BayLibre partners with Arm to bring Zephyr OS support to Armv9 Cortex-A processors

Bringing Cortex-A320 capabilities to real-time systems

BayLibre is proud to announce its successful collaboration with Arm to enable foundational Real-Time Operating System (RTOS) support with Zephyr OS support for the Armv9.2-A architecture. The focus is on the Cortex-A320 processor; the smallest Armv9 implementation designed to support both real-time and rich operating systems.

Empowering Edge AI with RTOS alternatives

Arm has invested in expanding RTOS support across its Cortex-A portfolio to boost Edge AI capabilities and give device makers more system design options.

Zephyr is a flexible operating system with a small footprint and a strong open-source community, which makes it a good choice for this initiative. BayLibre was selected as Arm’s trusted partner to deliver this enablement upstream, based on its proven expertise and long-standing role as a key Zephyr contributor.

Armv9-A enablement in Zephyr

This collaboration focused on establishing foundational Armv9-A support in Zephyr, with emphasis on advanced processor features that differentiate this latest generation.

Armv9-A architecture support

Explicit Armv9-A support was added to Zephyr arm64 architecture, with validated configurations for Cortex-A510 and Cortex-A320 processors.

Scalable Vector Extension (SVE / SVE2) context management

Zephyr implements comprehensive SVE context switching with an intelligent lazy context preservation mechanism. This approach lets applications use advanced SIMD capabilities efficiently and reduces context switching overhead.

Unified Fixed Virtual Platform (FVP) support

The Fixed Virtual Platform board infrastructure was reworked and unified to support both Armv8-A and Armv9-A configurations, including:
• Single-core systems
• SMP configurations
• Trusted Firmware-A (TF-A)–based setups.

SMP stability improvements

Multiple SMP-related issues were identified and resolved across both arm64-specific code and shared kernel components. This improved multi-core correctness and robustness across platforms.

Comprehensive testing and validation

An extensive validation suite was developed, including:
• SVE context switching tests across privilege levels
• SIMD stress testing
• Comprehensive architecture feature detection

All work was validated using the Arm Architecture Envelope Models Fixed Virtual Platform (AEM FVP) and reflects real-world deployment scenarios.

Successfully merged into Zephyr mainline

All implemented features have been merged into the Zephyr Project mainline, making them immediately available to the wider open-source community. You can find implementation details in Zephyr Pull Request #96852.

Looking ahead

This milestone marks the beginning of this work. Thanks to the ongoing partnership between Arm and BayLibre, additional Armv9-specific enablement work is already under development in Zephyr. We will share more updates as this work expands real-time capabilities on modern Arm architectures.

Key links

• BayLibre website
• Cortex-A320 Arm product page
• Architecture Envelope Models (AEM) FVP download page
• Zephyr Pull Request #96852 page: ARMv9-A support
• Zephyr documentation page: Armv9-A support on Arm Fixed Virtual Platforms (FVPs)
• Zephyr SVE stress test page: ARM64 Neon / SVE2 SIMD Context Switch stress test

Points of contact

Arm
Zineb Labrut
Software Product Owner, Edge AI Business Unit
Email: zineb.labrut@arm.com 

BayLibre
Email: contact@baylibre.com