Wayland desktop (experimental)

Ixolo has a small graphical desktop: the LXQt panel and a terminal, drawn by Qt 6 on a native Wayland compositor, wlcompd. Everything is rendered in software into the UEFI framebuffer. There is no X11 and no GPU driver.

How it fits together

 qterminal   lxqt-panel   lxqt-config ...      Qt 6 apps (static binaries)
      \           |           /                 Qt raster engine, no OpenGL
       \          |          /
        Wayland protocol over a Unix socket; pixels in POSIX shared memory
                  |
              wlcompd                           compositor and window manager
               /     \
        /dev/fb0      /dev/kbdmux, /dev/mouse   pixman + FreeType
           |               |
       fb driver      input server <- PS/2 keyboard and mouse (pckbd)
           |
     UEFI GOP framebuffer

/dev/fb0: the fb driver exposes the linear framebuffer that the UEFI firmware’s Graphics Output Protocol (GOP) set up at boot. That is why the desktop needs UEFI: a BIOS boot has no framebuffer for it.
wlcompd: a Wayland compositor written for Ixolo. It is in the base system. It composites with pixman, draws title bars with FreeType, and implements xdg-shell, wlr-layer-shell (for the panel), wlr-foreign-toplevel-management (for the task bar), ext-workspace (four virtual desktops) and server-side decorations.
Qt 6 (6.11.1), with its raster paint engine. Clients draw into wl_shm buffers, which are POSIX shared memory files on the tmpfs at /var/shm.
LXQt 2.4: lxqt-session, lxqt-panel, qterminal, lxqt-config, lxqt-about, with GLib 2.80 and D-Bus 1.16 underneath.

Every Qt and LXQt program is linked statically. A dynamically linked Qt crashed before main(), in thread-local storage handling of the dynamic linker, so the port avoids it. The design study behind all this is Running Wayland.

Requirements

	Needed
Firmware	UEFI with GOP. In QEMU: OVMF.
Memory	[RAM_DESKTOP]
Keyboard and mouse	PS/2 (QEMU’s default devices). USB keyboards and mice are not supported.
Graphics	Any card the firmware can drive with GOP. No GPU acceleration is used.
Image	One built with the desktop (see below).

Getting an image with the desktop

The CI ISO and a default build do not contain LXQt. Check for it with:

ls /usr/bin/lxqt-session

To build an image with it, you need a full build of the system first, as in building from source. Then releasetools/build-desktop.sh fetches the pinned upstream sources, patches them, cross-compiles them in dependency order and installs them into the build’s DESTDIR. MKDESKTOP=yes lays the result over the ISO:

DESTDIR=$PWD/obj.amd64/destdir.amd64 \
TOOLDIR=$PWD/obj.amd64/tooldir.Linux-x86_64 \
QT_HOST_PATH=/usr \
  sh releasetools/build-desktop.sh
MKDESKTOP=yes UEFI=yes OBJ=obj.amd64 CREATE_IMAGE_ONLY=1 IMG=ixolo-[VERSION]-amd64.iso \
  bash releasetools/amd64_cdimage.sh

The host needs meson, ninja, cmake, curl, patch, pkg-config, sha256sum and a host Qt of exactly the same version (6.11.1), pointed to by QT_HOST_PATH. The manifest of sources ships with sha256 = TOFILL placeholders, and the script refuses to build until you record the checksums with sh releasetools/build-desktop.sh checksums. All the details, including how to put the desktop in the installation sets instead of overlaying the ISO, are in building the desktop.

Starting it

Boot under UEFI. In QEMU, with OVMF’s code and variable files (the paths depend on your distribution):

cp /usr/share/OVMF/OVMF_VARS_4M.fd my_vars.fd
qemu-system-x86_64 -enable-kvm -cpu host -m 2G -smp 2 -vga std \
  -drive if=pflash,unit=0,format=raw,readonly=on,file=/usr/share/OVMF/OVMF_CODE_4M.fd \
  -drive if=pflash,unit=1,format=raw,file=my_vars.fd \
  -cdrom ixolo-[VERSION]-amd64.iso

startlxqt

startlxqt does everything: it starts the fb driver, starts wlcompd and waits for its socket, starts a D-Bus session bus, and runs lxqt-session, which brings up the panel. It keeps its sockets and logs in $XDG_RUNTIME_DIR, by default /tmp/runtime-<uid>, mode 0700.

Windows get a title bar drawn by the compositor, with a close box on the right and a resize grip in the bottom-right corner. Open a terminal from the panel’s menu.

To start the compositor at boot instead, set wlcompd=YES in /etc/rc.conf. That only starts wlcompd, not the LXQt session. It takes over the framebuffer and the keyboard, so the framebuffer becomes the main console; the serial console keeps working. Do not enable fbcompd at the same time.

What works and what does not

Works:

The panel, docked at the top: menu, quick launch, task bar, the pager with four virtual desktops, “show desktop” and a world clock.
qterminal, with a shell on a pseudo-terminal.
Moving, resizing and closing windows; menus and pop-ups.
The DejaVu fonts shipped in the base system.

lxqt-config and lxqt-about are built too, but have had less testing.

Does not work, or is not there:

Copy and paste between programs. The compositor records the clipboard owner but does not pass the data on to other programs yet.
Panel plugins outside the built-in set. A static binary cannot load plugins at run time, so only plugins compiled into the panel exist. The CPU, network, volume, sensors, keyboard-layout and system-tray plugins need libraries Ixolo does not have.
Global keyboard shortcuts (lxqt-globalkeys): Wayland gives a client no way to grab other clients’ keys, and wlcompd has no protocol for it.
X11 programs: there is no X server and no XWayland.
OpenGL, hardware acceleration, video playback.
USB keyboards and mice, and keyboard layouts other than US.
A file manager, a web browser and other applications: only the components listed above are built.

Reporting desktop bugs

Collect these before you report:

$XDG_RUNTIME_DIR/wlcompd.log and $XDG_RUNTIME_DIR/lxqt-session.log (by default in /tmp/runtime-0 when you run as root);
how you built the image: the devel commit, and whether it was overlaid with MKDESKTOP=yes or put in the sets;
the QEMU command line or the hardware, and the firmware;
what you did, what you expected and what happened. A screenshot helps.

Then report it at https://github.com/davmont/minix/issues. If it is a crash of a system service (for example fb or the input server), say so: those are bugs in Ixolo, not in LXQt.