*** This bug is a duplicate of bug 2128729 ***
https://bugs.launchpad.net/bugs/2128729
This is the same bug as
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2128729. That the
grub menu being hidden isn't mentioned there is because that is normal
and expected. The reason the OP mentions this is because it makes it
_much_ harder to recover the system, because the user cannot _see_ at
boot that there are choices. What grub really ought to do is: _always_
show the grub menu after a failed boot, with an infinite timeout, so
that it becomes fairly obvious that the user has to pick something other
than the default.
** This bug has been marked a duplicate of bug 2128729
Kernel 5.15.0-160 boots without any video output (on AMD)
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https://bugs.launchpad.net/bugs/2128904
Title:
black screen when booting 5.15.0-160-generic on AMD Renoir
Status in linux package in Ubuntu:
Incomplete
Bug description:
Summary:
Kernel 5.15.0-160-generic causes black screen on boot - AMD Renoir graphics
(ThinkPad T14s Gen 1)
Description:
System Information
Hardware: Lenovo ThinkPad T14s Gen 1 (AMD)
GPU: AMD Renoir [1002:1636] (rev d3)
OS: Linux Mint 21.2 Victoria (based on Ubuntu 22.04 LTS)
Affected Kernel: 5.15.0-160-generic
Working Kernel: 5.15.0-157-generic
Date Issue Occurred: October 18, 2025
Problem Description
After the automatic kernel update to 5.15.0-160-generic (released October 16,
2025), the system became completely unusable with a black screen on boot. The
login screen never appears, and the system is inaccessible via normal boot
methods.
Symptoms
Black screen after GRUB menu selection (no video output)
System appears to hang during boot process
Only accessible via recovery mode with nomodeset parameter
Brightness controls (Fn+F5/F6) non-functional
AMD GPU driver (amdgpu) fails to initialize
Technical Details
Error Messages in dmesg:
[drm:amdgpu_init [amdgpu]] ERROR VGACON disables amdgpu kernel modesetting.
This error appears multiple times during boot, indicating that the VGA
console driver (VGACON) is taking control before amdgpu can initialize,
preventing proper graphics initialization.
GPU Detection:
06:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc.
[AMD/ATI] Renoir [1002:1636] (rev d3)
Boot Parameters (Failed Boot):
BOOT_IMAGE=/boot/vmlinuz-5.15.0-160-generic
root=UUID=f43b6f6c-720a-4568-947b-fa182efb4811 ro quiet splash
Loaded Modules (Recovery Mode):
When booted in recovery mode with nomodeset, amdgpu module is present but not
loaded. Only basic framebuffer drivers (drm, drm_kms_helper) are active.
Impact
Severity: Critical - System completely unusable
Time Lost: Approximately 9-10 hours of troubleshooting
User Impact: Unable to work, required advanced Linux knowledge to recover
Accessibility: Recovery required understanding of GRUB, kernel parameters,
and initramfs
This is particularly severe because:
No warning was provided before the kernel update
System automatically selected the broken kernel as default
GRUB menu was hidden by default (GRUB_TIMEOUT=0, GRUB_TIMEOUT_STYLE=hidden)
Standard GRUB access keys (ESC/Shift) did not work
Required hardware-specific boot menu access (F12) to recover
Root Cause Analysis
The kernel regression appears to be a driver initialization race condition
where VGACON (VGA console driver) claims the graphics hardware before amdgpu
can initialize with kernel mode setting (KMS). Once VGACON has control, it
refuses to relinquish it to amdgpu, resulting in no functional graphics output.
Workaround Applied
The following steps were required to restore system functionality:
Removed incorrect GRUB parameters
Previous troubleshooting attempts had added:
amdgpu.si_support=1 amdgpu.cik_support=1
These parameters are for older AMD GPUs (Southern Islands/Sea Islands
2011-2013) and are inappropriate for Renoir (2020). They were removed, leaving
only:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
Configured early amdgpu loading
Added amdgpu to initramfs to ensure it loads before VGACON:
echo "amdgpu" >> /etc/initramfs-tools/modules
Enabled explicit kernel modesetting
Created modprobe configuration:
echo "options amdgpu modeset=1" > /etc/modprobe.d/amdgpu-kms.conf
Rebuilt initramfs and updated GRUB
sudo update-initramfs -u -k all
sudo update-grub
Set working kernel as default
Locked system to boot kernel 5.15.0-157-generic by name:
sudo grub-set-default
"gnulinux-5.15.0-157-generic-advanced-f43b6f6c-720a-4568-947b-fa182efb4811"
Made GRUB menu visible
Changed GRUB configuration to provide safety net:
GRUB_TIMEOUT=10
#GRUB_TIMEOUT_STYLE=hidden (commented out)
Verification
After applying workaround and booting kernel 5.15.0-157-generic:
System boots normally to login screen
amdgpu driver loads successfully (verified with lsmod | grep amdgpu)
No VGACON errors in dmesg
Brightness controls functional (Fn+F5/F6)
Boot parameters: ro quiet splash (no nomodeset required)
Graphics fully functional
Comparison: Working vs Broken Kernel
Kernel 5.15.0-157-generic (WORKS):
uname -r
5.15.0-157-generic
lsmod | grep amdgpu
amdgpu 9904128 20
drm 622592 11
gpu_sched,drm_kms_helper,amdgpu,drm_ttm_helper,ttm
dmesg | grep -i "amdgpu|vgacon" | grep -i error
(no errors)
Kernel 5.15.0-160-generic (BROKEN):
Black screen on boot
Cannot capture logs due to inaccessibility
Recovery mode shows repeated VGACON errors
amdgpu fails to initialize
Related Information
Similar Reports
Other users have reported similar issues with kernel 5.15.0-160-generic:
System freezes on AMD hardware
Boot failures requiring recovery mode
Black screen issues on various AMD GPU configurations
Affected Hardware
This likely affects:
Lenovo ThinkPad T14s Gen 1 (AMD) with Renoir graphics
Other systems with AMD Renoir APUs (4000-series mobile)
Potentially other AMD Ryzen + Vega configurations
Requests
Immediate (Urgent):
Fix kernel 5.15.0-161+ to resolve AMD Renoir initialization issues
Do NOT remove kernel 5.15.0-157 from repositories until fix is confirmed and
tested
Mark kernel 5.15.0-160 as problematic in update manager for affected hardware
Long-term (Important):
Implement kernel rollback mechanism - Allow users to easily revert to
previous kernel if system won't boot
Add kernel update warnings - Notify users before kernel changes default boot
option
Improve GRUB accessibility - Ensure GRUB menu is accessible (don't hide by
default, or ensure key intercept works)
Better pre-release testing - Test on common hardware configurations
(ThinkPads are extremely common)
Hardware-specific kernel holds - Allow users to "pin" kernels for specific
hardware
Additional Context
This bug represents a severe regression that makes systems completely
unusable. Users without advanced Linux knowledge would be unable to recover
their systems and might:
Reinstall the operating system (losing data and configuration)
Switch to another OS out of frustration
Require professional technical support
Be unable to access their computers for critical work
The lack of warning, combined with automatic kernel selection and hidden GRUB
menu, created a perfect storm that locked users out of their own systems.
Testing Offer
I am willing to test proposed fixes for kernel 5.15.0-161+ on my hardware and
provide detailed feedback.
Expected Behavior:
System should boot normally to login screen with full graphics functionality.
Actual Behavior:
Black screen, no video output, system completely inaccessible via normal boot.
Reproducibility:
100% reproducible - every boot attempt with kernel 5.15.0-160-generic results
in black screen.
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