Getting Small - Roll your own IoT Linux with Buildroot

Whether you need a tiny OS for 1MB of flash memory or a complex Linux with a graphical stack, you can quickly set up a working operating system using Buildroot.

- Arnout Vandercapelle

To put together a Linux-based IoT system, you need a quick and easy approach to getting a base system up and running. And while you are at it, you also need to keep an eye on the flash footprint – some IoT platforms only have 64MB flash memory. You will want to keep control of the software included in the system, and you’ll want to be able to add your own applications easily. Last but not least, you will need to pay attention to security and comply with both open source and proprietary licenses.

The Buildroot build system [1] will help you with these tasks. Buildroot, which emerged in the early 2000s from the µClinux and Busybox projects, focuses on creating systems with a minimal footprint. Buildroot is easier to use and conceptually simpler than Yocto (see the article on Yocto starting on p. 16 of this issue). If you don’t need Yocto’s expansive capabilities, with its modular layer system and other advanced features, and you just want to generate an OS for an embedded device, Buildroot is often the better choice.

Buildroot can generate:

• a cross-compilation toolchain

• a root file system

• a Linux kernel image

• a bootloader for the target device

A selection tool based on the menu system of the Linux kernel lets you specify the required packages and the associated configuration options. This menu-driven approach helps ensure you have the components you need and makes it easy to leave out any components you don’t need to minimize the flash footprint.