wlx - Wayland Compositor Library

The "x" makes it sound cool

wlx is a work-in-progress and experimental Wayland compositor library, with a focus on advanced features currently not available in other similar projects. This is still at the proof of concept stage; you probably shouldn't take it too "seriously" yet.

Major Target Features

• Restart-in-place, without losing client state
• Full multi-GPU support, with hotplug
• Ability to recover from GPU resets
• "Good" explicit synchronization (with queues)
• Multi-thread capable? (Still haven't decided if this is a good idea or not)

Why not wlroots/libweston?

In order to implement restart-in-place, I need control of all Wayland protocol state (down to the protocol buffers), which means we cannot use libwayland-server and are forced to reimplement it ourselves. libweston and wlroots are very tightly coupled to libwayland-server, so it would be far more work to try remove that compared to rewriting the whole thing.

Explicit synchronization is also a pretty extreme change to commit state handling, which arguably makes a rewrite easier too.

Other goals

wlx is going to be very heavily inspired by the design of wlroots, but there are several parts of it I want to improve.

• No rendering API; provide a scene graph instead. I've gone on about this enough in wlroots.
• Make it much easier to bind to from other languages
  • No container_of types in the API (think wl_list and wl_signal)
  • Maybe at least 1 "official" binding to another language, to make sure we don't fuck it up too much.
• More focus on ABI stability
  • More opaque structs
• Avoid making the mistake that was how wlr_output works.
  • More thought about the lifetime of things that cross the API.
• (Optional) Dynamically loadable modules. Basically just to get optional dependencies, so people don't have to pull in a bunch of X11 shit to use a distro version of this, unless they really want to. Mainly just concerns the backends and Xwayland.
• Be more careful of the symbols we use, in case we're being linked statically.
• Allow "unity builds" to work. Honestly unity builds are a pretty stupid idea and are just a workaround to C++'s god-awful compile times (thanks to templates), but being able to cleanly build this way helps with the above point.

Nvidia?

Hahahaha

no

License

GPL-2.0-only.

Targets

Operating System

• Linux (glibc or musl)
• FreeBSD

The code is written to be as conformant to C17 and POSIX.1-2008 as possible, but there will be some minor exceptions, either from necessity or if the value gained from something non-portable is very high. I'll try to provide reasonable fallbacks.

Patches for other BSDs or libcs are welcome, but its just that I probably won't put a lot of effort into maintaining support for them, especially if the DRM/evdev support isn't there.

Session Managers

One of logind, elogind, or Consolekit2 is required for the tty session. I will not be accepting anything that will require us to have elevated priviledges via setuid or requires messing around with the tty ourselves.