Build a Simple Linux Kernel Using Buildroot

Introduction

Welcome to this guide on how to build a Linux kernel using Buildroot!

This guide will give you a basic introduction to Linux kernel development. By the end of this guide you will know how to set up a Buildroot project, config the project, and flash the image to an SD card and have it running on a Raspberry Pi.

Prerequisites

Before you embark on your Buildroot adventure, make sure your PC isn't begging for more space because of all the memes and apps you don't use.

Aim for at least ~35GB of free space.

Ensure that you have the necessary packages on your Linux machine found in the requirements section within Buildroot Doc

Some minimal familiarity with Embedded Systems and Linux Ubuntu OS, as this will be the main OS we will be using.

Before we start, we need to understand what Buildroot is, and I'll make sure for it to be short and sweet!

What is Buildroot?

To use their own definition, "Buildroot is a simple, efficient and easy-to-use tool to generate embedded Linux systems through cross-compilation.". Cross-compilation is basically building software (SW) on one platform to be used on another platform.

Now, let’s get this started!

Building a Linux Kernel

Clone the GitHub repo to download Buildroot using the following command.

$ git clone https://gitlab.com/buildroot.org/buildroot.git

Once downloaded, open the newly created buildroot directory.

$ cd buildroot

Grab the configuration file.

$ make rasberrypi4_defconfig

• This will create a config.in file into your local buildroot directory.

Time to config the kernel configuration. Run make menuconfig to access Buildroot's configuration menu. Here, specify the target architecture, select desired packages and features, and configure any custom settings according to your project requirements.

For my case, I will just be updating the startup boot manager. This is found in System Configuration -> System banner

$ make menuconfig

Navigate to System Configuration and update System banner

Exit and save your kernel config

Build your kernel

$ make

After two hours later...

You should have your bootable image inside the output/images directory that you can add to your SD card

Insert the SD card into the Raspberry Pi 4 and power it on to boot into the custom Linux system.

Conclusion

By following these steps and along with installing the prerequisites, you will have everything you need to build a simple Linux kernel using Buildroot.

I can’t wait to see what you’ll build; if you follow these steps and get stuck or have any questions, feel free to reach out on LinkedIn or send a DM on Twitter.

Cover Photo by Stefan Cosma on Unsplash