FAQ: Buildroot vs. Yocto Project vs. Bob the Builder

Building Code Modules for Embedded Linux: A Comparison of Build Systems

This comparison focuses exclusively on the best methods for developers to build a single code module (e.g., a library or application) for an embedded Linux system. We are not concerned with building complete system images. Instead, we'll examine how each tool helps a developer compile, link, and prepare code for an embedded target.

Key Principle: The module's build system should be triggered independently and not rely on the framework itself to initiate the build. This ensures the module remains portable and can be built on different systems without depending on the specific framework.

Buildroot

• Relevance for module development: Buildroot can be adapted to build individual modules, leveraging its cross-compilation toolchain and dependency management. However, it may require extra effort to separate module builds from the Buildroot build process.
• Developer Experience: Provides a pre-configured environment, but integration with external build systems might require workarounds.
• Customization: Limited flexibility for integrating with existing build systems.
• Learning Curve: Relatively easy for basic usage.

Yocto Project

• Relevance for module development: While powerful for building components, Yocto should be used to configure existing build scripts (Makefiles, CMake) rather than directly building the module. This ensures the module remains independent.
• Developer Experience: Can be complex to integrate with external build systems due to its layered structure and BitBake.
• Customization: Highly customizable, but this can add complexity when integrating with existing build scripts.
• Learning Curve: Steep.

Bob the Builder

• Relevance for module development: Well-suited for building modules in isolated environments. You can define dependencies and trigger builds independently.
• Developer Experience: Modern approach with declarative configuration and containerization. Aims for ease of use and reproducibility.
• Customization: Offers a balance between flexibility and ease of use for integrating with existing build systems.
• Learning Curve: Moderate.

CMake/Make/Scripts

• Relevance for module development: The most direct and independent approach. You have full control over the build process and can easily integrate with any distribution.
• Developer Experience: Familiar tools for many developers, but requires manual configuration and scripting.
• Customization: Highly customizable.
• Learning Curve: Can range from moderate to steep.

Bazel

• Relevance for module development: Excellent for building complex projects with many dependencies. Strong support for hermetic builds and remote caching.
• Developer Experience: Can have a steeper learning curve, but offers powerful features and good performance.
• Customization: Highly customizable through BUILD files.
• Key Considerations: May require more effort to set up initially.

Meson

• Relevance for module development: Good for building C/C++ modules. Simpler syntax and faster build times compared to CMake.
• Developer Experience: Generally considered easier to learn and use than CMake.
• Customization: Provides good customization options.
• Key Considerations: Growing in popularity, but the community might not be as large as CMake's.

SCons

• Relevance for module development: Can be used to build C/C++ modules. Offers more flexibility than Make and integrates well with Python.
• Developer Experience: Python knowledge can be helpful.
• Customization: Highly customizable due to its Python foundation.
• Key Considerations: Not as widely used as CMake or Make.

PlatformIO

• Relevance for module development: Provides a simplified way to build modules for various embedded platforms. Can handle cross-compilation and dependencies.
• Developer Experience: User-friendly with good IDE support.
• Customization: Offers a good level of customization for embedded projects.
• Key Considerations: More focused on microcontroller-based platforms.

Custom Shell Scripts

• Relevance for module development: Provides maximum flexibility and control. You can use any tools and commands you need.
• Developer Experience: Requires good shell scripting knowledge.
• Customization: Completely customizable.
• Key Considerations: Best for simple modules or when you need very specific control.

Summary Table

Feature	Buildroot	Yocto	Bob	CMake/Make	Bazel	Meson	SCons	PlatformIO	Custom Scripts
Focus	Root filesystem	Component building	Streamlined builds	Code building	Complex builds	C/C++ modules	Flexible builds	Embedded ecosystem	Maximum control
Author/Origin	Peter Korsgaard	Yocto Project	Sony	Kitware (CMake)	Google	Jussi Pakkanen	Steven Knight	PlatformIO	N/A
Configuration	menuconfig	Layers/recipes	YAML	CMakeLists.txt, Makefiles	BUILD files	Meson files	Python scripts	PlatformIO config	Shell scripts
Build System	Makefile-based	BitBake	Docker	CMake/Make + custom	Bazel	Meson	SCons	PlatformIO	Custom
Customization	Limited	High	Balanced	High	High	Good	High	Good	Complete
Independent Builds	Requires effort	Configure, not build	Well-suited	Ideal	Excellent	Good	Good	Good	Ideal
Community	Active	Large	Growing	Massive	Growing	Growing	Moderate	Growing	N/A
Learning Curve	Moderate	Steep	Moderate	Moderate/Steep	Steep	Moderate	Moderate	Moderate	Moderate/Steep
Dev Experience	Less flexible	Complex	Modern	Familiar but manual	Powerful but steep	User-friendly	Python-based	User-friendly	Requires scripting
Strengths	Pre-configured	Dependency management	Reproducible builds	Flexibility	Hermetic builds	Speed, simplicity	Flexibility	Simplified workflow	Maximum control
Weaknesses	Not for modules	Overkill, integration	Relatively new	Can be complex	Initial setup	Community size	Less widely used	Microcontroller focus	Can be complex

Which one to choose (for developing code modules)?

• Quick cross-compilation with standard libraries: Buildroot (with adaptation)
• Manage complex dependencies, configure build scripts: Yocto (configure, not build)
• Modern, reproducible environment, good developer experience: Bob the Builder
• Flexibility, control, portability, comfortable with scripting: CMake/Make/Scripts
• Complex projects, hermetic builds, remote caching: Bazel
• User-friendly build system for C/C++ modules: Meson
• Flexibility and Python integration: SCons
• Simplified workflow for embedded platforms: PlatformIO
• Maximum control and customization: Custom Shell Scripts

Choosing the right tool depends on your module's complexity, your team's expertise, and your desired level of customization. Prioritize independent module builds to ensure portability and avoid unnecessary dependencies on the build framework.