Zephyr (operating system)

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DeveloperLinux Foundation,
Wind River Systems
Written inC and assembly
OS familyReal-time operating systems
Working stateCurrent
Source modelOpen source
Initial release17 February 2016; 2 years ago (2016-02-17)[1]
Latest release1.13.0 / 10 September 2018; 57 days ago (2018-09-10)[2]
Latest preview1.13.99 / 10 September 2018; 57 days ago (2018-09-10)
Marketing targetInternet of things
Available inEnglish
PlatformsARM (Cortex-M0, Cortex-M3, Cortex-M4, Cortex-M23, Cortex-M33), x86, ARC, RISC-V, Nios II, Xtensa
Kernel typeMonolithic
LicenseApache 2.0
Preceded byWind River Rocket
Official websitewww.zephyrproject.org

Zephyr is a small real-time operating system[3] for connected, resource-constrained devices supporting multiple architectures and released under the Apache License 2.0. A BSD licensed fork occurs in the Arduino 101 software source package from Intel.[4]


In November 2015, it was originally developed as Rocket[5][6][7] kernel by Wind River Systems for Internet of things (IoT) devices.[8]

In February 2016, Zephyr became a project of the Linux Foundation.[9][1]

Since then, early members and supporters of Zephyr include Intel, NXP Semiconductors, Synopsys, Linaro[10], runtime.io, DeviceTone, Nordic Semiconductor and Oticon.[11]


The Zephyr kernel is small and designed for use on resource-constrained systems: from simple embedded environmental sensors and light emitting diode (LED) wearables to sophisticated smart watches and IoT wireless gateways.

The kernel offers several features that distinguish it from other small OSes:

  • Single address-space
  • Highly configurable
  • Resources defined at compile-time
  • Minimal error checking
  • Development services


A group is dedicated to maintaining and improving the security.[12] Also being owned and supported by a community means the eyes of the world's open source developers are vetting the code, which significantly increases Zephyr security.[9]

Single address-space[edit]

Combines application-specific code with a custom kernel to create a monolithic image that gets loaded and executed on a system’s hardware. Both the application code and kernel code execute in one shared address space.

Highly configurable[edit]

Allows an application to incorporate only the abilities it needs, as needed, and to specify their quantity and size.

Resources defined at compile-time[edit]

Requires all system resources be defined at compile time, which reduces code size and increases performance.

Minimal error checking[edit]

Provides minimal run-time error checking to reduce code size and increase performance. An optional error-checking infrastructure is provided to assist in debugging during application development.

Development services[edit]

The development services offer several familiar services for development, including:

  1. Multi-threading services for both priority-based, non-preemptive cooperative threads and priority-based, preemptive threads with optional round robin time-slicing.
  2. Interrupt services for both compile-time and run-time registration of interrupt handlers.
  3. Inter-thread synchronization services for binary semaphores, counting semaphores, and mutex semaphores.
  4. Inter-thread data passing services for basic message queues, enhanced message queues, and byte streams.
  5. Memory allocation services for dynamic allocation and freeing of fixed-size or variable-size memory blocks.
  6. Power management services such as tickless idle and an advanced idling infrastructure.

See also[edit]


  1. ^ a b Zephyr Project: The Linux Foundation Announces Project to Build Real-Time Operating System for Internet of Things Devices, Linux Foundation, 17 February 2016
  2. ^ "Zephyr v1.13.0".
  3. ^ "Meet Linux's little brother: Zephyr, a tiny open-source IoT RTOS". LinuxGizmos.com. 2016-02-17. Retrieved 2018-02-23.
  4. ^ Zephyr Kernel v1.0.0 Release Notes
  5. ^ "MCU Commercial Free RTOS for small embedded edge devices | Rocket". windriver.com. Retrieved 2018-02-23.
  6. ^ "Wind River Sets Rocket RTOS On Free Trajectory – EEJournal". www.eejournal.com. Retrieved 2018-02-23.
  7. ^ https://software.intel.com/en-us/iot/rocket
  8. ^ Niheer Patel: Wind River Welcomes Linux Foundation’s Zephyr Project, Wind River Systems, 17 February 2016
  9. ^ a b Guerrini, Federico (2016-02-19). "The Internet of Things Goes Open Source with Linux Foundation's Zephyr Project". Forbes. Retrieved 2017-01-12.
  10. ^ Osborne, Charlie (2016-02-19). "The Linux Foundation's Zephyr Project: A custom operating system for IoT devices". ZDNet. CBS Interactive. Retrieved 2017-01-12.
  11. ^ ""Zephyr Project Members"".
  12. ^ Wallen, Jack (2016-02-18). "Linux Foundation announces Zephyr Project, an open source IoT operating system - TechRepublic". TechRepublic. CBS Interactive. Retrieved 2017-01-12.

External links[edit]