The power of SystemReady for custom-built OS distributions

Emerging trends in the edge IoT space demand more robust OS capabilities to meet the increasingly complex use cases of the future edge computing landscape. As edge computing expands, OEMs, ODMs, and developers must address challenges related to platform interoperability, security, and scalability. To mitigate these challenges, Arm developed the SystemReady Devicetree band within the wider SystemReady program, which is aimed to ensure that operating systems and software stacks can seamlessly run across compliant Arm-based platforms. 
Note: when SystemReady is mentioned in this article it is always referring to the SystemReady Devicetree band.

SystemReady minimizes friction within the software ecosystem by enabling organizations to deploy their preferred OS and software stack on compliant systems with minimal customization. This results in faster time to market, reduced total cost of ownership, minimized platform-dependent issues within the supply chain, and increased scalability.

However, custom-built distributions as OpenWrt or Yocto are the preferred option for their lightweight, modular design and currently dominate the embedded Linux space. These distributions allow for a tailored software stack with a minimal memory footprint, ideal for competitive markets. Customizations offer clear benefits to the market, but it can compromise interoperability and can lead to significant technical debt for vendors and consumers alike. The SystemReady Devicetree band addresses these challenges, offering a path to sustainable and scalable Linux OS development, either it is a custom-built Linux OS, open-source Linux OS distribution or an enterprise-Linux OS distribution. 

Decoupling Firmware, Kernel, and Customization

One of the core principles behind the SystemReady Devicetree band is the clear separation between firmware, OS Kernel, and upper software layers. This differentiation allows for a more manageable development lifecycle while ensuring that system customization does not compromise interoperability or security.

• Firmware governs the boot process and presents hardware to the software.
• Kernel serves as the engine that drives the operating system and hardware interaction.
• Customizations should be applied at the upper software layers, above the kernel, ensuring they add value without compromising system integrity.

This separation ensures that customization happens where it matters most, in user space applications and specific functional packages, while the underlying system remains interoperable, updatable and secure. By focusing on software layers that do not disrupt the core firmware and kernel, organizations can enhance functionality and differentiation while maintaining the ability to integrate future updates and innovations with minimal friction.

The SystemReady Devicetree band offers advantages for custom-built OSes, addressing common challenges in maintaining and evolving custom-built systems:

1. Maintenance Overhead

Easiness of upgrading: compliance to SystemReady reduces the complexity of keeping customizations up to date. By promoting a clear separation between firmware, kernel, and customizations, it simplifies the process of integrating regular Linux kernel and proprietary firmware updates, which often include bug fixes, security patches, and new features. This streamlined approach eliminates the need to manually port deeply embedded changes, lightening the maintenance burden.

Upstream compatibility: In addition, customizations that are not aligned with upstream kernel or standardized firmware stacks may become incompatible with future versions. Compliance to SystemReady helps in terms of compatibility with upstream updates, helping to reduce long-term maintenance costs by allowing core firmware and kernel updates to be implemented without breaking the system.

2. Security Risks

Prompt Security Patches: One major benefit of compliance to SystemReady is the ability to apply critical security patches promptly, as compliant systems do not require extensive custom integrations. This helps reduce the risk of delayed security updates, which can leave systems vulnerable.

Reduced Attack surface: Moreover, compliance to SystemReady minimizes the risk of introducing security vulnerabilities through custom interfaces or kernel code. By using standardized, community-tested interfaces, it provides a more secure foundation that has undergone extensive validation.

3. Loss of Standardization

Interoperability: Custom kernel or firmware modifications may lead to interoperability issues with third-party applications, drivers, and hardware. Compliance to SystemReady helps that hardware and firmware conform to standardized interfaces, enabling smooth integration across various platforms and ecosystems, thereby reducing these issues.

Increased portability: Additionally, systems that rely on tightly coupled, proprietary configurations lack portability. Compliance to SystemReady promotes compatibility across different platforms, reducing the risk of vendor lock-in and increasing market flexibility.

4. Vendor Lock-in

Custom firmware and kernel configurations can lock a system into a particular vendor’s ecosystem, making it difficult and costly to switch. Compliance to SystemReady mitigates this risk by ensuring that standardized firmware and kernel interfaces remain consistent, allowing easier transitions between Arm-based platforms.

5. Performance Drops

Customizations aimed at optimizing performance for specific workloads can sometimes lead to unintended performance drops in other areas. Compliance to SystemReady reduces the likelihood of these regressions by ensuring that core system components are optimized for general use and performance across a wide range of scenarios.

6. Lack of Community Support

Custom OS builds that deviate from standard Linux and firmware architectures often lose support from the open-source community. By maintaining compatibility with community-supported ecosystems, Compliance to SystemReady ensures continued access to the wealth of resources and expertise offered by the open-source community.

7. Cost Implications

Developing custom firmware and kernel components requires specialized expertise, driving up both development and maintenance costs. Compliance to SystemReady helps reduce these expenses by allowing developers to focus on higher-level customizations, cutting down on the costs associated with low-level integrations.

8. Time to market

The added complexity of customizing core system components can also slow time to market. Compliance to SystemReady accelerates product launches by supporting the integration of well-tested, off-the-shelf components, streamlining the development process and reducing time to market.

What Arm Has Done for SystemReady to Support Custom-Built Linux OSes.

Arm is constantly working and investing in the open-source community to provide enabling technologies with UEFI and Devicetree capabilities, that is, adding UEFI features in relation to boot, security and maintenance services, security, and maintenance, while ensuring that the underlying boot flow remains platform-agnostic.

Arm has also made strides in supporting SystemReady for popular custom OS distributions. For example, a common target, "armsr", has been created for OpenWrt, allowing vendors to build SystemReady-compliant systems. This enables vendors to customize their software stack on top of a standardized kernel and interoperable baseline using the OpenWrt layering methodology.

For Yocto, Arm64 generic machine definition has been stripped out from the meta-arm which was occasionally conflicting to vendors recipes, and it has been incorporated into the Yocto core layer "meta-poky-bsp", simplifying the integration of SystemReady principles into custom builds.

What Vendors and Developers Must Do to Realize SystemReady’s Value.

Who benefits from SystemReady?

SystemReady's value proposition is clear for both vendors and systems integrators:

• Vendors seeking to offer products with multiple OS options, such as enterprise Linux distributions, openSource Linux distributions or custom-build Linux distributions, can maintain a unified firmware codebase. This approach reduces development overhead, enhances scalability, and simplifies system updates.
• Systems integrators benefit from refreshing their software stacks while ensuring long-term compatibility, scalability, and cost-efficiency, enabling them to meet evolving market demands without sacrificing flexibility.

Steps for Implementation:

1. Adhere to SystemReady Principles: Follow the defined interoperability guidelines to ensure consistent functionality, security, and compatibility across different platforms.
2. Upstream Contributions: Contribute custom code to upstream repositories to prevent fragmentation and reusability. By upstreaming, you reduce the maintenance burden and ensure ongoing compatibility with community-driven improvements.
3. Leverage the Arm Architecture Compliance Suite (ACS): Incorporate ACS into your CI or CD pipeline to continuously test and validate compliance with SystemReady standards, ensuring seamless and continuous updates smoothly.
4. Engage with SystemReady Communities: Collaborate with relevant groups such as the SystemReady Architecture Advisory Committee and the Embedded Base Boot Requirements (EBBR) communities to stay aligned with industry best practices and emerging standards, as well driving the standards moving forward.

Conclusion

SystemReady provides the framework to create scalable, secure, and maintainable custom OS distributions while ensuring interoperability. By following SystemReady principles, vendors and developers can reduce maintenance burdens, avoid vendor lock-in, enhance security, and improve time to market, all while building competitive and differentiated systems.

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