This note includes a set of steps to build the Linux kernel locally for Raspberry Pi SBC (i.e., building the kernel on the board.)

Preparation

  1. Update the system

     sudo apt update
 sudo apt upgrade
 sudo rpi-update
 sudo reboot

  2. Install necessary tools

     sudo apt install git bc bison flex libssl-dev build-essential

  3. Create a workspace and download the kernel code

     mkdir ~/workspace; cd ~/workspace
 git clone --depth=1 https://github.com/raspberrypi/linux

    The git command will create a linux directory, download and put the code inside the directory.

Kernel configuration

First, prepare the default configuration by running the following commands, depending on the Raspberry Pi version:

cd ~/workspace/linux
# For Raspberry Pi 1, Pi Zero, Pi Zero W, and Compute Module
make bcmrpi_defconfig
# For Raspberry Pi 2, Pi 3, Pi 3+, and Compute Module 3
make bcm2709_defconfig
# For Raspberry Pi 4
make bcm2711_defconfig

Next, we need to adjust the LOCALVERSION to ensure the new kernel does not have the same version string as the upstream. This helps to clarify that we are running our kernel by invoking uname command and ensures existing modules in /lib/modules are not overwritten. To do so, change the following line in .config

CONFIG_LOCALVERSION="-v7l-<your own string>"

Building and installation

Build and install the kernel, modules, and device tree blobs:

make -j4 zImage modules dtbs
sudo make modules_install

This step can take a long time (depending on the Pi model in use). Next, we install the newly-created module into /lib/modules:

sudo make modules_install

Then copy the kernel and device tree blobs files to the /boot partition:

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 that we can copy the kernel file (i.e., kernel.img file) into the same place, but with a different filename - for instance, my_new_kernel.img. We then edit the config.txt file to select the kernel that the Pi will boot into:

kernel= my_new_kernel.img

Finally, reboot the Pi

sudo reboot