[Bug 2136769] Re: v4l2loopback >= 0.14.0 breaks gstreamer/noble

** Tags added: jira-somerville-3749

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https://bugs.launchpad.net/bugs/2136769

Title:
v4l2loopback >= 0.14.0 breaks gstreamer/noble

Status in linux package in Ubuntu:
New
Status in linux-oem-6.17 package in Ubuntu:
Invalid
Status in v4l2loopback package in Ubuntu:
In Progress
Status in linux-oem-6.17 source package in Noble:
Triaged
Status in v4l2loopback source package in Noble:
Invalid
Status in linux-oem-6.17 source package in Plucky:
Invalid
Status in v4l2loopback source package in Plucky:
Invalid
Status in linux-oem-6.17 source package in Questing:
Invalid
Status in v4l2loopback source package in Questing:
In Progress
Status in linux-oem-6.17 source package in Resolute:
Invalid
Status in v4l2loopback source package in Resolute:
In Progress

Bug description:
Ubuntu complies v42loopback-dkms/questing into derived and generic
6.17 kernels. That is linux/questing, linux-oem-6.17/noble and linux-
hwe-6.17/noble, etc. have v4l2loopback.ko built from v4l2loopback-
dkms=0.15.0-0ubuntu2.

With v4l2loopback upstream commit 5092ea9
(https://github.com/v4l2loopback/v4l2loopback/commit/5092ea9a7667564fbfc7e4e4ae9d8a2b2757649f), or v4l2loopback >= v0.14.0, it breaks gstreamer/noble, but works fine with gstreamer/questing and gstreamer/resolute.

Therefore for linux-oem-6.17 kernels (linux-oem-6.14 is not affected),
v4l2-relayd dies again and again until disabled by systemd, and camera
access from browser will then fail.

==================================

ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: linux-image-6.14.0-1018-oem 6.14.0-1018.18
ProcVersionSignature: Ubuntu 6.14.0-1018.18-oem 6.14.11
Uname: Linux 6.14.0-1018-oem x86_64
NonfreeKernelModules: zfs
ApportVersion: 2.28.1-0ubuntu3.8
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: willedi 3549 F.... pipewire
                      willedi 3556 F.... wireplumber
 /dev/snd/seq: willedi 3549 F.... pipewire
CasperMD5CheckResult: pass
CurrentDesktop: MATE
Date: Wed Dec 17 20:44:14 2025
InstallationDate: Installed on 2025-12-15 (2 days ago)
InstallationMedia: Ubuntu-MATE 24.04.3 LTS "Noble Numbat" - Release amd64 (20250805.1)
IwConfig:
 lo no wireless extensions.

 enx4086cbb4dd85 no wireless extensions.

 wlp0s20f3 no wireless extensions.
MachineType: Dell Inc. Dell Pro 16 Plus PB16250
ProcFB: 0 xedrmfb
ProcKernelCmdLine: BOOT_IMAGE=/BOOT/ubuntu_z4e374@/vmlinuz-6.14.0-1018-oem root=ZFS=rpool/ROOT/ubuntu_z4e374 ro quiet splash vt.handoff=1
RelatedPackageVersions:
 linux-restricted-modules-6.14.0-1018-oem N/A
 linux-backports-modules-6.14.0-1018-oem N/A
 linux-firmware 20240318.git3b128b60-0ubuntu2.21
SourcePackage: linux-oem-6.14
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 08/26/2025
dmi.bios.release: 2.6
dmi.bios.vendor: Dell Inc.
dmi.bios.version: 2.6.1
dmi.board.name: 0PTFR0
dmi.board.vendor: Dell Inc.
dmi.board.version: A03
dmi.chassis.type: 10
dmi.chassis.vendor: Dell Inc.
dmi.ec.firmware.release: 1.9
dmi.modalias: dmi:bvnDellInc.:bvr2.6.1:bd08/26/2025:br2.6:efr1.9:svnDellInc.:pnDellPro16PlusPB16250:pvr:rvnDellInc.:rn0PTFR0:rvrA03:cvnDellInc.:ct10:cvr:sku0CDD:
dmi.product.family: Dell Pro Laptops
dmi.product.name: Dell Pro 16 Plus PB16250
dmi.product.sku: 0CDD
dmi.sys.vendor: Dell Inc.

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