A real Xfce desktop

Tunix now boots straight into a full Xfce desktop. Not a demo widget, not a single window on a bare compositor the whole thing: xfwm4 managing windows, the panel with an applications menu, xfdesktop painting the backdrop, Thunar for files, and a real xfce4-terminal you can actually type into. And it runs on Xorg.

Getting here was the same game as the Wayland work: discover the kernel's missing pieces one crash at a time, then fill them in.

The road there

1. Xorg, VT-less. The modesetting driver drives our simpledrm-style /dev/dri/card0, but there is no second virtual terminal to switch to so the server runs without one, the way a seatd session would.
2. GTK 3 with the X11 backend. Our GTK was Wayland-only. Rebuilding cairo with the xlib backend and GTK with x11_backend=true got it drawing on X; the atk-bridge dependency (which drags in AT-SPI over D-Bus) was patched optional so we didn't have to port accessibility first.
3. The X client libraries. xcb-util, startup-notification, libICE/libSM, and libwnck-3 the plumbing the window manager and session management link against.
4. xfwm4. The window manager, running the XRender compositor with GLX off.
5. D-Bus and the session. libdbus plus a session bus, then garcon (the menu library), xfce4-panel, xfce4-session, xfdesktop, and xfsettingsd which quietly needed libxml2 for xkbregistry.
6. The finishing touches. VTE and xfce4-terminal, a Thunar file-manager daemon, and the genuine Xfce wallpaper.

The bugs worth remembering

Every X client refused to connect. libxcb reads the X setup reply with recv(), and our kernel only understood recvmsg on unix sockets; the mirror gap on the send side later blocked GDBus. On top of that, Xorg binds an abstract socket (@/tmp/.X11-unix/X0), which our path read as unnamed. Three unix-socket kernel fixes later, the clients found the server.

The terminal opened and closed a second later. VTE turns on TIOCPKT packet mode on its pty — which we didn't implement — so it never opened its terminal. Once that worked, VTE's spawn called close_range(…, CLOSE_RANGE_CLOEXEC), and our kernel closed those descriptors instead of marking them close-on-exec, shredding VTE's error-report pipe mid-spawn and making every launch look like an instant exit.

Ctrl+C tore the whole desktop down. A VT-less Xorg never grabs the keyboard, so the kernel console kept cooking the same keystrokes X was reading — and a console Ctrl+C broadcast SIGINT at the entire session. The console now stays silent whenever an input stack has the keyboard open.

Next stop

Loading the entire filesystem into the heap on mount works today, but it won't scale as the desktop grows lazy, on-demand file loading is the obvious next step. After that: real GPU acceleration, and more of the apps that make a desktop feel like a desktop. The tree is on GitHub — patches welcome.