https://bugs.kde.org/show_bug.cgi?id=504102
Bug ID: 504102
Summary: Wayland session fails to load on boot with NVIDIA + 4
monitors; KWin aborts with assertion failure
Classification: Plasma
Product: kwin
Version: 6.3.5
Platform: NixOS
OS: Linux
Status: REPORTED
Severity: major
Priority: NOR
Component: platform-drm
Assignee: kwin-bugs-n...@kde.org
Reporter: frank.wehrmann...@gmail.com
Target Milestone: ---
Created attachment 181213
--> https://bugs.kde.org/attachment.cgi?id=181213&action=edit
Relevant crash log
### Summary
Wayland session fails to start with KWin 6.3.5 on NixOS using NVIDIA GPU and
quad-display setup (All GPU outputs populated). Session aborts early when 4
monitors are connected via DisplayPort and HDMI to an RTX 4090.
### Steps to Reproduce
1. Boot into a Wayland session with NVIDIA RTX 4090
2. Have four monitors connected via DisplayPort and HDMI
3. Attempt to start a Wayland session
### Observed Result
```
kwin_wayland: Invalid framebuffer status:
"GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT"
kwin_wayland: 0x502: GL_INVALID_OPERATION error generated. <image> and <target>
are incompatible
kwin_wayland_drm: Checking test buffer failed!
```
These messages repeat continuously until the system becomes unresponsive. A
hard reboot is required.
No desktop appears, session fails.
### Expected Result
KWin should initialize the session and handle display configuration.
### Hardware
- **GPU**: NVIDIA RTX 4090 (proprietary driver)
- **CPU**: AMD Ryzen 7 5800X3D
- **Motherboard**: B550M AORUS PRO-P
- **Displays**: Four monitors connected:
- 2× 1920×1200 @ 60Hz (DisplayPort)
- 1× 1920×1080 @ 60Hz (HDMI)
- 1× 2560×1440 @ 360Hz (DisplayPort)
### Software/OS Versions
- **Operating System**: NixOS 25.05 (Warbler) – `25.05pre797896.d89fc19e405c`
(Unstable Channel)
- **Kernel Version**: 6.12.28 (64-bit)
- **KDE Plasma Version**: 6.3.5
- **KDE Frameworks Version**: 6.14.0
- **Qt Version**: 6.9.0
- **Graphics Platform**: Wayland (default session)
- **Driver Version**: 570.144 (proprietary)
- **CUDA Version**: 12.8
- **Vulkan Support**: Verified and functional
- **GL Support**: Verified via `glxinfo`
- **nvidia-smi Output**: Shows active workloads and correct memory usage
### Reproducibility
100% reproducible on boot with four monitors connected.
### Notes
- This issue does not occur with X11 or three-monitor Wayland sessions.
- All hardware and driver components (NVIDIA driver, CUDA, Vulkan stack) are
correctly installed and functioning in X11 sessions and gaming workloads.
- The system uses the proprietary NVIDIA driver (`hardware.nvidia.open =
false`) with modesetting enabled, VRR and G-SYNC environment variables
exported, and 32-bit support enabled for compatibility.
- `boot.kernelParams` includes `nvidia-drm.modeset=1`.
- This issue has been reproduced across multiple distributions, including
Nobara, Debian Unstable, and openSUSE Tumbleweed, suggesting it is not specific
to NixOS.
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