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Xenomai

Other · Runtime & Infrastructure

Xenomai

4.0 (EVL r58)

Active Open source Real-time capable API available
CATEGORYOther · Runtime & Infrastructure
READINESSTRL 8
ADOPTION SCALEProduction – Limited Deployment
LICENSESGPL-2.0-only
FIRST RELEASE2001

Xenomai is an open-source project providing hard real-time capabilities on Linux through a co-kernel (dual-kernel) technique. It historically derived from the RTAI (Real-Time Application Interface) project and is developed by a community in which CNRS and other research institutes play a significant role.

Xenomai 3 (Cobalt series) runs as a small co-kernel alongside the Linux kernel. The RT kernel (Cobalt) takes hardware interrupt priorities and handles real-time tasks directly, treating the standard Linux kernel as an idle task. Real-time applications communicate with Cobalt through the libcobalt library. Cycle latencies are typically 2–10 µs.

Xenomai 4 (EVL series) represents a new approach: instead of a co-kernel it uses the Dovetail interface – a lightweight Linux kernel integration layer introducing out-of-band scheduling without creating a separate co-kernel. EVL is closer in spirit to PREEMPT_RT while maintaining extremely low latencies.

In robotics, Xenomai is particularly used in France (LAAS-CNRS), ROS-Industrial, KUKA manipulators (via Fast Robot Interface), service and research robot control systems. It supports IgH EtherCAT Master as the cycle timer provider.

Documentation
Type & Roles
Software types
RTOS (real-time operating system)

Real-time operating system with a deterministic scheduler and guaranteed interrupt latency. Typically used in motion control, safety-critical systems, ADAS, and industrial robotics (VxWorks, QNX Neutrino, RT-Linux, Zephyr).

Operating system

General-purpose or robotics-specialized operating system — Ubuntu, Ubuntu Core, ROS-aware distributions. Provides the platform for middleware, runtime, and robotic applications.

Select an item to see its description.
Main category
Runtime & InfrastructureDrivers & Firmware
Roles in robotics ecosystem
Robot Control
Software family
Family

Family of tools providing hard real-time capabilities in Linux and EtherCAT fieldbus communication – the foundation of industrial and robotic low-level control.

Maturity & Adoption
8 / 9
Prototype / pilot phase
ResearchPrototypeProduction
Adoption scaleProduction – Limited Deployment
Maintenance statusActively Maintained
First release2001
Last update1 October 2024
Deployments

KUKA Fast Robot Interface (FRI), LAAS-CNRS systems, research manipulators requiring < 1 ms latency, integration with IgH EtherCAT.

Community

Several hundred active users, mailing list, GitLab, strong presence in European academic environments.

Organizations
Integrates with
IE
IgH EtherCAT Master
Open-source EtherCAT master for Linux by IgH GmbH – supports hard real-time with PREEMPT_RT or Xenomai and is deployed in thousands of industrial and robotic projects worldwide.
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R2
ROS 2
Open-source framework for building robot software. The successor to ROS 1, built on DDS with native support for distributed, real-time and multi-platform systems. The de facto standard in research and commercial robotics.
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R2
ROS 2 Humble Hawksbill
LTS release of the ROS 2 framework based on Ubuntu 22.04, supported through May 2027. The most widely deployed release in humanoids, AMRs, and research platforms. Full integration with Nav2, MoveIt 2 and ros2_control.
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Related robotics software
IE
IgH EtherCAT Master
Open-source EtherCAT master for Linux by IgH GmbH – supports hard real-time with PREEMPT_RT or Xenomai and is deployed in thousands of industrial and robotic projects worldwide.
→
P
PREEMPT_RT
PREEMPT_RT patch transforms the standard Linux kernel into a hard real-time system, reducing interrupt latencies to microseconds – a cornerstone of robot motion control stacks worldwide.
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Target robotic platforms
Industrial Robot
Robotic Arm
Research Robot
Humanoid
Mobile Robot
ROS supportCompatibility with ROS / ROS 2 ecosystem
Community ROS 2 WrapperWrapper ROS 2 tworzony i utrzymywany przez społeczność, nie przez producenta
Community ROS 1 WrapperWrapper ROS 1 tworzony i utrzymywany przez społeczność
System capabilities
⊙
Open source
Source code is publicly available under an open-source license — enables security audits, custom modifications, and integration without licensing barriers.
✓
⚡
Real-time capable
Designed with timing-determinism guarantees — meets the requirements of control loops, safety systems, and tasks demanding low, predictable latency.
✓
⟨/⟩
API available
The software exposes a programmable interface (REST, gRPC, SDK, or language bindings) that enables automation and integration with other systems.
✓
📦
Pre-built / binary
Distributed as ready-to-use binary packages, container images, or installers — no need to build from source.
✓
Programming languages
CC++
Operating systems
Ubuntu 20.04Ubuntu 22.04Debian
Ubuntu 24.04

Ubuntu 24.04 LTS 'Noble Numbat' — supported until April 2029. The host for ROS 2 Jazzy.

Select an item to see its description.
Minimum hardware requirements
Packaging & distribution
Package managers
apt / debSource – CMake / ament_cmake
CPU architectures
x86_64 (AMD64)ARM64 / AArch64aarch64 / ARM64ARMv7 / ARM32 (armhf)x86 (32-bit / i386)
Installation difficulty
LevelExpert only
Protocols and interfaces
Communication protocols
EtherCATCAN bus (Controller Area Network)CAN FD (CAN with Flexible Data-Rate)Ethernet / TCP-IP
Hardware interfaces
Ethernet 1000BASE-T (Gigabit Ethernet)Ethernet 100BASE-TX (Fast Ethernet)EtherCAT (Slave Interface)CAN 2.0A / 2.0BCAN FD (Flexible Data-Rate)
Latency classes
Hard Real-Time (< 1 ms)Hard Real-Time (1–5 ms)
Licenses
GPL-2.0-onlyGNU General Public License v2.0v2.0

License family: Strong Copyleft

ModificationDistributionCommercial usePrivate useOSI approvedFSF Free/LibreRequires attributionShare-alikeSource disclosure
Official text ↗SPDX ↗OSI ↗
LGPL-2.1-onlyGNU Lesser General Public License v2.1v2.1

License family: Weak Copyleft

ModificationDistributionCommercial usePrivate useROS-compatibleOSI approvedFSF Free/LibreRequires attributionShare-alikeSource disclosure
Official text ↗SPDX ↗OSI ↗
Version history
4.0 (EVL r58)Oct 2024

EVL r58 – Dovetail interface, no co-kernel, arm64 support.

3.3.3Jun 2024

Cobalt LTS – stable branch for production systems.

3.1Jan 2018

Introduction of the Cobalt dual-kernel architecture.