Public bug reported: Dear Ubuntu maintainers, On Ubuntu 22.04 with the HWE 6.8 kernel, the current `v4l2loopback-dkms` package (version 0.12.7-2ubuntu2~22.04.1) fails to build due to a removed kernel API (`strlcpy`).
The upstream `v4l2loopback` project has already addressed this issue in version 0.15.0 by switching to `strscpy`. Could you please consider updating the package to version 0.15.0, or backporting the relevant fix? # Bug analyze: kernel 6.8.0 remove the function "strlcpy", but the v4l2loopback-dkms 0.12.7 still use it. # kernel version: ``` $ uname -a Linux c 6.8.0-60-generic #63~22.04.1-Ubuntu SMP PREEMPT_DYNAMIC Tue Apr 22 19:00:15 UTC 2 x86_64 x86_64 x86_64 GNU/Linux ``` # apt Default version: 0.12.7 ``` $ apt-cache policy v4l2loopback-dkms v4l2loopback-dkms: Installed: (none) Candidate: 0.12.7-2ubuntu2~22.04.1 Version table: 0.12.7-2ubuntu2~22.04.1 500 ``` # install error message ``` $ sudo apt install -f Reading package lists... Done Building dependency tree... Done Reading state information... Done 0 upgraded, 0 newly installed, 0 to remove and 95 not upgraded. 1 not fully installed or removed. After this operation, 0 B of additional disk space will be used. Setting up v4l2loopback-dkms (0.12.7-2ubuntu2~22.04.1) ... Removing old v4l2loopback-0.12.7 DKMS files... Deleting module v4l2loopback-0.12.7 completely from the DKMS tree. Loading new v4l2loopback-0.12.7 DKMS files... Building for 6.8.0-60-generic Building initial module for 6.8.0-60-generic ERROR: Cannot create report: [Errno 17] File exists: '/var/crash/v4l2loopback-dk ms.0.crash' Error! Bad return status for module build on kernel: 6.8.0-60-generic (x86_64) Consult /var/lib/dkms/v4l2loopback/0.12.7/build/make.log for more information. dpkg: error processing package v4l2loopback-dkms (--configure): installed v4l2loopback-dkms package post-installation script subprocess returne d error exit status 10 Errors were encountered while processing: v4l2loopback-dkms E: Sub-process /usr/bin/dpkg returned an error code (1) ``` logs ``` $ cat /var/lib/dkms/v4l2loopback/0.12.7/build/make.log DKMS make.log for v4l2loopback-0.12.7 for kernel 6.8.0-60-generic (x86_64) 2025年07月09日 星期三 10:39:23 CST Building v4l2-loopback driver... make -C /lib/modules/6.8.0-60-generic/build M=/var/lib/dkms/v4l2loopback/0.12.7/build modules CC=x86_64-linux-gnu-gcc-12 make[1]: Entering directory '/usr/src/linux-headers-6.8.0-60-generic' CC [M] /var/lib/dkms/v4l2loopback/0.12.7/build/v4l2loopback.o /var/lib/dkms/v4l2loopback/0.12.7/build/v4l2loopback.c: In function ‘vidioc_querycap’: /var/lib/dkms/v4l2loopback/0.12.7/build/v4l2loopback.c:727:9: error: implicit declaration of function ‘strlcpy’; did you mean ‘strscpy’? [-Werror=implicit-function-declaration] 727 | strlcpy(cap->driver, "v4l2 loopback", sizeof(cap->driver)); | ^~~~~~~ | strscpy cc1: some warnings being treated as errors make[3]: *** [scripts/Makefile.build:243: /var/lib/dkms/v4l2loopback/0.12.7/build/v4l2loopback.o] Error 1 make[2]: *** [/usr/src/linux-headers-6.8.0-60-generic/Makefile:1925: /var/lib/dkms/v4l2loopback/0.12.7/build] Error 2 make[1]: *** [Makefile:240: __sub-make] Error 2 make[1]: Leaving directory '/usr/src/linux-headers-6.8.0-60-generic' make: *** [Makefile:43: v4l2loopback.ko] Error 2 ``` # workaround: Manually installing the upstream version 0.15.0 works correctly with kernel 6.8. This version contains the compatibility fix: ``` #if LINUX_VERSION_CODE < KERNEL_VERSION(4, 3, 0) #define strscpy strlcpy #endif ``` ``` sudo apt purge v4l2loopback-dkms sudo apt install git dkms build-essential linux-headers-$(uname -r) git clone https://github.com/umlaeute/v4l2loopback.git sudo mkdir -p /usr/src/v4l2loopback-0.15.0 sudo cp -r * /usr/src/v4l2loopback-0.15.0/ cd /usr/src/v4l2loopback-0.15.0/ sudo dkms add -m v4l2loopback -v 0.15.0 sudo dkms build -m v4l2loopback -v 0.15.0 sudo dkms install -m v4l2loopback -v 0.15.0 //avoid apt install v4l2loopback-dkms again sudo apt-mark hold v4l2loopback-dkms apt-mark showhold ``` # Impact This issue affects all Ubuntu 22.04 LTS users who have received the 6.8 HWE kernel and attempt to install v4l2loopback-dkms. Until the package is updated, it cannot be installed using the default Ubuntu repositories. Thank you for maintaining Ubuntu! ** Affects: v4l2loopback (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2116230 Title: ubuntu22 can't install v4l2loopback-dkms 0.12.7 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/v4l2loopback/+bug/2116230/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
