Qubes OS 4.3 pre-release: graphical corruptions in GTK4 apps in Fedora 41-based dom0

[aronowski]

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Qubes OS release

4.3.202409242200 (pre-release)

Brief summary

Graphical corruptions in some GTK4 apps due to mesa regressions in Fedora 41-based dom0.

Possibly related to #9389, but creating a separate ticket after a chat with @marmarek during the hackathon at Qubes Summit 2024, considering the Qubes OS release difference and the difference between AppVMs and dom0.

Steps to reproduce

Download Qubes 4.3 pre-release ISO from https://openqa.qubes-os.org/tests/113304/asset/iso/Qubes-4.3.202409242200-x86_64.iso.

Install the system as usual, making sure the fedora-40-xfce template gets installed.

Log in and install Loupe as an example GTK4 application.

user@dom0:~$ sudo qubes-dom0-update --action=install loupe -y

Launch Loupe - a "hall of mirrors" graphical error should show up whenever some screen update is being drawn at the place, where the application window should be drawn (usually the center of the screen).

Let's downgrade Mesa to the one shipped with Fedora 40's initial release (i.e. its own fedora repository, not the updates repository).

Install Fedora 40 GPG key:

user@dom0:~$ qvm-run --pass-io fedora-40-xfce 'cat /etc/pki/rpm-gpg/RPM-GPG-KEY-fedora-40-x86_64' > /home/user/RPM-GPG-KEY-fedora-40-x86_64
user@dom0:~$ sudo rpm --import RPM-GPG-KEY-fedora-40-x86_64
user@dom0:~$ sudo cp RPM-GPG-KEY-fedora-40-x86_64 /etc/pki/rpm-gpg/

Create a file referring to the aforementioned repository:

user@dom0:~$ cat /etc/yum.repos.d/fedora-40.repo 
[fedora-40]
name=Fedora 40 - $basearch
metalink=https://mirrors.fedoraproject.org/metalink?repo=fedora-40&arch=$basearch
enabled=1
metadata_expire=7d
repo_gpgcheck=0
type=rpm
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-fedora-40-$basearch
skip_if_unavailable=False

Downgrade Mesa:

user@dom0:~$ sudo qubes-dom0-update --disablerepo='*' --enablerepo='fedora-40' --action=downgrade mesa-dri-drivers -y
user@dom0:~$ rpm -qa 'mesa-*'
mesa-libxatracker-24.2.3-2.fc41.x86_64
mesa-filesystem-24.0.5-1.fc40.x86_64
mesa-libglapi-24.0.5-1.fc40.x86_64
mesa-dri-drivers-24.0.5-1.fc40.x86_64
mesa-libgbm-24.0.5-1.fc40.x86_64
mesa-libEGL-24.0.5-1.fc40.x86_64
mesa-libGL-24.0.5-1.fc40.x86_64
mesa-va-drivers-24.0.5-1.fc40.x86_64
mesa-vulkan-drivers-24.0.5-1.fc40.x86_64

Launch Loupe - the application window should be either drawn properly this very moment or after clicking on any window or the XFCE4 desktop.

The steps described above are a recreation of the initial research of mine, that took place during the hackathon at Qubes Summit 2024. Bisecting the upstream mesa codebase, building and installing RPMs from it should narrow down the search for the problematic code much better.

Expected behavior

Windows of apps like Loupe are rendered properly.

Actual behavior

Windows of apps like Loupe are not displayed, and graphical anomalies take their place.