a68a06cfc3
The KMS thread handles updates posted asynchronously, but it expects to only handle one such frame in flight from the compositor at a time. That means that the triple buffering state tracking in MetaOncreen, that keeps track of posted frames and when they become presented, must also account for posted frames that doesn't contain an actual primary plane pixel buffer. This was not the case, causing MetaOnscreenNative to post multiple frames to the KMS thread, which wasn't handled gracefully in certain situations. Before the KMS thread grows real support for it's own queue of separate updates, make sure we keep the contract to the KMS thread in MetaOnscreenNative, and only submit at most one KMS update for each CRTC each cycle, even when there are no actual primary plane changes. v2: Properly handle frame tracking when when KMS update empty v3: In the page flip callback, only set the presented frame to frames that has buffers. This is needed on older kernels which doesn't have drmModeCloseFB() which would otherwise disable the CRTC when presented frame with an actual buffer would be replaced with an "empty" frame, causing the frame with the buffer to be released, with the buffer along with it. Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/4334>
Mutter
Mutter is a Wayland display server and X11 window manager and compositor library.
When used as a Wayland display server, it runs on top of KMS and libinput. It implements the compositor side of the Wayland core protocol as well as various protocol extensions. It also has functionality related to running X11 applications using Xwayland.
When used on top of Xorg it acts as a X11 window manager and compositing manager.
It contains functionality related to, among other things, window management, window compositing, focus tracking, workspace management, keybindings and monitor configuration.
Internally it uses a fork of Cogl, a hardware acceleration abstraction library used to simplify usage of OpenGL pipelines, as well as a fork of Clutter, a scene graph and user interface toolkit.
Mutter is used by, for example, GNOME Shell, the GNOME core user interface, and by Gala, elementary OS's window manager. It can also be run standalone, using the command "mutter", but just running plain mutter is only intended for debugging purposes.
Contributing
To contribute, open merge requests at https://gitlab.gnome.org/GNOME/mutter.
It can be useful to first look at the GNOME Handbook and the documentation and API references below first.
Documentation
- Coding style and conventions
- Git conventions
- Code overview
- Building and Running
- Debugging
- Monitor configuration
- Multi-GPU
API Reference
- Meta: https://mutter.gnome.org/meta/
- Clutter: https://mutter.gnome.org/clutter/
- Cogl: https://mutter.gnome.org/cogl/
- Mtk: https://mutter.gnome.org/mtk/
Meetings
There are recurring meetings to discuss development of GNOME Shell, mutter and related components.
License
Mutter is distributed under the terms of the GNU General Public License, version 2 or later. See the COPYING file for detalis.