Category: Troubleshooting

The Problem

After updating Ubuntu to the latest version ( Ubuntu 25.10 | October 2025), the GDM (GNOME Display Manager) login screen completely stopped loading. The system would boot normally but never display the graphical login interface.

System Configuration

• OS: Ubuntu 25.10 (updated October 2025)
• Kernel: Linux 6.14.0-32-generic
• GPU Setup: Dual GPU system – NVIDIA GeForce RTX 3050 Mobile (Driver 580.95.05) | AMD Radeon Vega (integrated)
• Display Manager: GDM3
• Desktop Environment: GNOME 49

Initial Symptoms

When attempting to access the GUI:

• Black screen with no login prompt
• GDM service appeared to be running (systemctl status gdm showed “active”)
• Could access system via TTY (Ctrl+Alt+F2)
• No obvious error messages in initial logs

Investigation Process

Step 1: Check GDM Service Status

sudo systemctl status gdm3

Finding: GDM was active but logs showed repeated failures:

Gdm: GdmDisplay: Session never registered, failing
Gdm: GdmLocalDisplayFactory: maximum number of X display failures reached: check X server log for errors

The greeter was launching but immediately crashing in a loop.

Step 2: Check GNOME Shell Logs

journalctl -b | grep -i "gnome-shell\|mutter\|wayland"

Critical Finding: Found the root cause error repeated multiple times:

gnome-shell: symbol lookup error: /lib/x86_64-linux-gnu/libmutter-17.so.0: undefined symbol: wl_fixes_interface

This indicated a library dependency issue – GNOME Shell was crashing because it couldn’t find a required symbol in the Wayland library.

Step 3: Analyze Library Dependencies

Checked which Wayland library GNOME Shell was using:

ldd /usr/bin/gnome-shell | grep -i wayland

Output:

libwayland-server.so.0 => /opt/amdgpu/lib/x86_64-linux-gnu/libwayland-server.so.0

Problem Identified: GNOME Shell was loading the AMD GPU driver’s old Wayland library instead of the system library.

Step 4: Compare Library Versions

dpkg -l | grep -i "libwayland\|libmutter\|gnome-shell"

Findings:

• System Wayland libraries: 1.24.0 (correct, up-to-date)
• AMD GPU Wayland libraries: 1.23.0 (outdated, from /opt/amdgpu/lib/)
• GNOME Shell: 49.0
• Mutter: 49.0 (libmutter-17)

The October 2025 Ubuntu 25.04 update upgraded GNOME/Mutter to version 49 (Mutter 17), which requires Wayland 1.24.0 with the wl_fixes_interface symbol. The old AMD 1.23.0 libraries don’t have this symbol.

Step 5: Find the Configuration Causing This

cat /etc/ld.so.conf.d/20-amdgpu.conf

Content:

/opt/amdgpu/lib/x86_64-linux-gnu
/opt/amdgpu/lib/i386-linux-gnu

This configuration file was forcing the dynamic linker to prioritize AMD’s outdated libraries over the system libraries.

Root Cause Analysis

The issue was caused by a library path priority conflict:

1. The October 2025 Ubuntu update upgraded GNOME Shell to version 49, which uses Mutter 17
2. Mutter 17 requires Wayland 1.24.0 with new symbols including wl_fixes_interface
3. The system had AMD GPU proprietary drivers installed from /opt/amdgpu/
4. The file /etc/ld.so.conf.d/20-amdgpu.conf configured the dynamic linker to check AMD’s library paths first
5. AMD’s libraries included an outdated Wayland 1.23.0 that lacked the required symbols
6. GNOME Shell loaded the incompatible AMD Wayland library and crashed on startup
7. GDM repeatedly tried to launch the greeter, resulting in a crash loop

The Solution

The fix involved disabling the AMD library path configuration to allow the system to use the correct Wayland libraries:

Step 1: Disable AMD Library Path Configuration

sudo mv /etc/ld.so.conf.d/20-amdgpu.conf /etc/ld.so.conf.d/20-amdgpu.conf.disabled

This renames the file so the dynamic linker ignores it while preserving it for potential future use.

Step 2: Rebuild Dynamic Linker Cache

sudo ldconfig

This rebuilds the library cache without the AMD paths, forcing the system to use standard library locations.

Step 3: Restart GDM

sudo systemctl restart gdm

Restarts the display manager with the corrected library configuration.

Verification

After restarting GDM, verify GNOME Shell is running:

ps aux | grep gnome-shell | grep -v grep

Expected output should show gnome-shell running as the gdm-greeter user.

Results

After applying the fix:

• GDM login screen loads successfully
• GNOME Shell runs without crashes
• Wayland session works correctly
• System uses proper Wayland 1.24.0 libraries from /lib/x86_64-linux-gnu/

Why This Happened

This is a classic dependency version conflict that emerged during a major system update:

1. Proprietary driver packages often bundle their own versions of system libraries to ensure compatibility
2. Library path configuration (/etc/ld.so.conf.d/) determines which library versions get loaded
3. Major version updates can introduce new API requirements that old bundled libraries don’t support
4. The AMD driver package wasn’t updated in sync with GNOME, leaving incompatible libraries in place

If you’re using an AMD Ryzen processor like the Ryzen 7 4800H on Ubuntu ( which i currently have on my personal laptop ), you might have experienced severe CPU throttling after resuming from suspend mode. This issue is particularly noticeable during CPU-intensive tasks when the processor is stuck at a much lower frequency, typically around 1.4 GHz, even though it is capable of reaching up to 4.3 GHz.

Most users are not even aware of this throttling issue because they are not actively monitoring the CPU frequency. If you are experiencing severe lag, poor responsiveness, and overall slowness after resuming from suspend, these symptoms are the result of your CPU being locked to a lower frequency, which dramatically impacts the performance of course.

This solution should work on other related AMD Ryzen processors as well, including models from the Ryzen 4000, 5000, and even 7000 series. The root cause is linked to ACPI (Advanced Configuration and Power Interface) limitations imposed after suspend, which restrict the processor’s max frequency.

Diagnosing the Problem

First, let’s confirm the issue by running the following commands:

# Check CPU model
lscpu | grep 'Model name'

# Check current CPU frequencies
cat /proc/cpuinfo | grep 'cpu MHz'

# Check CPU governor status
cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor | sort | uniq

If you notice the frequencies are stuck below the max potential, the next step is to verify the imposed limits:

# Max frequency limit
cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq

# Hardware max frequency
cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq

# BIOS imposed limit
cat /sys/devices/system/cpu/cpu0/cpufreq/bios_limit

If your BIOS limit is lower than the hardware max frequency, you are experiencing ACPI throttling.

Implementing the Fix

To resolve this, follow the steps below:

Step 1: Create a Fix Script

Create a shell script to override the BIOS limitations:

#!/bin/bash
# Fix CPU frequency scaling after suspend

# Get the maximum hardware frequency
MAX_FREQ=$(cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq)

# Override BIOS limit if it exists
if [ -f /sys/devices/system/cpu/cpu0/cpufreq/bios_limit ]; then
    echo "BIOS limit detected, attempting to override..."
    echo $MAX_FREQ | sudo tee /sys/devices/system/cpu/cpu0/cpufreq/bios_limit > /dev/null || true
fi

# Set maximum frequency for all CPUs
for cpu in /sys/devices/system/cpu/cpu*/cpufreq/scaling_max_freq; do
    echo $MAX_FREQ | sudo tee $cpu > /dev/null
done

# Set performance governor for better scaling
for cpu in /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor; do
    echo performance | sudo tee $cpu > /dev/null
done

echo "CPU frequency scaling fixed. Max frequency set to $MAX_FREQ Hz with performance governor."

Make the script executable:

chmod +x ~/cpu_frequency_fix.sh

Step 2: Automate the Fix with Systemd

To make the fix persistent after every suspend cycle, create a systemd service:

sudo nano /etc/systemd/system/cpu_frequency_fix.service

Paste the following configuration:

[Unit]
Description=Fix CPU frequency scaling after suspend
After=suspend.target hibernate.target hybrid-sleep.target

[Service]
Type=oneshot
ExecStart=/home/your_username/cpu_frequency_fix.sh

[Install]
WantedBy=suspend.target hibernate.target hybrid-sleep.target

Enable the service:

sudo systemctl enable cpu_frequency_fix.service
sudo systemctl start cpu_frequency_fix.service

Step 3: Kernel Parameter Modifications

To permanently disable ACPI-based throttling, update your GRUB configuration:

sudo nano /etc/default/grub

Add the following parameters:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash amd_pstate=disable processor.ignore_ppc=1 acpi_cpufreq.enable_pcc=false intel_pstate=disable"

Update GRUB:

sudo update-grub

Testing and Monitoring

You can monitor the CPU frequencies using:

watch -n1 "grep 'cpu MHz' /proc/cpuinfo"

To stress-test and verify performance:

stress-ng --cpu $(nproc) --timeout 10s

Conclusion

After applying these steps, your AMD Ryzen CPU should scale correctly even after suspend, unlocking its full performance potential. This solution not only optimizes your Ubuntu experience but also ensures that your processor’s capabilities are fully utilized.

This method has been tested successfully on Ubuntu 25.04 with ASUS TUF Gaming A17 but should work with other AMD-powered systems as well.