324eeaa0cd
When the user switches away from the VT where wlroots is running,
the new DRM master may mutate the KMS state in an arbitrary manner.
For instance, let's say wlroots uses the following connector/CRTC
mapping:
- CRTC 42 drives connector DP-1
- CRTC 43 drives connector DP-2
Then the new DRM master may swap the mapping like so:
- CRTC 42 drives connector DP-2
- CRTC 43 drives connector DP-1
wlroots needs to restore its own state when the user switches back.
Some state is attached to wlr_drm_crtc (e.g. current FB), so reading
back and adopting the CRTC/connector mapping left by the previous DRM
master would be complicated (this was the source of other bugs in the
past, see [1]).
With the previous logic, wlroots merely tries to restore the state
of each connector one after the other. This fails in the scenario
described above: the kernel refuses to use CRTC 42 for DP-1, because
that CRTC is already in-use for DP-2.
Unfortunately with the legacy uAPI it's not possible to restore the
state in one go. We need to support both legacy and atomic uAPIs, so
let's fix the bug for the legacy uAPI first, and then improve the
situation for the atomic uAPI as a second step [2].
We need to disable the CRTCs we're going to switch the connectors for.
This sounds complicated, so let's just disable all CRTCs to simplify.
This causes a black screen because of the on/off modesets, but makes
VT switch much more reliable, so I'll take it.
[1]:
|
||
---|---|---|
.builds | ||
backend | ||
docs | ||
examples | ||
include | ||
protocol | ||
render | ||
tinywl | ||
types | ||
util | ||
xcursor | ||
xwayland | ||
.editorconfig | ||
.gitignore | ||
.gitlab-ci.yml | ||
CONTRIBUTING.md | ||
LICENSE | ||
meson.build | ||
meson_options.txt | ||
README.md | ||
wlroots.syms |
wlroots
Pluggable, composable, unopinionated modules for building a Wayland compositor; or about 60,000 lines of code you were going to write anyway.
- wlroots provides backends that abstract the underlying display and input hardware, including KMS/DRM, libinput, Wayland, X11, and headless backends, plus any custom backends you choose to write, which can all be created or destroyed at runtime and used in concert with each other.
- wlroots provides unopinionated, mostly standalone implementations of many Wayland interfaces, both from wayland.xml and various protocol extensions. We also promote the standardization of portable extensions across many compositors.
- wlroots provides several powerful, standalone, and optional tools that implement components common to many compositors, such as the arrangement of outputs in physical space.
- wlroots provides an Xwayland abstraction that allows you to have excellent Xwayland support without worrying about writing your own X11 window manager on top of writing your compositor.
- wlroots provides a renderer abstraction that simple compositors can use to avoid writing GL code directly, but which steps out of the way when your needs demand custom rendering code.
wlroots implements a huge variety of Wayland compositor features and implements them right, so you can focus on the features that make your compositor unique. By using wlroots, you get high performance, excellent hardware compatibility, broad support for many wayland interfaces, and comfortable development tools - or any subset of these features you like, because all of them work independently of one another and freely compose with anything you want to implement yourself.
Check out our wiki to get started with wlroots. Join our IRC channel: #sway-devel on Libera Chat.
A variety of wrapper libraries are available for using it with your favorite programming language.
Building
Install dependencies:
- meson
- wayland
- wayland-protocols
- EGL and GLESv2 (optional, for the GLES2 renderer)
- Vulkan loader, headers and glslang (optional, for the Vulkan renderer)
- libdrm
- GBM (optional, for the GBM allocator)
- libinput (optional, for the libinput backend)
- xkbcommon
- udev (optional, for the session)
- pixman
- libseat (optional, for the session)
- hwdata (optional, for the DRM backend)
If you choose to enable X11 support:
- xwayland (build-time only, optional at runtime)
- libxcb
- libxcb-render-util
- libxcb-wm
- libxcb-errors (optional, for improved error reporting)
Run these commands:
meson build/
ninja -C build/
Install like so:
sudo ninja -C build/ install
Contributing
See CONTRIBUTING.md.