks ago I was reminded of the “Mir staging ppa” and saw that, with the discontinuation of Unity8 it had fallen into disuse. After considering deleting it I eventually removed some Ubuntu series that are no longer supported and added MirAL trunk.

That means that for Xenial, Zesty and Artful you can get the latest development version of Mir and MirAL like this:

sudo add-apt-repository ppa:mir-team/staging
sudo apt-get update
sudo apt-get upgrade

miral-release ppa

Now for the Internet of Things we are using UbuntuCore16 and snaps, but occasionally it is useful to have debs too. For Mir it is easy to use the underlying 16.04LTS (Xenial) archive, but MirAL isn’t in that archive.

To make up for that I’ve created a “miral-release” ppa containing the latest release of MirAL built for both Xenial and Zesty. Vis:

sudo add-apt-repository ppa:alan-griffiths/miral-release
sudo apt-get update
sudo apt-get upgrade


Mir release 0.27

Mir release 0.27/MirAL release 1.4

This is an interim development release of Mir and MirAL to Ubuntu 17.10 (Artful) that delivers many of the features that were work-in-progress when we needed to restructure the project. The Mir release notes are here: https://launchpad.net/mir/0.27/0.27.0.

The MirAL 1.4 release exposes a few new features and removes support for Mir versions that are no longer supported:

  • Support for passing messages to enable Drag & Drop
  • Support for client requested move
  • Port to the undeprecated Mir APIs
  • Added “–cursor-theme” option when configuring a cursor theme
  • Drop support for Mir versions before 0.26

There will be further Mir releases culminating in a Mir 1.0 release before the Ubuntu 17.10 (Artful) feature freeze in August.

Mir: the new order

The Past

The Mir project has always been about how best to develop a shell for the modern desktop. It was about addressing concerns like a security model for desktop environments; convergence (which has implications for app lifecycles); and, making efficient use of modern hardware. It has never been only about Unity8, that was just the first of (hopefully) many shells written using Mir. To that end, the Mir developers have tried to ensure that the code wasn’t too tightly coupled to Unity8 (e.g. by developing demo servers with alternative behaviors).

There have been many reasons that no other shells used Mir but to tackle some of them I started a “hobby project” (MirAL) last year. MirAL aimed to make it easier to build shells other than Unity8 with Mir, and one of the examples I produced, miral-kiosk, proved important to Canonical’s support for graphics for the “Internet of Things”. Even on the Internet of Things Mir is more than just a way of getting pixels onscreen, it also fits the security model needed. That secures a future for Mir at Canonical.

The Present

In Canonical the principle target for Mir is now Ubuntu Core, and that is currently based on the 16.04LTS. We’ve recently released Mir 0.26.3 to this series and will be upgrading it to Mir 1.0 when that comes out.

Outside Canonical there are other projects that are making use of Mir.

UBports is taking forward the work begun by Canonical to support phones and tablets. Their current stack is based on an old release of Mir (0.17) but they are migrating to Ubuntu 16.04LTS and will get the latest release of Mir with that.

Yunit is taking forward the work begun by Canonical on “convergence”. They are still in an exploratory phase, but the debs they’ve created for Debian Unstable use the current Mir 0.26 release.

As reported elsewhere there have been discussions with other projects who are interested in using Mir. It remains to see if, and in what way, those discussions develop.

The Future

For all of these projects the Mir team must be more responsive than it has been to the needs of those outside Canonical. I think, with the work done on MirAL, much of the technical side of that has been addressed. But we still have to prove ourselves in other ways.

There’s a new (0.27) release of Mir undergoing testing for release to the Ubuntu 17.10 series. This delivers a lot of the work that was “in progress” before Canonical’s focus shifted from Unity8 to miral-kiosk and marks the point of departure from our previous plans for a Mir 1.0. Mir 0.27 will not be released to other series, as we expect to ship Mir 1.0 in 17.10.

The other thing 0.27 offers is based on the efforts we’ve seen in UBports (and a PR from a former Mir developer that has joined the project): we’ve published the APIs needed to develop a “mir platform” out of the Mir source tree. That means, for example, developing a mir-on-wayland platform doesn’t require forking the whole of Mir. One specific platform that is now out-of-tree is the “mir-on-android” platform – from my experience with MirAL I know that having a real out-of-tree project helps prove things really work.

In addition, while we won’t be releasing Mir 0.27 to 17.04, I’ve included testing there, along with the Unity8 desktop to ensure that all the features required by a “real shell” remain intact.

Beyond Mir 0.27 the plan towards 1.0 diverges from past discussions. We are no longer planning to remove deprecated functions from the libmirclient ABI, instead we are working towards supporting Wayland clients directly.


In order to trace a problem[1] in the Mir stack I needed to build mesa to facilitate debugging. As the options needed were not entirely obvious I’m blogging the recipe here so I can find it again next time.

$ apt source libgl1-mesa-dri
$ cd mesa-17.0.3
$ QUILT_PATCHES=debian/patches/ quilt push -a
$ sudo mk-build-deps -i
$ ./configure --with-gallium-drivers= --with-egl-platforms=mir,drm,rs
$ make -j6
$ sudo make install && sudo ldconfig

[1] The stack breaking with EGL clients when the Mir server is running on a second host Mir server that is using the mesa-kms plugin and mesa is using the intel i965 driver. (LP: #1699484)

Mir release 0.26.3

Mir 0.26.3 for all!

By itself Mir 0.26.3 isn’t a very interesting release, just a few minor bugfixes: [https://launchpad.net/mir/0.26/0.26.3]

The significant thing with Mir 0.26.3 is that we are making this version available across the latest releases of Ubuntu as well as 17.10 (Artful Ardvark). That is: Ubuntu 17.04 (Zesty Zapus), Ubuntu 16.10 (Yakkety Yak) and, last but not least, Ubuntu 16.04LTS (Xenial Xerus).

This is important to those developing Mir based snaps. Having Mir 0.26 in the 16.04LTS archive removes the need to build Mir based snaps using the “stable-phone-overlay” PPA.

Fairer than Death

The changes at Canonical have had an effect both on the priorities for the Mir project and on the resources available for future development. We have been meeting to make new plans. In short:

Mir is alive, there are Canonical IoT projects that use it. Work will continue on Mir to support these and on cleaning and upstreaming the distro patches Ubuntu carries to support Mir.

Canonical are no longer working on a desktop environment or phone shell. However we will maintain the existing support Mir has for compositing and window management. (We’re happy to receive PRs in support of similar efforts.)