XLibre crashes when changing resolution via xrandr in QEMU/KVM VM

### Select the version

25.1.X

### Describe your issue

When running XLibre inside a QEMU/KVM virtual machine, attempting to change the display resolution using `xrandr` causes the X server to terminate immediately and the graphical session exits back to the TTY.

The issue occurs regardless of the selected virtual GPU model or whether 3D acceleration is enabled or disabled.

If the resolution remains at the default value provided at session start (1280×800), the display functions normally.

Environment

Guest OS:

Gentoo Linux x86_64  
Kernel: 6.18.12-gentoo  
Packages: ~861  
Shell: zsh 5.9

Virtualization:

QEMU/KVM  
Machine type: Q35  
Display protocol: SPICE  
Host CPU: Intel i5-6300U (host-passthrough)

Guest hardware presented to VM:

GPU: RedHat Virtio GPU  
Display: Virtual-1  
Resolution (default): 1280x800

XLibre pkg:
[ebuild   R   ~] x11-base/xlibre-server-25.1.2:0/25.1.2::xlibre  USE="elogind glx glx-dri udev xinerama xorg -debug -minimal -seatd (-selinux) -suid -systemd -test -unwind -xcsecurity -xephyr -xfbdev -xnest -xvfb*" 0 KiB

VM configuration is attached (`qemu-machine-setup.log`).

This issue is related to the Gentoo port report: https://github.com/X11Libre/ports-gentoo/issues/114


### Steps to reproduce

### Steps to reproduce

# Reproduction Steps

1. Boot the virtual machine.
    
2. Start XLibre normally.
    
3. Run:
    

xrandr --output Virtual-1 --mode 1920x1080

---

# Observed Behaviour

The X server terminates immediately and the graphical session exits back to the TTY.

Client output from `xrandr`:

X connection to :0 broken (explicit kill or server shutdown).

### What did you expect?

<h1 data-heading="Expected Behaviour">Expected Behaviour</h1>
<p>The resolution should change normally via the RandR interface without terminating the X server.</p>
<hr>
<h1 data-heading="xrandr Output">xrandr Output</h1>
<p>Example display modes reported:</p>
<p>Screen 0: minimum 320 x 200, current 1280 x 800, maximum 8192 x 8192<br>
Virtual-1 connected primary 1280x800+0+0  </p>
<p>1280x800 74.99*<br>
1920x1080 60.00<br>
3840x2160 60.00<br>
4096x2160 50.00<br>
5120x2160 50.00<br>
...</p>
<p>Full verbose output is attached.</p>
<hr>
<h1 data-heading="GPU / Video Model Testing">GPU / Video Model Testing</h1>
<p>The behaviour was tested across multiple QEMU virtual GPU models:</p>

Video Model | Result
-- | --
Virtio GPU (3D disabled) | X server crashes when resolution is changed
Virtio GPU (3D enabled) | Same behaviour
QXL | Same behaviour
Bochs | Same behaviour
Ramfb | Same behaviour
VGA | XLibre does not start (only works until GRUB)


<p>Therefore the issue does not appear to be tied to a specific virtual GPU implementation.</p>

### Additional Information

# Additional Notes

- The display functions normally as long as the resolution is not changed.
    
- The issue occurs for **any resolution change**, not a specific mode.
    
- Kernel and DRM logs show no obvious GPU driver failure preceding the X server exit.
    

---

# Attached Logs

The following logs are attached for investigation:

loaded-modules.log  
system.log  
vm-gpu-info.log  
qemu-machine-setup.log  
  
xlibre-full.log  
xlibre-errors.log  
xlibre-last-session.log  
xlibre-last-ext-session.log  
  
xlibre-dmesg.log  
xlibre-gpu-dmesg.log  
  
xrandr-output.log  
xrandr-verbose.log  
xrandr-crash-session.log  
xrandr-modset-crash-session.log

## Additional Diagnostics

Two additional diagnostic files are included to provide further visibility into the graphics stack and kernel display configuration at the time of testing.

### DRM State Dump

`drm-state.log`

This file was captured from the kernel DRM debug interface:

cat /sys/kernel/debug/dri/0/state

This reflects the **kernel display configuration while XLibre is running prior to triggering the crash**.

---

### PCI GPU Driver Binding

`pci-gpu-driver.log`

This file confirms which kernel driver is bound to the virtual GPU device while the driver stack is being used by the virtual machine during testing.

---

# Notes for Maintainers

The issue appears to occur during RandR mode switching. The `xrandr` client loses its connection because the X server exits rather than returning a mode configuration error.

[drm-state.log](https://github.com/user-attachments/files/25826827/drm-state.log)
[loaded-modules.log](https://github.com/user-attachments/files/25826826/loaded-modules.log)
[pci-gpu-driver.log](https://github.com/user-attachments/files/25826830/pci-gpu-driver.log)
[qemu-machine-setup.log](https://github.com/user-attachments/files/25826831/qemu-machine-setup.log)
[system.log](https://github.com/user-attachments/files/25826828/system.log)
[vm-gpu-info.log](https://github.com/user-attachments/files/25826829/vm-gpu-info.log)
[xlibre-dmesg.log](https://github.com/user-attachments/files/25826832/xlibre-dmesg.log)
[xlibre-driver.log](https://github.com/user-attachments/files/25826836/xlibre-driver.log)
[xlibre-errors.log](https://github.com/user-attachments/files/25826837/xlibre-errors.log)
[xlibre-full.log](https://github.com/user-attachments/files/25826839/xlibre-full.log)
[xlibre-gpu-dmesg.log](https://github.com/user-attachments/files/25826838/xlibre-gpu-dmesg.log)
[xlibre-last-ext-session.log](https://github.com/user-attachments/files/25826833/xlibre-last-ext-session.log)
[xlibre-last-session.log](https://github.com/user-attachments/files/25826842/xlibre-last-session.log)
[xrandr-crash-session.log](https://github.com/user-attachments/files/25826834/xrandr-crash-session.log)
[xrandr-modset-crash-session.log](https://github.com/user-attachments/files/25826841/xrandr-modset-crash-session.log)
[xrandr-output.log](https://github.com/user-attachments/files/25826835/xrandr-output.log)
[xrandr-verbose.log](https://github.com/user-attachments/files/25826840/xrandr-verbose.log)

### Extra fields

- [x] I have checked the existing [issues](https://github.com/X11Libre/xserver/issues)
- [x] I have read the [Contributing Guidelines](https://github.com/X11Libre/xserver/blob/master/CONTRIBUTING.md)
- [ ] I'd like to work on this issue

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XLibre crashes when changing resolution via xrandr in QEMU/KVM VM #2107

Select the version

Describe your issue

Steps to reproduce

Steps to reproduce

Reproduction Steps

Observed Behaviour

What did you expect?

Expected Behaviour

xrandr Output

GPU / Video Model Testing

Additional Information

Additional Notes

Attached Logs

Additional Diagnostics

DRM State Dump

PCI GPU Driver Binding

Notes for Maintainers

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Video Model	Result
Virtio GPU (3D disabled)	X server crashes when resolution is changed
Virtio GPU (3D enabled)	Same behaviour
QXL	Same behaviour
Bochs	Same behaviour
Ramfb	Same behaviour
VGA	XLibre does not start (only works until GRUB)

XLibre crashes when changing resolution via xrandr in QEMU/KVM VM #2107

Description

Select the version

Describe your issue

Steps to reproduce

Steps to reproduce

Reproduction Steps

Observed Behaviour

What did you expect?

Expected Behaviour

xrandr Output

GPU / Video Model Testing

Additional Information

Additional Notes

Attached Logs

Additional Diagnostics

DRM State Dump

PCI GPU Driver Binding

Notes for Maintainers

Extra fields

Metadata

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

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