v4l2loopback for Fedora Silverblue

---

A simple way to build v4l2loopback module on Fedora Silverblue flavours (Fedora kinoite).

This script will download automatically the last version of v4l2loopback from https://github.com/umlaeute/v4l2loopback.

Dependencies

1. Podman, check podman installation with the command:

    podman version
   

   The output is something like

    Client:       Podman Engine
    Version:      5.0.0-rc2
    API Version:  5.0.0-rc2
    Go Version:   go1.22.0
    Built:        Mon Feb 19 06:50:31 2024
    OS/Arch:      linux/amd64
   

Express build and installation

If you just want build and run, lets go!:

1. Edit Dockerfile to configure your Fedora Version, default is 40

   ARG FEDORA_VERSION=YOUR_VERSION

2. Build

    sh podman_build.sh --no-cache
   

3. Install the module as a systemd service

    sudo sh install.sh
   

4. Check if all is ok

    sudo dmesg
   

   Output will be:

    [18109.162005] videodev: Linux video capture interface: v2.00
    [18109.164951] v4l2loopback driver version 0.13.1 (snapshot) loaded
   

If module stop works just repeat all steps again.

Detailed Build

---

Preparing build to your Fedora Version

1. Checkout or download all this files on a directory, after download you must have this files:

    v4l2loopback-fedora-silverblue
    ├── Dockerfile
    ├── install.sh
    ├── load-v4l2loopback.sh
    ├── podman_build.sh
    ├── README.md
    └── uninstall.sh
   

2. Verify your Fedora version with the command

   uname -r

   The output is something like

    6.8.1-300.fc40.x86_64
   

   The fc40 says that we are using Fedora 40

   Edit file Dockerfile and change the first line to your version:

    ARG FEDORA_VERSION=40
   

Building

1. Open a terminal inside folder that you dowload an excecute the file podman_build.sh

   sh podman_build.sh
   

   A folder called build will be created and the module v4l2loopback.ko will be generated:

   ├── build
   │   └── v4l2loopback
   │       └── v4l2loopback.ko
   ├── Dockerfile
   ├── install.sh
   ├── load-v4l2loopback.sh
   ├── podman_build.sh
   ├── README.md
   └── uninstall.sh
   

2. Load module:

   sudo sh load-v4l2loopback.sh
   

3 Great! your module must be loaded and working.

4. Check with command:

   sudo dmesg
   

   Output will be:

   [18109.162005] videodev: Linux video capture interface: v2.00
   [18109.164951] v4l2loopback driver version 0.13.1 (snapshot) loaded
   

Possible or Inevitable Problems

1. You will have to repeat step 2 every time you restart your computer ( solution in the end of this document)

   sudo sh load-v4l2loopback.sh
   

2. Must repeat all building step if you update your kernel.

    sh podman_build.sh
    sudo sh load-v4l2loopback.sh
   

Load this module when system starts.

Certainly there are many ways to do that, but a simple way is creating a service, lets do that!

1. Execute the file install.sh

   sudo sh install.sh
   

   Output will be something like

   Creating a service on /etc/systemd/system/ ...
   Enable service...
   Starting service
   OK.Bye bye
   

2. Now the module will load before the user session starts, you can change install.sh script to adapt to your necessities.

3. To remove this service execute:

    sudo sh uninstall.sh
   

   output will be:

    Removing service...
    Removed "/etc/systemd/system/multi-user.target.wants/v4l2loopback-silverblue.service".
    Unloading module v4l2loopback
    Ok.Bye bye
   

Build diretory is empty.

Execute the following command

    sh podman_build.sh --no-cache

Can i use this in other distribution?

Sure you can! just adapt the dockerfile to your distribution.

https://github.com/moacirrf/v4l2loopback-fedora-silverblue/blob/main/Dockerfile

You can ask CHATGPT to convert dockerfile content to work with Ubuntu.

Next features

• Automatically rebuild the module if module refuse to load.
• Or a graphical notification when module refuse to load (hard to do).