Public bug reported:
Summary:
After automatic update from linux-firmware version .17 to .19 on October 17,
2025, Ubuntu 24.04 displays black screen on login when using dual LG ULTRAFINE
4K monitors with 200% fractional scaling on Wayland. The issue specifically
occurs when GNOME/GDM attempts to initialize displays at 200% scaling during
boot.
Hardware:
- CPU: AMD Ryzen 16-core
- GPU: AMD (integrated graphics)
- Monitors: 2x LG ULTRAFINE 4K (3840x2160) via DisplayPort
- Display Server: Wayland
- Desktop: GNOME
Steps to Reproduce:
1. Have dual 4K monitors configured at 200% fractional scaling
2. Update linux-firmware from .17 to .19
3. Save display configuration at 200% scaling
4. Reboot
5. Attempt to login
Expected Result:
Desktop should load normally with both monitors displaying correctly at 200%
scaling
Actual Result:
Black screen after login when monitors.xml contains 200% scaling configuration
Key Diagnostic Findings:
- Deleting ~/.config/monitors.xml allows login at 100% default scaling
- Changing to 200% scaling AFTER login works perfectly
- Problem only occurs when GDM/GNOME loads 200% scaling during boot
initialization
- Rebooting after setting 200% recreates the black screen issue
- This is a boot-time initialization bug, not a runtime scaling bug
Workaround:
Deleting ~/.config/monitors.xml before each login allows access, but requires
manual reconfiguration to 200% each session (unsustainable for daily use)
Fix:
Downgrading to linux-firmware=20240318.git3b128b60-0ubuntu2.17 resolves the
issue completely. All scaling levels work correctly with firmware .17.
Additional Information:
- Wayland is required for this hardware setup (X11 has display issues with dual
4K monitors even on firmware .17)
- Single monitor configuration was not tested
- Issue appeared immediately after firmware update on Oct 17, 2025
- Firmware .17 works perfectly with Wayland + dual 4K + 200% scaling at all
times (boot and runtime)
- Bug is specific to boot-time display initialization with 200% fractional
scaling in firmware .19
System Information:
- Ubuntu Version: 24.04.3 LTS
- linux-firmware installed: 20240318.git3b128b60-0ubuntu2.17 (working -
currently held)
- linux-firmware candidate: 20240318.git3b128b60-0ubuntu2.19 (broken - causes
black screen)
ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: linux-firmware 20240318.git3b128b60-0ubuntu2.17
ProcVersionSignature: Ubuntu 6.14.0-33.33~24.04.1-generic 6.14.11
Uname: Linux 6.14.0-33-generic x86_64
ApportVersion: 2.28.1-0ubuntu3.8
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC1: joe 2802 F.... wireplumber
/dev/snd/controlC0: joe 2802 F.... wireplumber
/dev/snd/seq: joe 2797 F.... pipewire
CRDA: N/A
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Sat Oct 18 10:25:24 2025
Dependencies: firmware-sof-signed 2023.12.1-1ubuntu1.10
InstallationDate: Installed on 2025-10-15 (3 days ago)
InstallationMedia: Ubuntu 24.04.3 LTS "Noble Numbat" - Release amd64
(20250805.1)
MachineType: ASUS System Product Name
ProcEnviron:
LANG=en_US.UTF-8
PATH=(custom, no user)
SHELL=/bin/bash
TERM=xterm-256color
XDG_RUNTIME_DIR=<set>
ProcFB: 0 amdgpudrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-6.14.0-33-generic
root=UUID=50126da2-dd87-4955-8708-1ecb4482ba78 ro quiet splash
RelatedPackageVersions:
linux-restricted-modules-6.14.0-33-generic N/A
linux-backports-modules-6.14.0-33-generic N/A
linux-firmware 20240318.git3b128b60-0ubuntu2.17
RfKill:
0: phy0: Wireless LAN
Soft blocked: no
Hard blocked: no
SourcePackage: linux-firmware
UpgradeStatus: No upgrade log present (probably fresh install)
acpidump: Error: command ['pkexec', '/usr/share/apport/dump_acpi_tables.py']
failed with exit code 126: Error executing command as another user: Request
dismissed
dmi.bios.date: 07/14/2025
dmi.bios.release: 10.78
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 1078
dmi.board.asset.tag: Default string
dmi.board.name: ROG STRIX B850-A GAMING WIFI
dmi.board.vendor: ASUSTeK COMPUTER INC.
dmi.board.version: Rev 1.xx
dmi.chassis.asset.tag: Default string
dmi.chassis.type: 3
dmi.chassis.vendor: Default string
dmi.chassis.version: Default string
dmi.modalias:
dmi:bvnAmericanMegatrendsInc.:bvr1078:bd07/14/2025:br10.78:svnASUS:pnSystemProductName:pvrSystemVersion:rvnASUSTeKCOMPUTERINC.:rnROGSTRIXB850-AGAMINGWIFI:rvrRev1.xx:cvnDefaultstring:ct3:cvrDefaultstring:skuSKU:
dmi.product.family: To be filled by O.E.M.
dmi.product.name: System Product Name
dmi.product.sku: SKU
dmi.product.version: System Version
dmi.sys.vendor: ASUS
** Affects: linux-firmware (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug noble wayland-session
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https://bugs.launchpad.net/bugs/2128883
Title:
linux-firmware 20240318.git3b128b60-0ubuntu2.19 causes black screen on
login with dual 4K monitors at 200% scaling on Wayland (AMD GPU)
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