| Zephyr | |
|---|---|
 Zephyr Project logo | |
| Developer | Linux Foundation, Wind River Systems |
| Written in | C |
| OS family | Real-time operating systems |
| Working state | Current |
| Source model | Open source |
| Initial release | 26 July 2016; 8 years ago (2016-07-26)[1] |
| Latest release | 4.1.0 / 7 March 2025; 4 months ago (2025-03-07)[2][3] |
| Repository | |
| Marketing target | Internet of things,Embedded Systems |
| Available in | English |
| Instruction sets | ARM (Cortex-M,Cortex-R,Cortex-A),ARC,MIPS,Nios II,RISC-V,Xtensa,SPARC,x86,x86-64 |
| Kernel type | Microkernel (pre-v1.6)[4][5][6] Monolithic (v1.6+)[5][6] |
| License | Apache 2.0 |
| Preceded by | Wind River Rocket |
| Official website | www |
Zephyr (/ˈzɛfər/) is a smallreal-time operating system (RTOS)[7] for connected, resource-constrained andembedded devices (with an emphasis onmicrocontrollers) supporting multiple architectures and released under theApache License 2.0. Zephyr includes akernel, and all components andlibraries,device drivers,protocol stacks,file systems, andfirmware updates, needed to develop fullapplication software.[8]
It is named afterZephyrus, the ancient Greek god of the west wind.[9]
Zephyr originated from Virtuoso RTOS fordigital signal processors (DSPs).[10][11] In 2001,Wind River Systems acquired Belgian software company Eonic Systems, the developer of Virtuoso. In November 2015, Wind River Systems renamed theoperating system toRocket, made it open-source and royalty-free.[11] Compared to Wind River's other RTOS,VxWorks, Rocket had much smaller memory needs, especially suitable for sensors and single-function embedded devices. Rocket could fit into as little as 4 KB of memory, while VxWorks needed 200 KB or more.[11]
In February 2016, Rocket became a hosted collaborative project of theLinux Foundation under the nameZephyr.[10][12][1] Wind River Systems contributed the Rocket kernel to Zephyr, but still provided Rocket to its clients, charging them for the cloud services.[13][11] As a result, Rocket became "essentially the commercial version of Zephyr".[13]
Since then, early members and supporters of Zephyr includeIntel,NXP Semiconductors,Synopsys,Linaro,[14]Texas Instruments,Nordic Semiconductor,Oticon, andBose.[15]
As of January 2025[update], Zephyr had the largest number of contributors and commits compared to other RTOSes (includingMbed,RT-Thread,NuttX, andRIOT).[16]
Zephyr intends to provide all components needed to develop resource-constrained and embedded or microcontroller-based applications. This includes, but is not limited to:[8]
Zephyr usesKconfig anddevicetree as its configuration systems, inherited from theLinux kernel but implemented in the programming languagePython for portability to non-Unix operating systems.[17] The RTOS build system is based onCMake, which allows Zephyr applications to be built onLinux,macOS, andMicrosoft Windows.[18]
Zephyr has a general-purpose tool called "west" for managing repositories, downloading programs to hardware, etc.
Early Zephyr kernels used a dualnanokernel plus microkernel design.[4][5][6] In December 2016, with Zephyr 1.6, this changed to amonolithic kernel.[5][6]
The kernel offers several features that distinguish it from other small OSes:[8]
A group is dedicated to maintaining and improving the security.[19] Also, being owned and supported by a community means the world's open source developers are vetting the code, which significantly increases security.[12]
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