developing v4l2loopback with a VM

Using Vagrant with the VirtualBox backend

SETUP

Use the Vagrantfile below for a Debian/testing based VM. Replace the host's /PATH/TO/v4l2loopback to the full path to the v4l2loopback sources on your disk.

• The VM needs to have all the goodies (VirtualBox extension pack) for sharing host folders and webcams (if you need that).

  apt install virtualbox-guest-dkms virtualbox-guest-dkms virtualbox-guest-utils
  

• Make the VM up-to-date apt update && apt dist-upgrade or similar

• Drop the unused stuff with apt autoremove; apt-get clean or similar

• Make sure that the vagrant user will end up in /vagrant/v4l2loopback when logging in. I did so by adding the following 2 lines at the very end of ~vagrant/.bashrc:

  cd /vagrant
  test -d v4l2loopback && cd v4l2loopback
  

• Power the VM off, and create an offline snapshot

• Boot the VM (with the share mounted onto /vagrant/v4l2loopback):

  vagrant up
  

• Create an online snapshot of the running VM

• Leave the VM running

scripts

You can find a vbox-restart script in the vagrant/ directory of this repository. Running it (give the UUID of a running VM) will:

• do a hard shutdown of the given VM
• restore the last snapshot of the given VM
• start the running VM
• (optionally) attach the host's webcam to VM

Workflow

• Open v4l2loopback.c in your favourite editor and hack away
• Whenever you feel like testing, do the following in a separate terminal:

me@host:~/v4l2loopback$ cd vagrant

me@host:~/v4l2loopback/vagrant$ ./vbox-restart -a
me@host:~/v4l2loopback/vagrant$ vagrant ssh
vagrant@/vagrant/v4l2loopback$ make clean
vagrant@/vagrant/v4l2loopback$ make modprobe
vagrant@/vagrant/v4l2loopback$ (do some tests)

if the machine freezes, or something else really bad happens to it, just re-run ./vbox-restart and start anew.

Resources

Vagrantfile

Vagrant.configure("2") do |config|
  config.vm.box = "debian/contrib-testing64"
  config.vm.synced_folder "/PATH/TO/v4l2loopback", "/vagrant/v4l2loopback"
end