Public bug reported:
Package: `linux` (Ubuntu 26.04.1)
## Background
Since the update to `7.0.0-38.38`, a horizontal band of broken pixels
flashes on screen for a single frame. The band shows content from an
older frame - text from another window, or a strip of the wallpaper. It
looks like the monitor receives a frame that was not finished yet.
It happens on the first frame of an animation, mostly when opening the
Activities overview. It is a lot more frequent under load, for example
right after login, when several apps open at once.
Booting `7.0.0-34.34` on the same install makes it go away completely.
Nothing else changes between the two boots.
The band is NOT captured by the GNOME screen recorder, it is only
visible on the monitor itself. The frame below was taken with a phone at
60 fps. There are no `amdgpu` or `drm` errors on `journalctl -k`.
Windows OS on the same machine does not show it.
## System
| Item | Value |
| --- | --- |
| GPU | Radeon RX 9070 XT (Navi 48) `[1002:7550]` rev c0, PowerColor Reaper |
| Driver | `amdgpu`, DCN 4.0.1, DMUB `0x0A000800` |
| Monitor | 3440x1440 at 240 Hz, DisplayPort (`DP-3`), VRR off |
| Good kernel | `7.0.0-34-generic` (7.0.0-34.34) |
| Bad kernel | `7.0.0-38-generic` (7.0.0-38.38) |
| Mesa | 26.0.8-1ubuntu0.3 |
| Desktop | GNOME Shell 50.1, mutter 50.1-0ubuntu2.4, Wayland |
| Firmware | linux-firmware 20260319.git217ca6e4.1ubuntu |
## Steps to Reproduce
1. Boot `7.0.0-38-generic` with an RX 9070 XT and a high refresh rate monitor
2. Log in to the GNOME Wayland session
3. Open a few windows (browser, terminal)
4. Press **Super** repeatedly to open and close the Activities overview
5. Notice that a horizontal band flashes for one frame as the animation starts
It takes me less than 30 presses. Right after login it shows up without
pressing anything.
## Expected Behavior
No band, same as `7.0.0-34-generic`.
## What I tried on 7.0.0-38
| Change | Result |
| --- | --- |
| Refresh rate 240 Hz → 120 Hz | No effect |
| `AMD_DEBUG=nodcc` | No effect |
| `MUTTER_DEBUG_FORCE_KMS_MODE=simple` and `MUTTER_DEBUG_USE_KMS_MODIFIERS=0` |
No effect |
| `amdgpu.dcdebugmask=0x20000` | No effect |
| `power_dpm_force_performance_level` set to `high` | Band becomes rare, still
there at login |
| Boot `7.0.0-34-generic`, level on `auto` | Gone |
Since `high` only makes it rare, my guess is that it depends on how long
the GPU takes to finish the frame. That is only a guess, I did not
bisect between 34 and 38.
## Frame example
Band over a terminal window:
I can attach the full phone videos and test any kernel build if need be.
ProblemType: Bug
DistroRelease: Ubuntu 26.04
Package: linux-image-7.0.0-38-generic 7.0.0-38.38
ProcVersionSignature: Ubuntu 7.0.0-38.38-generic 7.0.14
Uname: Linux 7.0.0-38-generic x86_64
ApportVersion: 2.34.1-0ubuntu0.1
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: ixavier 4262 F.... wireplumber
/dev/snd/controlC2: ixavier 4262 F.... wireplumber
/dev/snd/controlC1: ixavier 4262 F.... wireplumber
/dev/snd/seq: ixavier 4237 F.... pipewire
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Tue Oct 13 10:49:15 2026
InstallationDate: Installed on 2025-10-01 (377 days ago)
InstallationMedia: Ubuntu 24.04.3 LTS "Noble Numbat" - Release amd64
(20250805.1)
IwDevWlp0s20f3Link: Not connected.
MachineType: ASUS System Product Name
ProcFB: 0 amdgpudrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-7.0.0-38-generic
root=UUID=bd74485c-851e-4f76-b2af-1c84ee1d58cc ro quiet splash
crashkernel=2G-4G:320M,4G-32G:512M,32G-64G:1024M,64G-128G:2048M,128G-:4096M
SourcePackage: linux
UpgradeStatus: Upgraded to resolute on 2026-09-05 (38 days ago)
dmi.bios.date: 10/09/2025
dmi.bios.release: 18.25
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 1825
dmi.board.asset.tag: Default string
dmi.board.name: ROG STRIX B760-I 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.:bvr1825:bd10/09/2025:br18.25:svnASUS:pnSystemProductName:pvrSystemVersion:rvnASUSTeKCOMPUTERINC.:rnROGSTRIXB760-IGAMINGWIFI:rvrRev1.xx:cvnDefaultstring:ct3:cvrDefaultstring:skuSKU:pfaTobefilledbyO.E.M.:
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 (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug resolute wayland-session
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https://bugs.launchpad.net/bugs/2170707
Title:
[amdgpu] RX 9070 XT: one-frame bands of old screen content since
7.0.0-38 (7.0.0-34 is fine)
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