Open Source Summit Europe 2022

Embedded processors are increasingly equipped with powerful CPU cores. For mixed-criticality scenarios with multiple independent real-time appliances, this allows us to consolidate formerly distributed systems. This requires absence of unintended interaction between different computing domains, which can be achieved by exploiting virtualisation extensions of modern CPUs. Though providing strong isolation guarantees, virtualisation comes with an overhead, which may endanger global real-time properties of the system. The statically partitioning, Linux-based hypervisor Jailhouse addresses this challenge and strives at zero-overhead virtualisation, which maintains real-time capabilities of the platform by design. However, limitations of current architectures counter our architectural design goal of eliminating virtualisation overheads. In this talk, we extract architecture-independent common requirements on contemporary platforms to enable zero-trap virtualisation. We explore and compare the ARM, x86, and the RISC-V architecture, and inspect their architectural limitations for embedded zero-overhead virtualisation. We present common pitfalls and barriers of those platforms: Issues that have been addressed, that are being fixed and that need to be addressed in future.
With additional contributions from Wolfgang Mauerer, OTH Regensburg / Siemens AG.