Kernel building

There are two main methods for building the kernel. You can build locally on a Raspberry Pi, which will take a long time; or you can cross-compile, which is much quicker, but requires more setup.

Local building

On a Raspberry Pi, first install the latest version of Raspbian. Then boot your Pi, plug in Ethernet to give you access to the sources, and log in.

First install Git and the build dependencies:

sudo apt install git bc bison flex libssl-dev make

Next get the sources, which will take some time:

git clone --depth=1

Choosing sources

The git clone command above will download the current active branch (the one we are building Raspbian images from) without any history. Omitting the --depth=1 will download the entire repository, including the full history of all branches, but this takes much longer and occupies much more storage.

To download a different branch (again with no history), use the --branch option:

git clone --depth=1 --branch <branch>

where <branch> is the name of the branch that you wish to downlaod.

Refer to the original GitHub repository for information about the available branches.

Kernel configuration

Configure the kernel; as well as the default configuration, you may wish to configure your kernel in more detail or apply patches from another source, to add or remove required functionality:

Run the following commands, depending on your Raspberry Pi version.

Raspberry Pi 1, Pi Zero, Pi Zero W, and Compute Module default build configuration

cd linux
make bcmrpi_defconfig

Raspberry Pi 2, Pi 3, Pi 3+, and Compute Module 3 default build configuration

cd linux
make bcm2709_defconfig

Raspberry Pi 4

cd linux
make bcm2711_defconfig


Build and install the kernel, modules, and Device Tree blobs; this step can take a long time depending on the Pi model in use:

make -j4 zImage modules dtbs
sudo make modules_install
sudo cp arch/arm/boot/dts/*.dtb /boot/
sudo cp arch/arm/boot/dts/overlays/*.dtb* /boot/overlays/
sudo cp arch/arm/boot/dts/overlays/README /boot/overlays/
sudo cp arch/arm/boot/zImage /boot/$KERNEL.img

Note: On a Raspberry Pi 2/3/4, the -j4 flag splits the work between all four cores, speeding up compilation significantly.


First, you will need a suitable Linux cross-compilation host. We tend to use Ubuntu; since Raspbian is also a Debian distribution, it means many aspects are similar, such as the command lines.

You can either do this using VirtualBox (or VMWare) on Windows, or install it directly onto your computer. For reference, you can follow instructions online at Wikihow.

Install toolchain

Use the following command to download the toolchain to the home folder:

git clone ~/tools

Updating the $PATH environment variable makes the system aware of file locations needed for cross-compilation. On a 32-bit host system you can update and reload it using:

echo PATH=\$PATH:~/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin >> ~/.bashrc
source ~/.bashrc

If you are on a 64-bit host system, you should use:

echo PATH=\$PATH:~/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian-x64/bin >> ~/.bashrc
source ~/.bashrc

Get sources

To download the minimal source tree for the current branch, run:

git clone --depth=1

See Choosing sources above for instructions on how to choose a different branch.

Build sources

To build the sources for cross-compilation, make sure you have the dependencies needed on your machine by executing:

sudo apt install git bc bison flex libssl-dev make

If you find you need other things, please submit a pull request to change the documentation.

Enter the following commands to build the sources and Device Tree files:

For Pi 1, Pi Zero, Pi Zero W, or Compute Module:

cd linux
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- bcmrpi_defconfig

For Pi 2, Pi 3, Pi 3+, or Compute Module 3:

cd linux
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- bcm2709_defconfig

For Raspberry Pi 4:

cd linux
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- bcm2711_defconfig

Then, for all:

make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- zImage modules dtbs

Note: To speed up compilation on multiprocessor systems, and get some improvement on single processor ones, use -j n, where n is the number of processors * 1.5. Alternatively, feel free to experiment and see what works!

Install directly onto the SD card

Having built the kernel, you need to copy it onto your Raspberry Pi and install the modules; this is best done directly using an SD card reader.

First, use lsblk before and after plugging in your SD card to identify it. You should end up with something like this:


with sdb1 being the FAT (boot) partition, and sdb2 being the ext4 filesystem (root) partition.

If it's a NOOBS card, you should see something like this:


with sdb6 being the FAT (boot) partition, and sdb7 being the ext4 filesystem (root) partition.

Mount these first, adjusting the partition numbers for NOOBS cards (as necessary):

mkdir mnt
mkdir mnt/fat32
mkdir mnt/ext4
sudo mount /dev/sdb6 mnt/fat32
sudo mount /dev/sdb7 mnt/ext4

Next, install the modules:

sudo env PATH=$PATH make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- INSTALL_MOD_PATH=mnt/ext4 modules_install

Finally, copy the kernel and Device Tree blobs onto the SD card, making sure to back up your old kernel:

sudo cp mnt/fat32/$KERNEL.img mnt/fat32/$KERNEL-backup.img
sudo cp arch/arm/boot/zImage mnt/fat32/$KERNEL.img
sudo cp arch/arm/boot/dts/*.dtb mnt/fat32/
sudo cp arch/arm/boot/dts/overlays/*.dtb* mnt/fat32/overlays/
sudo cp arch/arm/boot/dts/overlays/README mnt/fat32/overlays/
sudo umount mnt/fat32
sudo umount mnt/ext4

Another option is to copy the kernel into the same place, but with a different filename - for instance, kernel-myconfig.img - rather than overwriting the kernel.img file. You can then edit the config.txt file to select the kernel that the Pi will boot into:


This has the advantage of keeping your kernel separate from the kernel image managed by the system and any automatic update tools, and allowing you to easily revert to a stock kernel in the event that your kernel cannot boot.

Finally, plug the card into the Pi and boot it!