So, you’re building the next big smart microwave with an integrated tablet. That’s great! Except now you need to build a custom operating system to help manage everything without burning your food (and hopefully your house down). You need a project that can help you create an effective Linux build, and it has to be fast. We’ve got good news! There are some great projects to help you do it. The real question is, which one should you go with?
There are quite a few options to choose from, but for this article, we’ll focus on the two most popular frameworks out there: Yocto and Buildroot. These two projects have become go-to’s for teams looking to build embedded systems for quite different reasons, and they offer unique benefits (and some drawbacks) that make them worth a look. So, let’s break them down to see which is the better choice for you.
Before we start, some clarification
It’s worth noting that Yocto and Buildroot are NOT Linux distros themselves, but projects that help developers build embedded systems based on Linux (in the case of Yocto, the output is a Linux distribution, while Buildroot outputs a root file system that can be used to build a distribution).
This is an important distinction, because it gets into the differences between the two projects, and why they’re each so popular. With that out of the way, back to our regularly scheduled programming.
Introducing the contenders
Let’s start by breaking down each of our two big contenders to see what they bring to the table.
Yocto is an umbrella project that focuses on open-embedded core which outputs Linux distributions for embedded systems regardless of hardware architecture. The key to remember is that Yocto itself isn’t actually a distribution but rather a framework that lets you build them. Yocto has become a go-to tool because it lets developers and embedded systems makers create Linux versions that are tailored to their hardware and software limitations and are application-specific.
More importantly, Yocto is known for its flexibility thanks to its multiple existing tools as well as its extensive open-source support. This includes countless tools, maintenance, templates, and community offerings that allow for incredibly specific builds. Yocto maintains three key components:
- BitBake – this is essentially Yocto’s build system engine, and it creates recipes – task lists needed to build specific systems – as well as parsing metadata and carrying out recipes.
- OpenEmbedded-Core – the metadata that holds the basic recipes, related files, and classes needed to create systems. These are built to be generic so as to be common to a variety of OpenEmbedded-based systems
- Poky – a full-platform build Linux-based tool and a variety of other technologies which lets teams reliably and quickly develop new systems. Poky generates filesystem images based on a variety of architectures. The standard example is a QEMU full-system emulation, making it a good test platform for embedded software.
Yocto has also become incredibly popular because it allows other key components (such as QT, Chromium, LLVM, and more) to be built into your embedded distribution.
Buildroot is a set of makefiles and scripts that make creating an embedded Linux distribution from source code easier. Unlike Yocto, which is a full project that includes multiple layers and tools, Buildroot is built around simplicity. The core Buildroot tool is kept as minimalistic as possible to avoid complexity and extended build times. This makes it easier to understand and use. For instance, Buildroot builds will reuse readily available tools like kconfig where possible instead of creating new ones for each custom distribution.
As such, Buildroot is “purpose-agnostic” and is widely usable across systems. Another interesting outcome of this philosophy is that Buildroot generates a root filesystem image as opposed to a full-on distribution. This means that you need to regenerate an entire image whenever an update is necessary. This is by design, as the project team follows the philosophy that embedded systems are different from desktop or server distributions by default. A failure or partial update could be catastrophic, so rebuilding the image from scratch avoids the issue entirely.
So, which one is better?
Not to sound like a cop-out, but it’s complicated. Which is better largely depends on what you’re looking for and what you’re planning on making. So, let’s break it down to see which one you should choose:
Why you should use Yocto
There are some clear advantages to using Yocto, despite its greater complexity. Perhaps the biggest is the fact that Yocto is a widely used – and widely supported – project featuring a highly active dev community creating new tools, layers, and features for it. Additionally, it’s driven by the Linux Foundation, which adds to its bonafides.
Another big benefit of Yocto is its implementation of layers, which can be used for anything from adding functionality to targeting platforms that aren’t available in project releases. Additionally, they can add unique features such as custom browser that offer even further tailoring capabilities to Yocto itself.
Yocto also has the widest device support of any similar project due to its support from several semiconductor and board producers. This, in addition to the vibrant Yocto ecosystem, means that there’s a massive variety of SDKs, tools, and features available to add to a custom Yocto build.
All of this adds up to make Yocto a highly customizable, strongly supported tool for devs looking to build an embedded system.
Disadvantages for Yocto
Even so, there are some drawbacks to Yocto. For one, there’s a slightly steep learning curve when getting started with the project. It may simply not make sense to get started for smaller, individual projects or small teams with time constraints. Additionally, Yocto is known to have build times that are quite long. This reduces iteration frequency, and for projects on a tight deadline, might make it less than ideal.
Why you should use Buildroot
Buildroot is built to be easy – from the way it runs to its outputs, it’s made to be simple and fast. Its core build system is written in Make and is short enough that devs can understand the whole thing without having to sacrifice learning time. As we mentioned above, this also means that Buildroot uses standard Makefiles and kconfig for configuration, two widely used and supported tools made by the Linux kernel community.
Buildroot is also a darling of the open-source community, as it features less “corporate” involvement. This means that there is more customizability and ability to make the system as unique as necessary to fit a dev team’s needs.
Finally, one of the most helpful features Buildroot offers is that it disables optional build-time settings, opting instead to create the smallest possible images out of the box. This significantly reduces build times and compute resources necessary (at the expense of a more flexible build). For smaller teams, or those with resource constraints, it could be an ideal solution.
We would be remiss if we didn’t start with the obvious – a lack of corporate support. Although for a lot of devs that might be a benefit, it comes with some significant downsides. Namely, a smaller community and less active ecosystem. Additionally, it also means less widespread support. So, if you have an issue, you’ll likely have to deal with it yourself, or learn how to do it, since many devs would rather focus on more broadly used tools.
Another big drawback to Buildroot is its lack of incremental builds. Whenever you need to make an update, even a small one, you need to remake the image from scratch, adding unnecessary time to your dev cycle.
Additionally, Buildroot’s biggest draw – its focus on simplicity – means that customizing it and creating a truly unique system is much harder than with Yocto.
You still haven’t answered the question
We know, we know. But the truth is, there’s no right or wrong answer here, just a better or worse use case. Yocto is a much better tool when working on a larger project with more resources and offers more time. It’s simply more customizable, more widely supported, and more compatible with a wider number of embedded device boards and semiconductors.
On the other hand, Buildroot is great if you’re working on a small project and are simply looking for a fast, frills-free solution to build an embedded system.
The real answer is that before you get started, you should understand the scope of the project, the resources (time, compute, hardware, team size, support) available, and make a decision that gives your team the best chance to succeed.