Arch Linux

minorutkd

Member

Registered: 2019-03-21

Posts: 2

building v4l2loopback error

After recent system upgrade, building v4l2loopback failed.

dkms install --no-depmod v4l2loopback/0.15.0 -k 6.16.2-arch1-1
Sign command: /usr/lib/modules/6.16.2-arch1-1/build/scripts/sign-file
Signing key: /var/lib/dkms/mok.key
Public certificate (MOK): /var/lib/dkms/mok.pub

Building module(s)...(bad exit status: 2)
Failed command:
make -j4 KERNELRELEASE=6.16.2-arch1-1 KERNEL_DIR=/usr/lib/modules/6.16.2-arch1-1/build v4l2loopback

Error! Bad return status for module build on kernel: 6.16.2-arch1-1 (x86_64)
Consult /var/lib/dkms/v4l2loopback/0.15.0/build/make.log for more information.

cat /var/lib/dkms/v4l2loopback/0.15.0/build/make.log
DKMS (dkms-3.2.1) make.log for v4l2loopback/0.15.0 for kernel 6.16.2-arch1-1 (x86_64)
Sun Aug 24 16:58:34 JST 2025

Building module(s)
# command: make -j4 KERNELRELEASE=6.16.2-arch1-1 KERNEL_DIR=/usr/lib/modules/6.16.2-arch1-1/build v4l2loopback
grep: /etc/dkms/framework.conf.d/*.conf: No such file or directory

++++++ To sign the  module, you must set KBUILD_SIGN_KEY/KBUILD_SIGN_CERT to point to the signing key/certificate!
++++++ For your convenience, we try to read these variables as 'mok_signing_key' resp. 'mok_certificate' from /etc/dkms/framework.conf /etc/dkms/framework.conf.d/*.conf

++++++ If your certificate requires a password, pass it via the KBUILD_SIGN_PIN env-var!
grep: /etc/dkms/framework.conf.d/*.conf: No such file or directory
++++++ E.g. using 'export KBUILD_SIGN_PIN; read -s -p "Passphrase for signing key : " KBUILD_SIGN_PIN; sudo --preserve-env=KBUILD_SIGN_PIN make sign'

Building v4l2-loopback driver...
make -C /usr/lib/modules/6.16.2-arch1-1/build M=/var/lib/dkms/v4l2loopback/0.15.0/build KCPPFLAGS="" modules
make[1]: Entering directory '/usr/lib/modules/6.16.2-arch1-1/build'
make[2]: Entering directory '/var/lib/dkms/v4l2loopback/0.15.0/build'
  CC [M]  v4l2loopback.o
v4l2loopback.c: In function 'v4l2_loopback_add':
v4l2loopback.c:2904:9: error: implicit declaration of function 'setup_timer' [-Wimplicit-function-declaration]
2904 |         setup_timer(&dev->sustain_timer, sustain_timer_clb, nr);
      |         ^~~~~~~~~~~
make[4]: *** [/usr/lib/modules/6.16.2-arch1-1/build/scripts/Makefile.build:287: v4l2loopback.o] Error 1
make[3]: *** [/usr/lib/modules/6.16.2-arch1-1/build/Makefile:2003: .] Error 2
make[2]: *** [/usr/lib/modules/6.16.2-arch1-1/build/Makefile:248: __sub-make] Error 2
make[2]: Leaving directory '/var/lib/dkms/v4l2loopback/0.15.0/build'
make[1]: *** [Makefile:248: __sub-make] Error 2
make[1]: Leaving directory '/usr/lib/modules/6.16.2-arch1-1/build'
make: *** [Makefile:54: v4l2loopback.ko] Error 2

# exit code: 2
# elapsed time: 00:00:01

Xwang

Member

From: EU

Registered: 2012-05-14

Posts: 403

Re: building v4l2loopback error

I've the same identical issue with 6.16.3

loqs

Member

Registered: 2014-03-06

Posts: 18,631

Re: building v4l2loopback error

See https://gitlab.archlinux.org/archlinux/ … -/issues/4.

Last edited by loqs (2025-08-24 14:24:18)