X11 Session for X-Plane
The recommended setup for X-Plane on Linux. In an X11 session, X-Plane communicates directly with the X server — no translation layer, no overhead.
What Happens
Everything speaks the same protocol. X-Plane's X11 calls go straight to the X server, which passes them to the GPU. No compositor translation, no extra frame copies.
Check Your Current Session
If the output is x11, you are already in an X11 session. No changes needed.
If the output is wayland, follow the steps below to switch.
Switch to X11
At the Login Screen
The session type is selected before logging in. Look for a gear icon or session menu, usually in the bottom corner.
GDM (GNOME)
- Click your username
- Before entering your password, click the gear icon (bottom right)
- Select "GNOME on Xorg"
SDDM (KDE)
- At the login screen, look for the session selector (bottom left)
- Select "Plasma (X11)"
This selection persists until you change it again. You do not need to re-select it on every login.
Make X11 Permanent (Optional)
If you want to prevent Wayland sessions entirely, you can disable Wayland at the display manager level.
GDM (GNOME)
After saving, restart GDM or reboot. The login screen will only offer X11 sessions.
SDDM (KDE)
SDDM does not use Wayland for the login screen on Debian. Selecting "Plasma (X11)" at the session menu is sufficient.
Compositor Bypass
In an X11 session, fullscreen applications can bypass the compositor entirely. This eliminates one frame of latency that the compositor would otherwise add.
KDE Plasma
KDE suspends compositing when a fullscreen application requests it. The default setting "Allow applications to block compositing" handles this. No manual configuration needed.
To verify, run X-Plane in fullscreen and check:
Output false means the compositor is bypassed — X-Plane renders directly to the screen.
GNOME
Mutter (GNOME's compositor) does not support full compositor bypass, but performs an optimization called direct scanout for fullscreen applications. This avoids the GPU composition step while the compositor remains active.
Desktop Entry
An optional .desktop file ensures X-Plane always starts with the X11 backend, even if your session type changes later.
# ~/.local/share/applications/x-plane-12.desktop
[Desktop Entry]
Name=X-Plane 12
Exec=env SDL_VIDEODRIVER=x11 GDK_BACKEND=x11 /path/to/X-Plane-x86_64
Type=Application
Categories=Game;Simulation;
Comment=X-Plane 12 Flight Simulator (X11)
Replace /path/to/ with the actual path to your X-Plane installation.
SDL_VIDEODRIVER=x11 tells SDL2 to use the X11 backend. GDK_BACKEND=x11 ensures the identity login browser also uses X11. X-Plane sets this internally since version 12.1.3, but specifying it in the desktop entry guarantees it for all launch methods.
Advantages
- No latency overhead — direct X11 path, no XWayland translation
- Reliable fullscreen — compositor bypass works, no edge cases
- Multi-monitor — X-Plane fullscreen across monitors works without issues
- Identity login — no workarounds needed
- Proven path — X-Plane has used X11 on Linux since its first release
Limitations
- Single refresh rate — all monitors share the same refresh rate under X11. If you have a 144 Hz and a 60 Hz monitor, both run at 60 Hz
- Limited VRR per monitor — Variable Refresh Rate support exists but per-monitor VRR is problematic under X11
- Desktop security — X11 allows applications to read each other's input (no isolation between windows)
These limitations affect the desktop experience, not X-Plane itself. For a dedicated flight sim setup, they are rarely relevant.
Returning to Wayland
If you want to switch back to a Wayland session later, select "GNOME" or "Plasma (Wayland)" at the login screen. If you disabled Wayland permanently via daemon.conf, re-enable it first:
See Display Server Overview for latency measurements and GPU recommendations.