# Zephyr RTOS Addressing Common Criticisms > [! note]- > The content of this page is generated by audio/video transcription and text transformation from the content and links of this source. Source: [https://fosdem.org/2025/schedule/event/fosdem-2025-5760-zephyr-rtos-roasting-party/](https://fosdem.org/2025/schedule/event/fosdem-2025-5760-zephyr-rtos-roasting-party/) <video src="https://video.fosdem.org/2025/h1302/fosdem-2025-5760-zephyr-rtos-roasting-party.av1.webm" controls></video> ## Summary & Highlights: The Zephyr RTOS Roasting Party at FOSDEM 2025 is a session aimed at addressing common criticisms of the Zephyr real-time operating system. Hosted by Benjamin Cabé, the session explores the challenges and opportunities of using Zephyr in embedded systems. Key topics include its perceived bloat, real-time performance, and complexity of tools like Devicetree and West. **Introduction to Zephyr RTOS** Zephyr RTOS, an open-source project, celebrated its 10th anniversary with significant community contributions. It has evolved beyond a simple RTOS into a comprehensive framework for hardware abstraction, connectivity, and development. Despite its growth, Zephyr faces criticism for being bloated and complex. **Common Criticisms** Critics argue that Zephyr is too large and slow, with excessive hardware abstraction layers. The Devicetree tool is often seen as overly complex, and the necessity of the West tool is questioned. These criticisms are addressed by highlighting Zephyr's configurability and the benefits of its comprehensive setup. **Zephyr's Benefits and Challenges** While Zephyr may seem bloated, it offers a robust environment for developing complex applications. Its default configurations prioritize security and developer experience, but users can customize settings for performance. The session encourages understanding Zephyr's design decisions to better leverage its capabilities. **Practical Applications and Future Directions** Through practical demos, the session illustrates how Zephyr's tools can streamline development. Participants learn to navigate its complexities and apply Zephyr effectively in their projects. The session also discusses the roadmap for future improvements, inviting community input. ## Importance for an eco-social transformation Zephyr RTOS plays a significant role in eco-social transformation by promoting open-source collaboration and innovation in embedded systems. Its comprehensive framework supports sustainable development through efficient resource use and hardware abstraction, enabling diverse applications from smart devices to renewable energy systems. Eco-social designers can leverage Zephyr's tools to create solutions that address social and environmental challenges. However, the complexity of tools like Devicetree and West can be barriers to entry, requiring community support and documentation to overcome. Sustainable and ethical issues include ensuring accessibility and inclusivity in technology development, fostering community-driven innovation, and addressing the environmental impact of hardware production. ## Slides: | | | | --- | --- | | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_001.jpg\|300]] | The first slide introduces the session, titled 'Zephyr RTOS Roasting Party,' presented by Benjamin Cabé at FOSDEM 2025. The session aims to discuss the strengths and weaknesses of Zephyr RTOS in an open and honest manner. | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_002.jpg\|300]] | The second slide provides background information on Benjamin Cabé, the session's speaker. He is a Developer Advocate for the Zephyr Project with nearly 20 years of experience in open source and IoT. Despite not being an embedded developer 'veteran,' he brings a wealth of knowledge and diverse interests, including baking, pottery, and photography. | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_003.jpg\|300]] | The third slide offers an overview of Zephyr RTOS, highlighting its open-source nature under the Apache License since 2015. It boasts over 140 maintainers, 2,500 contributors, and 109,478 commits. Zephyr scales from small microcontrollers to complex systems-on-chip, demonstrating its versatility and wide adoption. | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_004.jpg\|300]] | The fourth slide outlines the various facets of Zephyr, describing it as a real-time operating system, an über-HAL (Hardware Abstraction Layer), an embedded application framework, a connectivity framework, and a development environment. This broad functionality underscores Zephyr's comprehensive approach to embedded systems development. | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_005.jpg\|300]] | The fifth slide lists several products that utilize Zephyr RTOS, including Oticon hearing aids, the Framework laptop's embedded controller, the Samsung Galaxy Ring, and the Gardena radio gateway. These examples illustrate Zephyr's applicability across diverse industries and product types. | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_006.jpg\|300]] | The sixth slide explains the purpose of the 'roasting party,' acknowledging that while Zephyr is a beloved project, it is not without its flaws. The session aims to transparently address these issues while offering solutions and highlighting the project's potential. | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_007.jpg\|300]] | The seventh slide outlines common criticisms of Zephyr, such as its size, speed, and complexity. It addresses concerns about the necessity of hardware abstraction layers (YAHAL), the difficulty of using Devicetree for embedded systems, and the requirement to use the West tool. | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_008.jpg\|300]] | The eighth slide focuses on the criticism that Zephyr is too large. It emphasizes the importance of understanding the setup process and selectively enabling only the necessary modules to streamline the development environment. | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_009.jpg\|300]] | The ninth slide provides a step-by-step guide to setting up a local workspace for Zephyr development. It highlights the simplicity of initializing the workspace, fetching modules, and building a sample application using the West tool. | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_010.jpg\|300]] | The tenth slide presents a breakdown of the disk usage within the Zephyr project directory, illustrating the significant storage space required by various components, including bootloaders, modules, tools, and the Zephyr core. | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_011.jpg\|300]] | The eleventh slide details the storage space consumed by different hardware abstraction layers (HAL) within the Zephyr project. It lists the disk usage for various HAL modules, such as those from ADI, Altera, Ambiq, Atmel, Espressif, and Xtensa. | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_012.jpg\|300]] | The twelfth slide outlines the storage requirements for different toolchains within the Zephyr SDK. It includes disk usage for architectures like aarch64, arc, arm, and xtensa, highlighting the substantial space needed for comprehensive development support. | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_013.jpg\|300]] | The thirteenth slide summarizes the total disk usage of the Zephyr SDK, emphasizing its size of 8.2 GB. This serves as a reminder of the extensive resources required for a complete Zephyr development environment. | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_014.jpg\|300]] | The fourteenth slide addresses the question of why such a large amount of data is necessary for simple tasks like blinking an LED. It suggests focusing on enabling only the required modules and using the West manifest to streamline the development environment. | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_015.jpg\|300]] | The fifteenth slide reiterates the criticism that Zephyr is bloated, emphasizing the need for users to customize their development environment to suit their specific needs and avoid unnecessary complexity. | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_016.jpg\|300]] | The sixteenth slide highlights the various aspects of Zephyr's performance, including real-time performance, memory footprint, developer experience, security, hardware abstraction, configurability, power efficiency, and connectivity. These factors contribute to Zephyr's versatility and adaptability. | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_017.jpg\|300]] | The seventeenth slide further explores the aspects of Zephyr's performance, reinforcing the importance of balancing different performance metrics to achieve optimal results in embedded systems development. | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_018.jpg\|300]] | The eighteenth slide continues to discuss Zephyr's performance aspects, emphasizing the trade-offs between different performance metrics and the need for customization to meet specific application requirements. | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_019.jpg\|300]] | The nineteenth slide reiterates the performance aspects of Zephyr, highlighting the importance of considering real-time performance, memory footprint, and other factors when selecting an RTOS for a given application. | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_020.jpg\|300]] | The twentieth slide explains that Zephyr's default options are intended as a starting point. It notes that hardware stack protection is enabled by default, optimization is geared towards size rather than speed, and some defensive programming patterns are on by default. | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_021.jpg\|300]] | The twenty-first slide advises caution when interpreting benchmarks, noting that Zephyr is not fine-tuned out-of-the-box. It emphasizes that the actual application and use case should drive the RTOS selection process, rather than relying solely on benchmark results. | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_022.jpg\|300]] | The twenty-second slide questions the use of Devicetree for embedded systems, acknowledging the skepticism around its complexity and applicability in the embedded context. | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_023.jpg\|300]] | The twenty-third slide explains the role of Devicetree in Zephyr, highlighting its use for describing hardware and providing initial configuration at compile-time. This approach facilitates hardware abstraction and integration. | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_024.jpg\|300]] | The twenty-fourth slide provides an example of Devicetree usage in Zephyr, illustrating how hardware components like I2C buses and sensors are configured and described within the system. | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_025.jpg\|300]] | The twenty-fifth slide revisits the role of Devicetree in Zephyr, emphasizing its importance in hardware description and configuration within the embedded development framework. | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_026.jpg\|300]] | The twenty-sixth slide showcases a code snippet demonstrating how Devicetree is used in Zephyr to obtain device references, highlighting the practical application of this tool in embedded systems development. | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_027.jpg\|300]] | | | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_028.jpg\|300]] | The twenty-eighth slide addresses the challenges of using Devicetree macros in Zephyr, acknowledging the potential for errors and the complexity of troubleshooting issues related to missing or disabled nodes. | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_029.jpg\|300]] | The twenty-ninth slide offers guidance on troubleshooting Devicetree-related errors in Zephyr, distinguishing between compiler and linker errors and providing resources for resolving common issues. | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_030.jpg\|300]] | The thirtieth slide expresses the sentiment of not wanting to use the West tool, acknowledging user preferences for alternative build systems while highlighting the benefits of West in simplifying development tasks. | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_031.jpg\|300]] | The thirty-first slide describes West as Zephyr's 'Swiss Army knife,' detailing its capabilities in module management, building, flashing, debugging, and static code analysis. It emphasizes West's extensibility and convenience in the development process. | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_032.jpg\|300]] | The thirty-second slide reassures users that using West is optional, noting that traditional build systems like CMake and Ninja can be used instead, albeit with potential challenges and less convenience. | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_033.jpg\|300]] | The thirty-third slide addresses concerns about unsupported boards or sensors, encouraging contributions to the open-source project and highlighting the community-driven nature of Zephyr development. | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_034.jpg\|300]] | The thirty-fourth slide invites further discussion and feedback from the audience, encouraging engagement and collaboration to address outstanding issues and improve the Zephyr project. | ![[FOSDEM 2025/assets/Zephyr-RTOS-Roasting-Party/preview_035.jpg\|300]] | The thirty-fifth slide concludes the presentation, providing contact information for Benjamin Cabé and promoting the Zephyr project website. It invites attendees to visit the Zephyr table at FOSDEM 2025 for further engagement. ## Links [Zephyr Project - GitHub](https://github.com/zephyrproject-rtos) [Zephyr Project - Documentation](https://docs.zephyrproject.org) [Video recording (AV1/WebM) - 97.0 MB](https://video.fosdem.org/2025/h1302/fosdem-2025-5760-zephyr-rtos-roasting-party.av1.webm) [Video recording (MP4) - 545.5 MB](https://video.fosdem.org/2025/h1302/fosdem-2025-5760-zephyr-rtos-roasting-party.av1.mp4) [Video recording subtitle file (VTT)](https://video.fosdem.org/2025/h1302/fosdem-2025-5760-zephyr-rtos-roasting-party.vtt) [Chat room(web)](https://fosdem.org/2025/chat/h1302) [Chat room(app)](https://fosdem.org/2025/chat/app)