Fractional scaling on 4K monitor exceeds GL_MAX_TEXTURE_SIZE on Raspberry Pi 5

[sailoz]

Hello
I'd like to report a bug.
Can you please take a look, and help solve the issue?

• Hardware: Raspberry Pi 5 (8GB), 4K Monitor HP 27f, 1080p Monitor IO-data LCD-MF221X .
  HP_27f_4k.txt
  LCD-MF221X_1080p.txt

• OS & Drivers: Arch Linux ARM with Mesa V3D driver.
  OS : https://github.com/manjaro-arm/rpi4-images/releases/download/20250721/Manjaro-ARM-minimal-rpi4-20250721.img.xz
  Setup: https://github.com/basecamp/omarchy

  Installed versions:

  hyprctl-systeminfo.txt

  extra/hyprland 0.49.0-3 (46.7 MiB 60.9 MiB) (Installed) https://archlinuxarm.org/packages/aarch64/hyprland
  extra/sway 1:1.11-1 (4.9 MiB 5.9 MiB) (Installed) https://archlinuxarm.org/packages/aarch64/sway

*Behavior: "Hyprland works perfectly on a 1080p monitor. On a 4K monitor with 4K resolution, the renderer fails, resulting in a black screen where the background (with or without using swaybg), and Waybar are not visible, but waybar area is there, no fonts, icons, and mouse can hover.

Other applications works fine, including Gnome Calcultor, Alacritty, Brave Browser, etc. 

• Likely Root Cause: "Hyprland MESA_DEBUG=all logs show the renderer is failing with the error: Mesa: error: GL_INVALID_VALUE in glTexImage2D(invalid width=4608...)."
  Hyprland_mesa_debug.log

  Sway in 4k has 0 byte MESA_DEBUG log.
  Hyprland in 1080p has 0 byte MESA_DEBUG log.

• Proof:
  "This is because the requested width of 4608 exceeds the Pi's hardware limit, which can be confirmed with glxinfo -l | grep GL_MAX_TEXTURE_SIZE (it reports 4096)."
  glxinfo.log

*Comparative Analysis: "The bug is possibly specific to Hyprland, as a simpler wlroots compositor (Sway) works correctly on the same 4K monitor with 4K resolution."

Thank you for taking time to look this report.

[vaxerski]

What's the scale factor? Maybe try setting it to 1 or 2. Under 1.5, for example, buffers get bigger than the pixel size.

[sailoz]

Thank you for taking time to lookiing at this.

Scale 1 and 2 work well.
Scale 1.333333, 1.5, 1.666667, show no background and black waybar.

I also tested 2560x1440@59.95Hz, and works fine but feels a bit blur.

I was using 1.666667.

If possible, I'd like to use fractional scaling to see more workspace, as 1 is too small prints, and 2 is less informatoin to display at once.

What would be next course of action we could take?

Thank you.

[vaxerski]

not possible due to how wayland scaling works