Indeed, if I install raspberrypi-firmware-extra and I set 'start_x=1' and 'gpu_mem=128' in config.txt (no need for dtoverlay), then /dev/video0 is available and can be used. Tested with fswebcam: fswebcam -r 1280x1024 --no-banner image1.jpeg It does not work if I set values in extraconfig.txt, as pointed by Michal. I reported it upstream at https://github.com/raspberrypi/firmware/issues/1641 and asked if this function could be added.