[Bug 2148725] Re: Green screen after KMS on Intel Jasper Lake (Beelink U59) – Kubuntu 26.04 daily

Bug Report Update Additional findings after further testing: Hardware Model: Beelink U59 mini PC GPU: Intel Jasper Lake UHD (i915) Systems Compared Two units of the same model were tested: U591 (failing unit) BIOS: JTKT001 Build date: 2022-05-05 Result: Fails to boot live session without nomodeset U592 (working unit) BIOS: JTKT001 Build date: 2022-03-09 Result: Boots live session normally Live USB Testing (Critical Observation) Using the same Kubuntu 26.04 live USB: U591: Hangs after plymouth-quit.service Black or green screen Requires nomodeset to boot (limited to 800×600) U592: Boots to desktop normally i915 loads successfully Full resolution available Cross-Distro Testing Debian live installer: fails on U591 Kubuntu 26.04 live: fails on U591 Kubuntu 26.04 live: works on U592 → Indicates issue is not distro-specific, but likely kernel/i915 related. Installed System Behavior (U591) Boots only with nomodeset Without it: System hangs during graphics initialization Suggests failure occurs during i915 KMS (Kernel Mode Setting) Working Reference System (U592) Running Live installer Kubuntu 26.04 LTS i915 loads successfully Wayland session works Resolution: 2048×1152 Windows Behavior Windows 11 runs normally on both units No display or GPU issues observed → Confirms hardware is functional Summary This appears to be a firmware-dependent i915 initialization issue: Reproducible on one unit (U591) Does not occur on another unit of the same model (U592) Occurs in live environment (not install-specific) Likely triggered during i915 KMS takeover from firmware PS, Congrats to Canonical for 26.04 LTS. -- You received this bug notification because you are subscribed to linux in Ubuntu. Matching subscriptions: Bgg, Bmail, Nb https://bugs.launchpad.net/bugs/2148725 Title: Green screen after KMS on Intel Jasper Lake (Beelink U59) – Kubuntu 26.04 daily Status in kwin package in Ubuntu: New Status in linux package in Ubuntu: New Status in plasma-desktop package in Ubuntu: New Bug description: Collected from Kubuntu 26.04 daily live session (booted with nomodeset due to graphics issue). System: Beelink U59 mini PC (Intel Jasper Lake, Intel UHD Graphics) Environment: Kubuntu 26.04 daily build (pre-release) Issue: System boots normally through early kernel messages. After the display switches to higher resolution (KMS activation), the screen turns solid green. Behavior: - Splash screen appears normally - Resolution changes (text becomes very small, likely 4K mode) - Several additional lines print - Screen turns completely green Workarounds tested: - nomodeset → boots successfully (no acceleration) - i915.enable_psr=0 → no change - i915.enable_dc=0 → no change - i915.enable_fbc=0 → no change - combinations of the above → no change This suggests a failure in i915 during KMS initialization. Reproducible: Yes, occurs consistently on every boot without nomodeset. Additional notes: The same Kubuntu 26.04 daily ISO boots and operates normally on another system at 1080p, indicating the issue is specific to this hardware (Beelink U59 / Intel Jasper Lake). System is stable in Windows 11 with 4K video playback, indicating hardware is functioning correctly. Ubuntu 7.0.0-14.14-generic 7.0.0 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/kwin/+bug/2148725/+subscriptions