8a0d0ce987
This avoids having to hardcode the same fallbacks elsewhere multiple times when determining what formats might be suitable for a set of CRTCs. The formats_modifiers hash table is now guaranteed to be populated with at least something, so future code will not need to handle it being empty. The hardcoded fallback formats are a minimal set probably supported by most hardware. XRGB8888 is the format that, according to ancient lore, all DRM devices should support, especially if they don't have the capability to advertise otherwise. Mutter also hardcodes XRGB8888 as the GBM surface format, so it is already required on primary GPUs. XBGR8888 matches the most common OpenGL format, sans alpha channel since scanout hardware has not traditionally supported alpha. XBGR8888 is here also because Mutter hardcodes that format for secondary GPU outputs when using the CPU copy path. https://gitlab.gnome.org/GNOME/mutter/merge_requests/341
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 af 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.
License
Mutter is distributed under the terms of the GNU General Public License, version 2 or later. See the COPYING file for detalis.