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An out of the box Raspberry Pi Raspbian distro with a realtime kernel. The kernel is a RaspberryPi kernel patched with the Preempt RT patch. Kernel patches are taken from here.

RealtimePi uses CustomPiOS, and you can use RealtimePi as a base image for CustomPiOS to make your own realtime kernel-based disros.


RealtimePi is 100% free and open source and maintained by Guy Sheffer. If its helping your life, your organisation or makes you happy, please consider making a donation. It means I can code more and worry less about my balance. Any amount counts. Also many thanks to people contributing code.


Where to get it?

Official mirror is here

Nightly builds are available here (currently built on demand)

How to use it?

  1. Unzip the image and install it to an SD card like any other Raspberry Pi image
  2. Configure your WiFi by editing realtimepi-wpa-supplicant.txt at the root of the flashed card when using it like a flash drive
  3. Boot the Pi from the SD card
  4. Hostname is realtimepi (not raspberrypi as usual)


  • Raspberrypi, any.
  • 2A power supply


  • Realtime kernel out of the box for both armv6 and armv7. All Pies that Raspbian supports are supported.
  • Tools to configure the network via text files /boot



  1. qemu-arm-static
  2. CustomPiOS
  3. Downloaded Raspbian image.
  4. root privileges for chroot
  5. Bash
  6. realpath
  7. sudo (the script itself calls it, running as root without sudo won't work)

Build RealtimePi From within Raspbian / Debian / Ubuntu

RealtimePi can be built from Debian, Ubuntu, Raspbian. Build requires about 3.5 GB of free space available. Note it takes about 6 hours to builds the kernel, and 12 for both kernels! You can build it by issuing the following commands:

sudo apt-get install realpath p7zip-full qemu-user-static

git clone
git clone
cd RealtimePi/src/image
wget -c --trust-server-names ''
cd ..
sudo modprobe loop
sudo bash -x ./build_dist

Building RealtimePi Variants

RealtimePi supports building variants, which are builds with changes from the main release build. An example and other variants are available in the folder src/variants/example.

To build a variant use:

sudo bash -x ./build_dist [Variant]

Building Using Vagrant

There is a vagrant machine configuration to let build RealtimePi in case your build environment behaves differently. Unless you do extra configuration, vagrant must run as root to have nfs folder sync working.

To use it:

sudo apt-get install vagrant nfs-kernel-server
sudo vagrant plugin install vagrant-nfs_guest
sudo modprobe nfs
cd RealtimePi/src/vagrant
sudo vagrant up

After provisioning the machine, its also possible to run a nightly build which updates from devel using:

cd RealtimePi/src/vagrant

To build a variant on the machine simply run:

cd RealtimePi/src/vagrant [Variant]


  1. If needed, override existing config settings by creating a new file src/config.local. You can override all settings found in src/config. If you need to override the path to the Raspbian image to use for building RealtimePi, override the path to be used in ZIP_IMG. By default, the most recent file matching * found in src/image will be used.
  2. Run src/build_dist as root.
  3. The final image will be created in src/workspace

Code contribution would be appreciated!

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