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Posts tagged with 'mir'

Alan Griffiths

MirAL 1.3.1

There’s a bugfix MirAL release (1.3.1) available in ‘Zesty Zapus’ (Ubuntu 17.04) and the so-called “stable phone overlay” ppa for ‘Xenial Xerus’ (Ubuntu 16.04LTS). MirAL is a project aimed at simplifying the development of Mir servers and particularly providing a stable ABI and sensible default behaviors.

Unsurprisingly, given the project’s original goal, the ABI is unchanged.

The bugfixes in 1.3.1 fall are:

In libmiral a focus management fix:

When a dialog is hidden ensure that the active window focus goes to the parent. (LP: #1671072)

In the miral-shell example, two crashes fixed:

If a surface is deleted before its decoration is painted miral-shell can crash, or hang on exit (LP: #1673038)

If the specified “titlebar” font doesn’t exist the server crashes (LP: #1671028)

In addition a misspelling of “management” has been corrected:

SetWindowManagmentPolicy => SetWindowManagementPolicy

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Alan Griffiths

Mir and Zesty

Mir is continuing to make progress towards a 1.0 release and, meanwhile, Zesty Zapus (Ubuntu 17.04) is continuing to make progress towards final freeze.

Currently the version of Mir in Zesty is 0.26.1 and we’re not planning any major changes for the 17.04 series. We’re probably going to make a bugfix release (0.26.2). The other possibility is that work on supporting hybrid graphics is completed in time for adequate testing for 17.04. In the latter case we’ll be releasing Mir 0.27 to get that shipped.

For this and other reasons it isn’t yet clear whether there will be a 0.27 release before we move to 1.0.

The significance of a 1.0 release is that it will be the time we break the mirclient ABI and delete a lot of deprecated APIs, which will have a significant effect on downstream projects. We’ve tried to prepare by marking the deprecations in 0.26 and updating downstream projects accordingly. But while this preparation means that most downstream projects “only need recompiling” this is something we want to do at the start of a release cycle, not at the end.

The argument for a 0.27 release is that there is functionality we want to release and that this can be done without the disruption of an ABI break. So even if we don’t release 0.27 for 17.04 we may well do so once 17.10 is “open” in order to make this work available for Unity8 developers to use.

Either way, sometime early in the 17.10 cycle we’re going to release Mir 1.0. This will clear the way for Mir support in Mesa and Vulkan.

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Alan Griffiths

MirAL 1.3

There’s a new MirAL release (1.3.0) available in ‘Zesty Zapus’ (Ubuntu 17.04) and the so-called “stable phone overlay” ppa for ‘Xenial Xerus’ (Ubuntu 16.04LTS). MirAL is a project aimed at simplifying the development of Mir servers and particularly providing a stable ABI and sensible default behaviors.

Unsurprisingly, given the project’s original goal, the ABI is unchanged.

The changes in 1.3.0 fall are:

Support for “workspaces”

This is part of the enabling “workspaces” for Unity8 desktop. MirAL doesn’t provide fancy transitions and spreads, but you can see some basic workspace switching in the miral-shell example program:

$ apt install miral-examples
$ miral-app

There are four workspaces (corresponding to F1-F4) and you can switch using Meta-Alt-[F1|F2|F3|F4], or switch taking the active application to the new workspace using Meta-Ctrl-[F1|F2|F3|F4].

Support for “previous window in application”

You can now use Alt-Shift-` to switch to the previous in an application.

miral-shell adds a background

miral-shell now uses its background for a handy guide to the available keyboard shortcuts.

Bug fixes

Two bug fixes related to shutdown problems: one deals with a possible race in libmiral code, the other works around a bug in Mir.

  • [libmiral] Join internal client threads before server shutdown (LP: #1668651)
  • [miral-shell] Workaround for crash on exit (LP: #1667645)

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Alan Griffiths


mircade, miral-kiosk and

mircade is a proof-of-concept game launcher for use with miral-kiosk. It looks for installed games, works out if they use a toolkit supported by Mir and allows the user to play them.

miral-kiosk is a proof-of-concept Mir server for kiosk style use. It has very basic window management designed to support a single fullscreen application. is a packaging system that allows you to package applications (as “snaps”) in a way that runs on multiple linux distributions. You first need to have snapcraft installed on your target system (I used a dragonboard with Ubuntu Core as described in my previous article).

The mircade snap takes mircade and a few open games from the Ubuntu archive to create an “arcade style” snap for playing these games.

Setting up the Mir snaps

The mircade snap is based on the “Mir Kiosk Snaps” described here.

Mir support on Ubuntu Core is currently work in progress so the exact incantations for installing the mir-libs and mir-kiosk snaps to work with mircade varies slightly from the referenced articles (to work around bugs) and will (hopefully) change in the near future. Here’s what I found works at the time of writing:

$ snap install mir-libs --channel edge
$ snap install mir-kiosk --channel edge --devmode
$ snap connect mir-kiosk:mir-libs mir-libs:mir-libs
$ sudo reboot

Installing the mircade-snap

I found that installing the mircade snap sometimes ran out of space on the dragonboard /tmp filesystem. So…

$ TMPDIR=/writable/ snap install mircade --devmode --channel=edge
$ snap connect mircade:mir-libs mir-libs:mir-libs
$ snap disconnect mircade:mir;snap connect mircade:mir mir-kiosk:mir
$ snap disable mircade;sudo /usr/lib/snapd/snap-discard-ns mircade;snap enable mircade

Using mircade on the dragonboard

At this point you should see an orange screen with the name of a game. You can change the game by touching/clicking the top or bottom of the screen (or using the arrow keys). Start the current game by touching/clicking the middle of the screen or pressing enter.

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kevin gunn

1)Put the latest ubuntu-core image for dragonboard on boot (you’ll want a screen and keyboard at least)

You can find the image here

Make sure you’re on the latest with the following

ssh$ snap refresh core


2)Then install the mir-libs and mir-kiosk


ssh$ snap install mir-libs --channel=edge
ssh$ snap install mir-kiosk --channel=edge
ssh$ snap install ubuntu-app-platform



3)Using the snap built from this branch  

This particular snap

Seemed to work find, download copy over and install

ssh$ snap install webbrowser-app*.snap --devmode --dangerous


4) NOTE: because of bug  you have to do the following, hopefully the pull request will get merged soon and this step we can remove


ssh$ snap disconnect webbrowser-app:mir
ssh$ snap disconnect webbrowser-app:platform
ssh$ snap connect webbrowser-app:mir mir-kiosk:mir
ssh$ snap connect webbrowser-app:platform ubuntu-app-platform:platform
ssh$ snap disable webbrowser-app
ssh$ snap enable webbrowser-app


5) Now launch and use

$ webbrowser-app


If you should experience a crash of the web browser, just restart with the same command. Also, you will see some spew at the console you may ignore from the browser launching related to audio and Qt stuff.


Debugging: if you should find things aren’t working as expected, as in you do not see the web browser. Try rebooting first, which should auto launch mir-kiosk, then repeat the connection process and launching the browser. If that still doesn’t work, inspect all the connections via ssh$ snap interfaces and make sure mir-kiosk:mir-libs, webbrowser-app:mir-kiosk, webbrowser-app:ubuntu-app-platform, webbrowser-app:mir-libs are all connected as expected. Feel free to ping me or others on freenode at #snappy or #ubuntu-unity or #ubuntu-mir

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Alan Griffiths

MirAL 1.0

There’s a new MirAL release (1.0.0) available in ‘Zesty Zapus’ (Ubuntu 17.04) and the so-called “stable phone overlay” ppa for ‘Xenial Xerus’ (Ubuntu 16.04LTS). MirAL is a project aimed at simplifying the development of Mir servers and particularly providing a stable ABI and sensible default behaviors.

Surprisingly, given the project’s original goal, the ABI is changed. This allowed us to address a couple of minor issues and the timing seemed good as downstreams are faced with Mir-0.25 moving some necessary APIs from libmircommon to the more ABI stable libmircore.

The changes in 1.0.0 are:

  1. The default movement of child windows can be overridden by the window management policy;
  2. A new “miral-app” script that runs the miral example servers as an application on an existing desktop;
  3. Bug fix LP: #1646431 “Examples fail to start under Unity8”;
  4. Bug fix LP: #1646735 “[miral-shell –window-manager tiling] windows are not correctly constrained to tiles”; and
  5. A couple of deprecated APIs have been removed.

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Alan Griffiths

Testing for Mir

Need a Mir server?

A couple of times in the last week I’ve been asked about a Mir server for testing. These requests have been from folks wanting to test their client-side work against Mir.

Most application developers will be using a toolkit or other graphics development library and not care if they are running on X11, Mir or even Windows. But the developers of those libraries will want to test with Mir.

For this purpose, the simplest Mir server to use is miral-shell. If you’re on Ubuntu Zesty Zapus then this is readily available:

$ sudo apt install miral-examples mir-graphics-drivers-desktop qtubuntu-desktop

If you’re on an earlier version of Ubuntu then you either need a ppa (such as the “stable phone overlay”) or, less risky to your system, just build and install it yourself. (If you’re not on Ubuntu this is still possible: there are some pointers here.)

What does miral-server provide?

Currently miral-server is the only Mir server to offer libmiral’s “basic window management”. That unique status is due to change real soon as this implementation is being merged into Unity8.

The simplest way way to run miral-shell is using Mir’s “Mir on X” support. From a terminal window just type:

$ miral-shell

Then you can connect your application from another terminal:

$ miral-run <application>

You should see your application appear in the “Mir on X” window.

A lot of the current work is focused on the placement of windows (menues, popup, etc.) and to help with this there’s a facility to trace the window management calls. Start miral-shell like this:

$ miral-shell --window-management-trace

And all the window management events and decisions are logged.

Another interesting option is to use a “tiling” window manager:

$ miral-shell --window-manager tiling

Which has a completely different approach to laying out the application windows.

For a full list of the option:

$ miral-shell --help

Documentation of the Mir “toolkit”API

A related question I’ve been asked is for documentation of the libmirclient API. You can find the documentation like this:

$ sudo apt install mir-doc
$ xdg-open /usr/share/doc/mir-doc/html/group__mir__toolkit.htm

This will open the default browser on the relevant page.

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kevin gunn

more sample client updates

I can’t even remotely take credit for this. Alberto from the Mir team took the mir-client snap and updated to utilize the mir-libs snap through the content interface. This is helpful as a guide for others who want to avoid making useless copies of libraries in a mir-client app snap. He also added some additional example client applications to run on the mir-kiosk, along with using the snap set command to dynamically change those from the command line. I’ve updated the mir-snaps wiki on how to utilize this. enjoy! If you wanna discuss or have issues, find me (kgunn) on freenode #ubuntu-mir

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Alan Griffiths

Miral on Dragonboard

Miral on Dragonboard

Having seen Kevin Gunn’s post on the mir-kiosk I thought I’d give it a try.  This is what I found.


First, I dug out the Dragonboard I’d been testing Mir on a few months ago from a drawer and borrowed the Logitech k400r keyboard I use in my “den”. (This is convenient there because it provides both keyboard and mouse input from one device I can use from my lap.)

There was still a micro SD card in the board, so I extracted that and inserted it via a micro SD adapter into my desktop. Then I downloaded the dragonboard image from the link in Kevin’s article, verified the checksum and discovered that “Disk Image Writer” was the default app for opening the file. That sounded promising, so I opened the file with it, selected the SD card and started writing the image.

While that was going on I found an HDMI/VGA adapter and an old monitor to connect to the Dragonboard and started checking how to install from the SD. The main thing was to get the boot switches on the back of the board into 0110 positions (which means it will boot from the micro SD card).

With all that ready I went to brew tea while “Disk Image Writer” continued reporting progress.

It boots!

Returning with my tea I found that the image was written, so I disconnected the card and put it into the Dragonboard and connected the power.

I was greeted by a blank screen.

After a bit of experimentation I found that I need to connect to a real HDMI monitor during boot, but can switch to the adapter+VGA monitor after that. Annoying, but it works. (As I’m not yet sure where the fault lies I won’t mention the brands.)

Setup is a few simple questions, the only annoyance I had was that the keyboard layout defaults to US which makes typing my network password “interesting” on a UK keyboard.

One thing that could be a trap is that it asked for my email address to connect to the snap store. I’ve never been there before but I took a punt and used my canonical email address. That seemed to work and pick up the credentials on Launchpad.

That meant I could ssh into the Dragonboard from my desktop.

Installing miral-kiosk

Installing the mir libraries and the miral kiosk looks really easy using the commands Kevin provides (in the ssh session):

$ sudo snap install mir-libs --channel=edge --devmode
error: cannot perform the following tasks:
- Download snap "mir-libs" (3) from channel "edge" (unexpected EOF)

Actually, before that message was shown I got one estimating the download time at over an hour! Try again…

$ sudo snap install mir-libs --channel=edge --devmode
mir-libs (edge) 0.1 from 'albaguirre' installed

That’s better! (And only took a few seconds.)

$ sudo snap install mir-kiosk --channel=edge --devmode
mir-kiosk (edge) 0.1 from 'albaguirre' installed

Wow, I see the orange miral-kiosk startup “splash” and a mouse pointer! miral-kiosk is running on the Dragonboard.

A Client Application

To get a client application kg’s blog continues with the instructions:

“Download the appropriate architecture of the mir-client snap and then copy that over to your running ubuntu-core image. “

In this case we’re arm64, so I followed the link and picked out mir-client_0.24.1_arm64.snap. And then copied it to the dragonboard (back to a desktop terminal session):

$ scp Downloads/mir-client_0.24.1_arm64.snap alan-griffiths@
mir-client_0.24.1_arm64.snap 100% 103MB 173.7KB/s 10:05

That took an unexpectedly long time. Back to ssh session:

$ sudo snap install mir-client_0.24.1_arm64.snap --channel=edge --devmode 
mir-client 0.24.1 installed

And there it is – kg’s sample client application running on miral-kiosk.

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kevin gunn

If you’ve been following along, you’ll know that we’ve put some snap work in to show how you might use Mir as a framework to build a kiosk style product. This post touches on a couple of recent evolutions.

First, there’s been recent work in improving Mir’s API stability at the server level, to be a true toolkit for shells through Miral which you can read about here. And you can read about the latest Miral 0.3 release here. Part of Miral provides 2 default shell implementations. One is miral-shell and the other is miral-kiosk. Miral-kiosk, as the name suggests, is a very minimal shell, keeping the footprint and complexity low. Hence it’s perfect for targeting products requiring simple, single application user interfaces. So we’ve created a snap utilizing this, named “mir-kiosk”.

Eventually Miral will become part of Mir itself, we just need to work through supported trusted prompts in more complex shell use cases (which is happening as I type). But the point of this post, is demonstrating miral-kiosk in a snap. If anyone reading this is considering using Mir snaps for production in a kiosk style product, I would recommend miral-kiosk as the preferred method. The same confinement achieve before still exists and you can run the same example applications.

Second, with the advent of the content interface available in the latest snapd release we are moving out the Mir libraries into their own snap that can be leveraged by the shell and mir-clients. This will make sure the Mir libraries stay in sync with one another and there’s a little deduplication gain so there’s not a lot of snaps with copies of Mir libraries as stage packages. This snap’s name is “mir-libs”.

Both the mir-kiosk & mir-libs snaps are available in the snap store. It can be demonstrated using the same mir-client snap that’s been used before in other posts.

Now, to experience this you need to download the latest ubuntu-core image, which is Release Candidate 2 (RC2). Download the appropriate architecture of the mir-client snap and then copy that over to your running ubuntu-core image. You can then ssh into your device/VM and install in this particular order.

$ snap install mir-libs --channel=edge --devmode
$ snap install mir-kiosk --channel=edge --devmode
$ snap install mir-client_0.24.1_amd64.snap --devmode --dangerous


At this point you should witness PhotoViewer running on mir-kiosk using mir-libs via content interface on your device or VM.

One last note, you might notice I’ve added –devmode to the installation steps here, that is due to a small regression in the RC2 image, it’s a bug that’s actively being worked. Confinement is still maintained with the the mir-kiosk snap.


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Alan Griffiths

There are a few “gotchas” in running X11 applications (via Xmir) on Mir servers so I’m sharing a short script to make it easier.

The following script will work with the example servers from the “mir-demos” package, the miral-shell (from “miral-examples”) and my own egmde project. (With Unity8 there’s a little more to it but as there is existing “magic” in place for launching X11 applications I won’t bother to discuss it further.)

The principle issue is that each Xmir session is seen as a single application by the Mir server, so we need to create an Xmir server for each application for everything to make sense. And that means each application needs a separate port to connect to its Xmir server.

For this to work you need to have a Mir server running, and have Xmir installed.

Here’s the script:

$ cat ~/bin/Xmir-run
while [ -e "/tmp/.X11-unix/X${port}" ]; do
    let port+=1

Xmir -rootless :${port} & pid=$!
DISPLAY=:${port} $*
kill ${pid}

The first part of this script finds an available port to run Xmir on.

The next part starts an Xmir server in “rootless” mode and remembers the pid.

Then we run the command passed to the script until it exits.

Finally, we kill the Xmir server.


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kevin gunn

a better kiosk demo

Hey just having more fun snapping on dragonboard. I’ve updated the mir-client snap to use a Qt demo that is probably a bit more like what a kiosk style application might be. It’s the photoviewer on dragonboard as an example. Which improved not only the demo experience but provides developers a better guide since it actually uses the qmake plugin of snapcraft to build the demo from source. I can’t emphasize how easy it was to modify my snapcraft project to add this to the demo. Again, good ‘ol mir-snaps wiki can be used as a guide. And if you don’t want to build, you can grab my personal builds of these snaps for arm64 for mir-server snap and mir-client-snap respectively.

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kevin gunn

hey just a very quick update. Had some more time to play around today and touch is working after all (only difference is I left my usb keyboard disconnected today so maybe it was getting confused)

Anyhow, here’s videos of Qt clocks with touch and Qt samegame with touch

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kevin gunn

OK, I’m really overdue on posting something about this as I’ve had _something_ running on the dragonboard 410c for a while. If you don’t know about dragonboard you can check out dragonboard from 96boards .

So dragonboard is targeted to be a supported reference board by our Snappy team and they’re in the process of pushing out beta images to play with in the 16 series. I had been concerned that we I was going to have to go and build the graphics drivers into our Ubuntu core snap. When I started I wasn’t even sure of the state of the freedreno drivers vs closed source vendor drivers. But as luck would have it, someone quite recently had turned on the gallium drivers to be built and package as part of the Ubuntu distro, which means I got the freedreno drivers with no effort! Lots of love to Rob Clark for all the work he’s done on freedreno (if your interested in learning more  check out freedreno on github ).

So getting a devmode mir snap demo up and running was relatively painless. However, I do want to say I found a little difference in my runs amd64 VM vs the native arm64. This resulted in some tweaks to the mir interface in snapd (which had already landed and should be in the next snapd release). Also, never use setterm when developing with Mir, that create all sorts of chaos for me 🙂 I had used setterm for convenience to prevent the screen from blanking, ended up causing failures when I was working on making sure the mir snaps could run confined.

If you follow the good ol’ mir snaps wiki, you can easily duplicate this – running the mir snaps fully confined on dragonboard core snap. Also, I wanted to point out again there are other Qt demos you can try besides the clock app – simply modify the helper file in the client example (client-start) to be something besides “clock”, for example “maroon” or “samegame”. You can do this with an HDMI monitor and mouse attached  like in this  video of various Qt apps as mir-client snaps running on dragonboard . Still need to investigate some mouse oddities that seem to only occur with apps other than clock.

And lastly, I got new toy over the weekend. I ordered a 7″ touch screen from adafruit. Here’s a quick video of the 7″ display attached. I need to tinker with it to see about getting the touch to work, but it was nice to just hook it together and the display come up.

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Alan Griffiths


A feature added to the lp:miral trunk yesterday is making life a lot easier for developers working on MirAL based servers, and the toolkit extensions that support Mir. The feature is:

miral-shell --window-management-trace

Actually, the –window-management-trace switch will work with any MirAL base server (so miral-kiosk and egmde support it too).

What this does is cause the server to log every interaction with the window management policy – all the notifications it receives and all the calls it makes to the tools as a result.

This means that it is easy to find out that, for example, a “modal” gtk based dialog window is being created without specifying a parent. (Which is why the behaviour isn’t quite as expected – Mir servers will treat it as non-modal.)

To use this feature before the next MirAL release you do need build it yourself, but this only takes a minute (depending on your kit).It really is the easiest way to see exactly what is going on and why.

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kevin gunn

So first, if you didn’t catch it, series 16 Ubuntu Core beta images are available here

I just verified the Mir snaps are functioning and made some small updates to match here

One of which being a command line switch for installing the snaps locally… –dangerous, what a great flag name 🙂

Also, I made some updates to the snaps themselves to check for the architecture from $SNAP_ARCH and then set up all the correct paths. So this means the scripts will work properly on the various archs without having to tinker. I’ve also changed the mir-client snap specifically to pull the demos from the archive, this way you’ll also get the right binary for the right arch as well.



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Alan Griffiths

An Example Mir Desktop Environment

The world of Mir

Mir is a set of libraries supporting the development of display servers, desktop environments, shells and implementing toolkit support for applications running on them.

As part of their “convergence” of computing devices Canonical are committed to providing Mir on a range of platforms including desktops, phones, tablets and “the internet of thing”. You can read about the work to provide it as a “snap” in the “internet of things” on Kevin Gunn’s blog [kg’s blog].

Toolkits and other “client” platforms that have support for Mir include GTK, Qt and SDL – which mean that applications using these can work on Mir. There’s a separate Xmir project to support X11 applications on Mir.

On the driver side of things Mir works with Mesa on desktop-like systems and, using libhybris, on an android based stack on a number of devices. The Mesa support is a work in progress and Ubuntu carries a set of patches to enable it. There are some notes about how to incorporate these on other platforms here: [Enabling Mir EGL]. Work is in progress to upstream Mir support.

The “Mir Abstraction Layer” (MirAL) packages the server-side functionality in a way that makes it easy to use. My previous post[MirAL] introduced MirAL in more detail.

Before we begin

If you want to experiment with this code I suggest using Ubuntu 16.04 or later on desktop for the reasons mentioned above. On an Ubuntu phone you can use the current stable version with this code, but doing development on a phone is a whole other article. On other distributions you likely need to patch Mesa and rebuild toolkits with Mir support enabled.

Having got an Ubuntu desktop you also need to install MirAL, at present this is not available from the Ubuntu archives, so you have to build and install it yourself:

$ sudo apt-get install devscripts equivs bzr
$ bzr branch lp:miral
$ sudo mk-build-deps -i --build-dep miral/debian/control
$ mkdir miral/build
$ cd miral/build
$ cmake ..
$ make
$ sudo make install

egmde [Example Mir Desktop Environment]

To illustrate MirAL I’m going to show what is involved in writing a (very simple) window manager. It runs on desktops, tablets and phones and supports keyboard, mouse and touch input. It will support applications using the GTK and Qt toolkits, SDL applications and (using Xmir) X11 applications.

The full code for this example is available on github:

$ git clone

Naturally, the code is likely to evolve, especially if I write a follow-up article but the version presented here is tagged v1.0. Assuming that you’ve MirAL installed as described above you can build it as follows:

$ mkdir egmde/build
$ cd egmde/build
$ cmake ..
$ make

The example code

A lot of the functionality (default placement of windows, menus etc.) comes with the MirAL library. For this exercise we’ll implement one class and write a main function that injects it into MirAL. The main program looks like this:

int main(int argc, char const* argv[])
    miral::MirRunner runner{argc, argv};

    return runner.run_with(

Yes, you’ve guessed it: the class we’ll be implementing is ExampleWindowManagerPolicy. It looks like this:

class ExampleWindowManagerPolicy : public CanonicalWindowManagerPolicy
    using CanonicalWindowManagerPolicy::CanonicalWindowManagerPolicy;

    // Switch apps  : Alt+Tab
    // Switch window: Alt+`
    // Close window : Alt-F4
    bool handle_keyboard_event(MirKeyboardEvent const* event) override;

    // Switch apps  : click on the corresponding window
    // Switch window: click on the corresponding window
    // Move window  : Alt-leftmousebutton drag
    // Resize window: Alt-middle_button drag
    bool handle_pointer_event(MirPointerEvent const* event) override;

    // Switch apps  : tap on the corresponding window
    // Switch window: tap on the corresponding window
    // Move window  : three finger drag
    // Resize window: three finger pinch
    bool handle_touch_event(MirTouchEvent const* event) override;

    void pointer_resize(Window const& window, Point cursor, Point old_cursor);
    void resize(WindowInfo& window_info, Point new_pos, Size new_size);

    // State held for move/resize by pointer
    Point old_cursor{};
    bool resizing = false;
    bool is_left_resize = false;
    bool is_top_resize = false;

    // State held for move/resize by touch
    int old_touch_pinch_top = 0;
    int old_touch_pinch_left = 0;
    int old_touch_pinch_width = 0;
    int old_touch_pinch_height = 0;

For this simple example the only functionality we’ll be providing is the handling of input events to allow the user to switch between applications and windows and to resize and move windows.

We only need to provide three handle_XXX_event() functions as we’re relying on the default behaviour for everything else. The first of these functions is the simplest:

bool ExampleWindowManagerPolicy::handle_keyboard_event(MirKeyboardEvent const* event)
    auto const action = mir_keyboard_event_action(event);
    auto const shift_state = mir_keyboard_event_modifiers(event) & shift_states;

    if (action == mir_keyboard_action_down &&
        shift_state == mir_input_event_modifier_alt)
        switch (mir_keyboard_event_scan_code(event))
        case KEY_F4:
            return true;

        case KEY_TAB:
            return true;

        case KEY_GRAVE:
            return true;


    return false;

I don’t think this needs a lot of explanation: we select key presses while only the Alt button is pressed and act according to the button pressed.

The other two functions are a bit longer as they need to remember some state in order to interpret mouse or touchpad gestures. There’s in them nothing I consider worth pointing out here and the full code is available on github. There’s not much:

$ wc *
15 28 446 CMakeLists.txt
357 957 10528 egmde.cpp
372 985 10974 total

I have much to compare it with, bit I don’t think 372 lines is bad for a functional window manager.

Running egmde

Once egdme has been built you can run it in two modes: the simplest is the “Mir-on-X” mode:

$ ./egmde

This will produce a rather boring black “Mir-on-X” window. You can attach Mir clients to this:

$ miral-run gnome-system-monitor
$ miral-run gnome-terminal

These will run in the window and make it less boring. You can also have egmde launch them when it starts as follows:

$ ./egmde --startup gnome-terminal:gnome-system-monitor

If you don’t want to run in a window under X11 you can also give egmde access to your hardware directly by running it as root and specifying a “virtual terminal”. But I think it is probably better to use mir_demo_server in “system-compositor” mode to handle the hardware and launch egdme a normal user.

$ sudo apt install mir-demos
$ sudo mir_demo_server --vt 3 --window-manager system-compositor

You’ll find this switches you to vt3, switch back with Ctrl-Alt-F7 and, from another terminal, you can connect egdme to this. (We need the VT switch here as the host mir_demo_server is paused while X11 is in control.)

$ sudo chvt 3&&./egmde --host /tmp/mir_socket --startup gnome-terminal

You don’t have to start the gnome-terminal, but it is convenient as you can launch other applications. For example:

$ mir_demo_client_eglplasma


I hope that the egmde example is enough to spark someone’s interest in MirAL and to provide a starting point for developing something more ambitious.

Much of what has been discussed is a work-in-progress, especially MirAL which I hope to get added to the Ubuntu archives soon. I am optimistic this will happen as it is in the interests of both Canonical and the wider community to have a stable server ABI against which to write desktop environments (including Unity8). Indeed I’ve been working with the main developer of the QtMir abstraction layer to migrate it to MirAL.

Similarly, a significant portion of the work needed on Mesa to support Mir is similar to the work to support Wayland/Weston and everyone would benefit from cleaning this up (and, for example, removing hard dependencies on X11).

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Alan Griffiths

MirAL: Mir is not all about Unity8

Introducing The Mir Abstraction Layer

The principle Open Source project I’ve been working on for the last few years is Mir. Mir is a library for writing Linux display servers and shells that are independent of the underlying graphics stack. It fits into a similar role as an X server or Weston (a Wayland server) but was initially motivated by Canonical’s vision of “convergent” computing.

The Mir project has had some success in meeting Canonical’s immediate needs – it is running in the Ubuntu Touch phones and tablets, and as an experimental option for running the Unity8 shell on the desktop. But because of the concentration of effort on delivering the features needed for this internal use it hasn’t really addressed the needs of potential users outside of Canonical.

Mir provides two APIs for users: the “client” API is for applications that run on Mir and that is largely used by toolkits. There is support for Mir in the GTK and Qt toolkits, and in SDL. This works pretty well and the Mir client API has remained backwards compatible for a couple of years and can do so for the foreseeable future.

The problem is that the server-side ABI compatibility is broken by almost every release of Mir. This isn’t a big problem for Canonical, as the API is fairly stable and both Mir and Unity8 are in rapid development: rebuilding Unity8 every time Mir is released is a small overhead. But for independent developers the lack of a stable ABI is problematic as they cannot easily synchronize their releases to updates of Mir.

My answer to this is to provide a stable “abstraction layer” written over the top of the current Mir server API that will provide a stable ABI. There are a number of other goals that can be addressed at the same time:

  • The API can be considerably narrowed as a lot of things can be customized that are of no interest to shell development;
  • A more declarative design style can be followed than the implementation focused approach that the Mir server API follows; and,
  • Common facilities can be provided that don’t belong in the Mir libraries.

At the time of writing the Mir Abstraction Layer (miral) is a proof-of-concept, but work is in progress to package an initial version that can support the functionality needed by some examples, and by qtmir (the Qt support used by Unity8).

Building and using MirAL

These instructions assume that you’re using Ubuntu 16.04LTS or later, I’ve not tested earlier Ubuntu versions or other distributions.

You’ll need a few development and utility packages installed, along with the Mir development packages:

$ sudo apt-get install cmake g++ make bzr python-pil uuid-dev libglib2.0-dev
$ sudo apt-get install libmirserver-dev libmirclient-dev mirtest-dev
$ sudo apt-get install mir-graphics-drivers-desktop libgles2-mesa-dev

(If you’re working on a phone or tablet use mir-graphics-drivers-android in place of mir-graphics-drivers-desktop.)

With these installed you can checkout and build miral:

$ bzr branch lp:miral
$ mkdir miral/build
$ cd  miral/build
$ cmake ..
$ make

This creates in the lib directory and an example shell (miral-shell) in the bin directory. This can be run directly:

 $ bin/miral-shell

With the default options this runs in a window on X (which is convenient for development).

The miral-shell example is simple, don’t expect to see a sophisticated launcher by default. You can start mir apps from the command-line. For example:

 $ bin/miral-run gnome-terminal

That’s right, a lot of standard GTK+ applications will “just work” (the GDK toolkit has a Mir backend). Any that assume the existence of an X11 and bypass the toolkit by making X11 protocol calls will have problems though.

To exit from miral-shell press Ctrl-Alt-BkSp.

To run independently of X11 you need to grant access to the graphics hardware (by running as root) and specify a VT to run in. For example:

$ sudo bin/miral-shell --vt 4 --arw-file --file $XDG_RUNTIME_DIR/mir_socket

For convenient testing there’s a “testrun” script that wraps this command to start the server (as root) and then launches the gnome-terminal (as the current user):

$ ../scripts/testrun

Running applications on MirAL

If you have a terminal session running in the MirAL desktop (as described above) you can start programs from it. GTK, Qt and SDL applications will “just work” provided that they don’t bypass the toolkit and attempt to make X11 protocol calls that are not available.

$ gedit
$ 7kaa

From outside the MirAL session the “miral-run” script sets a few environment variables to configure the Mir support in the various toolkits. (There’s some special treatment for gnome-terminal as starting that can conflict with the desktop default.)

$ bin/miral-run gnome-calculator
$ bin/miral-run 7kaa

There are also some examples of native Mir client applications in the mir-demos package. These are typically basic graphics demos:

$ sudo apt-get install mir-demos
$ mir_demo_client_egltriangle

Support for X11 applications

If you want to run X11 applications that do not have native Mir support in the toolkit they use then the answer is Xmir: an X11 server that runs on Mir. First you need Xmir installed:

$ sudo apt install xmir

Then you can use the testrun script to start miral-shell with Xmir:

$ ../scripts/testrun -Xmir

This starts an X11 server on DISPLAY=:1. This is set in the terminal the script starts so that applications launched from it will automatically connect to miral through Xmir.

Running Qt applications

To run Qt applications under Mir you may need to install qtubuntu-desktop:

$ sudo apt-get install qtubuntu-desktop

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kevin gunn

Mir interface landed!

So the Mir interface has landed in snapd. This means that the mir-server snap can be downloaded and taken into use in a fully confined mode, along with matching mir-client snap. I’ve been keeping updated instructions here on the best way to operate and develop your mir-client snap. The one caveat is there’s still a snappy bug (launchpad bug# 1577897)  with snap auto-connections.  This means that you have to manually make the plug-slot connection of the mir-server and mir-client, and then restart the mir-client service. I’ve just uploaded a new mir-server snap which is on Mir version 0.23.5, it should be reflected in the store soon.

At any rate, I’d love to hear back from folks trying this out. In the coming weeks I’m hoping to spend some time on dragonboard and getting this working there.

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Christopher Halse Rogers

XMir Performance

Or: Why XMir is slower than X, and how we'll fix it

We've had a bunch of testing of XMir now; plenty of bugs, and plenty of missing functionality.

One of the bugs that people have noticed is a 10-20% performance drop over raw X. This is really several bits of missing functionality - we're doing a lot more work than we need to be. Oddly enough, people have also been mentioning that it feels "smoother" - which might be placebo, or unrelated updates, or might be to do with something in the Mir/XMir stack. It's hard to tell; it's hard to measure "smoother". We're not faster, but faster is not the same as smoother.

Currently we do a lot of work in submitting rendering from an X client to the screen, most of which we can make unnecessary.

The simple bit

The simple part is composite bypass support for Mir - most of the time unity-system-compositor does not need to do any compositing - there's just a single full-screen XMir window, and Mir just needs to flip that to the display. This is in progress. This cuts out an unnecessary fullscreen blit.

The complicated part is in XMir itself

The fundamental problem is the mismatch between rendering models - X wants the contents of buffers to be persistent; Mir has a GLish new-buffer-each-frame. This means each time XMir gets a new buffer from Mir it needs to blit the previous frame on first, and can't simply render straight to Mir's buffer. Now, we can (but don't yet) reduce the size of this blit by tracking what's changed since XMir last saw the buffer - and a lot of the time that's going to be a lot smaller than fullscreen - but there's still some overhead¹.

Fortunately, there's an way around this. GLX matches Mir's buffer semantics nicely - each time a client SwapBuffers it gets a shiny new backbuffer to render into. So, rather like Compiz's unredirect-fullscreen-windows option, if we've got a fullscreen² GLX window we can hand the buffer received from Mir directly to the client and avoid the copy.

Even better, this doesn't apply only to fullscreen games - GNOME Shell, KWin, and Unity are all fullscreen GLX applications.

As always, there are interesting complications - applications can draw on their GL window with X calls, and applications can try to be fancy and only update a part of their frontbuffer rather than calling SwapBuffers; in either case we can't bypass. Unity does neither, but Shell and KWin might.

Enter the cursor

In addition to the two unnecessary fullscreen blits - X root window to Mir buffer, Mir buffer to framebuffer - XMir currently uses X's software cursor code. This causes two problems. Firstly, it means we're doing X11 drawing on top of whatever's underneath, so we can't do the SwapBuffers trick. Secondly, it causes a software fallback whenever you move the cursor, making the driver download the root window into CPU accessible memory, do some CPU twiddling, and then upload again to GPU memory. This is bad, but not terrible, for Intel chips where the GPU and CPU share the same memory but with different caches and layouts. It's terrible for cards with discrete memory. Both these problems go away once we support setting the HW cursor image in Mir.

Once those three pieces land there shouldn't be a meaningful performance difference between XMir-on-Mir and X-on-the-hardware.

¹: If we implemented a single-buffer scheme in Mir we could get rid of this entirely at the cost of either losing vsync or blocking X rendering until vsync. That's probably not a good tradeoff.

²: Technically, if we've got a GLX client whose size matches that of the underlying Mir buffer. For the moment, that means "fullscreen", but when we do rootless XMir for 14.04 all windows will be backed by a Mir buffer of the same size.

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