Being able to read xorg.conf is not one my goals, nor achieving a bug-for-bug compatibility with Xorg - Xwayland with !901 (merged) allows to run a full X11 desktop, even the most legacy ones (I demoed it internally here using CDE from an XDMCP remote connection for the fun 😉).¹⁾

This is a how-to guide for running an X11 window manager or desktop environment in Xwayland on Slackware 15.0 and beyond.

At the time of writing (December 2023), this is a purely academic question for most – if not all – users. As both KDE Plasma and Xfce continue to move in the direction of Wayland, however, it is not impossible that full X servers become unavailable on Slackware in future years. This poses a dilemma from both a user and a software preservation perspective. Xwayland provides a way forward, if an imperfect one. The process of running an Xorg environment from inside a “rootfull” Xwayland session is straightforward:

• Choosing a Wayland compositor
  
• Configuration
  
• Running the Wayland compositor
  
• Starting the X11 environment on Xwayland
  

All outside packages mentioned here can be found on SlackBuilds Online.

The following considerations are important in choosing a Wayland compositor:

• Lightweight
• Stacking window management

• Able to suppress client-side decorations
• Compatible with wlroots for wlr-randr, a drop-in xrandr replacement.

This how-to will use labwc as an example. labwc is a lightweight, wlroots-based compositor with OpenBox-style configuration.

General configuration requirements are limited. It is only necessary to ensure that Xwayland-capable programs open under Xwayland rather than Wayland, and that startx does something productive.

Any program opening in Wayland mode will be managed by the Wayland compositor directly. This can result in the appearance of poorly-behaved windows with incorrect decoration and the non-appearance of system tray items. Place the following lines in /etc/environment²⁾ to control gtk and qt applications :

GDK_BACKEND=x11
QT_QPA_PLATFORM=xcb

For X keyboard maps other than US, it may also be necessary to specify a keymap here:

XKB_DEFAULT_LAYOUT=jp    # e.g.

Instructions for starting an X session should be contained in $HOME/.xinitrc because startx will launch Xwayland. xwmconfig can set up an xinitrc file for the preferred Xorg environment if need be.

Create an autostart file at $HOME/.config/labwc/autostart to launch an Xwayland server with startx:

#!/bin/sh

DISPLAY=:1 startx -- /usr/bin/Xwayland

This variant closes labwc after quitting the Xorg environment to return cleanly to tty or the display manager:

#!/bin/sh

DISPLAY=:1 startx -- /usr/bin/Xwayland &
wmpid=$!
wait $wmpid
pkill -x labwc

To stop labwc from decorating the Xwayland server window, write the following to a file at $HOME/.config/labwc/rc.xml:

<labwc_config>
  <core>
    <decoration>client</decoration>
  </core>
</labwc_config>

If auto-starting xset tends to fail, try adding a few seconds of sleep before startx.

These changes reflect post-15.0 Xwayland development:

• Rootfull Xwayland windows are no longer decorated, so rc.xml is unnecessary.
• The initial geometry of the Xwayland server must be specified. Replace the Xwayland line in the autostart script above with the following

DISPLAY=:1 startx – /usr/bin/Xwayland -fullscreen -geometry 1920×1200

Ideally, the geometry option will match the dimensions of the monitor. xrandr can change the resolution afterwards.

The Wayland compositor should be known to the display manager for Run Level 4 users, assuming that its package includes a desktop file. Run Level 3 users can run the Wayland compositor directly from the command line:

$ /usr/bin/labwc

Once the autostart script has started the X11 environment, the following commands can verify that the process worked:

$ pgrep Xorg
$ pgrep Xwayland

If there is at least one Xwayland process (may vary by Wayland compositor) and no Xorg process, feel free to take a screenshot (optional) and tell your friends (not advised).

The following caveats bear mentioning:

• Mouse pointer warping does not work. EdgeScroll in Fvwm is an example of an impacted feature.
• xrandr is non-functional in Xwayland versions before 22.1.3, and an extra program such as wlr-randr would be needed for screen management. Effectively, this restricts the choice of compositor to those based on wlroots.
• GPU memory usage is slightly higher relative to running an ordinary xserver.
• Wayland-only programs and any other program that runs in Wayland mode will be managed by the Wayland compositor rather than the X11 environment.
• Neither xinput nor synclient will work to turn off touchpads, for example.
• If an input device does not work in the chosen Wayland compositor, running an Xwayland server will not cause it to start working.
• xbacklight does not work; echoing values to /sys/class/backlight/*/brightness may be a workaround, depending on the system.
• If audio sharing fails, try using pipewire with wireplumber³⁾.

The above list is non-exhaustive.

• Xwayland(1)
• labwc(1)
• xserver, Issue #1173: Xwayland: Improve rootfull mode for legacy X11 environments