Real-time OS in Linux Foundation

Linux is a successful open-source project also in embedded devices for medical, telecom, industry, and automotive solutions. Linux gives developers a rich set of features and tools that can be used during design, development and debugging. Designing a system that requires hard real-time and/or safety-critical systems is challenging using Linux. For these types of systems, Linux Foundation has launched Zephyr designed to support resource-constrained devices with hard real-time requirements.

In 2016 the Zephyr project was started as a project under Linux Foundation and WindRiver contributed the kernel source as an initial code base. Already from the beginning, the code was distributed as open source under the Apache 2.0 license. In August 2020 Zephyr had the largest number of contributors and commits compared to other open-source RTOSes and the member list contains companies like Intel, Google, NXP and Nordic Semiconductor.

Zephyr is a complete stack including the kernel with multi-threading, interrupt handling and inter-thread synchronization. On top, there are several communication stacks including TCP/IP and Bluetooth Low Energy (BLE). The kernel supports most modern CPU architectures and there are almost 400 boards available in GitHub. Being the little brother of Linux the Zephyr project also inherits some well-established concepts like Kconfig format for kernel configuration, Device Tree solution for the loading and access of the hardware drivers. All in all, there are more than 50 submodules that can be used with Zephyr and all can be downloaded as source code directly from GitHub.

The Zephyr project has also inherited the extensive security process used in the original Linux project and today it has its own security subcommittee. The tasks of the committee span from supervising the design of new sub-modules regarding threats and countermeasures and securing the development with processes and relevant coding principles and other quality measures. There is also a maintained security vulnerability list maintained by the project that is accessible for eligible members.

In the beginning of 2021, the Zephyr project announced that it starts a work group to create the necessary tools and documents to give members the possibility to certify Zephyr according to the safety standard IEC 61508 and its sub-standards for Automotive-, Machinery-, Nuclear- and Rail-industries.