While updating my Archlinux packages with _ packman -Syu, I see that dkms fails to install modules:

(11/23) Install DKMS modules
==> dkms install --no-depmod v4l2loopback-dc/2.1.2 -k 6.8.5-arch1-1
Error! Bad return status for module build on kernel: 6.8.5-arch1-1 (x86_64)
Consult /var/lib/dkms/v4l2loopback-dc/2.1.2/build/make.log for more information.
==> WARNING: `dkms install --no-depmod v4l2loopback-dc/2.1.2 -k 6.8.5-arch1-1' exited 10
==> dkms install --no-depmod v4l2loopback/0.13.1 -k 6.8.5-arch1-1
==> depmod 6.8.5-arch1-1
(12/23) Updating TeXLive filename database...

In the log file (translated):

DKMS make.log for v4l2loopback-dc-2.1.2 for kernel 6.8.5-arch1-1 (x86_64)
Tue 16 Apr 2024 07:56:42 +03
make -C /lib/modules/6.8.5-arch1-1/build M=/var/lib/dkms/v4l2loopback-dc/2.1.2/build modules
make[1]: enter directory "/usr/lib/modules/6.8.5-arch1-1/build"
   CC [M] /var/lib/dkms/v4l2loopback-dc/2.1.2/build/v4l2loopback-dc.o
/var/lib/dkms/v4l2loopback-dc/2.1.2/build/v4l2loopback-dc.c: In the "vidioc_querycap" function:
/var/lib/dkms/v4l2loopback-dc/2.1.2/build/v4l2loopback-dc.c:622:3: error: implicit function declaration 'strlcpy'; did you mean "strscpy"? [-Werror=implicit-function-declaration]
   622 | strlcpy(cap->driver, "Droidcam", sizeof(cap->driver));
       | ^~~~~~~
       | strscpy
cc1: some warnings are considered errors
make[3]: *** [scripts/Makefile.build:243: /var/lib/dkms/v4l2loopback-dc/2.1.2/build/v4l2loopback-dc.o] Error 1
make[2]: *** [/usr/lib/modules/6.8.5-arch1-1/build/Makefile:1921: /var/lib/dkms/v4l2loopback-dc/2.1.2/build] Error 2
make[1]: *** [Makefile:240: __sub-make] Error 2
make[1]: exit from the directory "/usr/lib/modules/6.8.5-arch1-1/build"
make: *** [Makefile:8: all] Error 2

Is it a bug inside v4l2loopback source code or is it wrong dependencies? Thanks

1 Answer 1


This is caused by the final removal of strlcpy() (deemed unsafe) in Linux 6.8.x after all its in-kernel users switched to strscpy(). Usually "external" users (out-of-tree kernel modules) can lag a bit for such changes.

Droidcam's v4l2loopback-dc did fix this in version 2.1.3 with this commit on 2024-03-26:

Version 2.1.3

Use strscpy instead of strlcpy.
Linux 6.8 has removed strlcpy.

So you'll have to wait Archlinux picks version 2.1.3 or apply the patch yourself.

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