drm: Overlay plane doesn't support any formats >= 8888

[Viruzaum]

Is there an existing issue for this?

• I have searched the existing issues

Are you using any gamescope patches or a forked version of gamescope?

• The issue occurs on upstream gamescope without any modifications

Current Behavior

trying to start gamescope with drm gives the error: Overlay plane doesn't support any formats >= 8888

Steps To Reproduce

1. Launch gamescope -- vkcube

Hardware information

- Distro: NixOS 25.05 (Warbler)
- CPU: dual core Intel Core i5-3337U
- GPU: Intel(R) HD Graphics 4000
- Driver Version: Mesa 24.3.4

Software information

- Desktop environment: COSMIC
- Session type: wayland
- Gamescope version: gamescope version 3.16.1 (gcc 14.2.1)
- Gamescope launch command(s): `gamescope -- vkcube`

Which gamescope backends have the issue you are reporting?

• Wayland (default for nested gamescope)
• DRM (default for embedded gamescope, i.e. gamescope-session)
• SDL
• OpenVR

Logging, screenshots, or anything else

log.txt