Smart Object Oriented (SO3) Operating System

SO3 is a compact, lightweight, full-featured and extensible operating system, particularly well suited to embedded systems. From a single code base it can be built in three ways:

as a standalone OS running directly on the hardware (EL1 on ARM64);
as the AVZ hypervisor (Agency VirtualiZer) running at EL2, hosting a single guest at EL1;
as an SO3 capsule (S3C) — a lightweight guest on top of AVZ, as part of the SOO framework.

_images/so3_modes.png — Fig. 1 The same SO3 code base deployed in its three modes.

The AVZ guest is the agency, which owns the hardware. The agency is normally Linux (and, with the SOO framework, runs SO3 capsules beside it); the SO3 tree can also be built as a plain guest (CONFIG_SOO=n) to exercise the hypervisor on its own.

This documentation reflects the current state of the code base: ARM 32/64-bit, multicore, the AVZ hypervisor and SO3 capsules are all supported.

Where to start

Introduction: Philosophy, history and the polymorphic nature of SO3.
Architecture · Kernel internals: The user/kernel split, the boot flow, and how the kernel subsystems work.
AVZ hypervisor · SO3 capsules: Virtualization at EL2 and the SOO capsule framework.
Build system · User guide: How the tree is built, configured and packaged, and a step-by-step setup.
User space · Debugging: The MUSL-based user land, and how to debug SO3 under QEMU/GDB or JTAG.

Acknowledgements

We would like to thank our sponsors for their generous support in funding the development of the SO3 ecosystem, especially HEIG-VD and the Hasler Foundation.

We are also grateful to all the contributors — developers, students, researchers and community members alike — whose code, ideas and feedback have shaped SO3.