A Modular Safety Case for an IEC 61508 Compliant Generic COTS Processor

The transition from conventional federated architectures to integrated architectures enables integration of functionalities with different criticality levels (e.g., SIL1-4 according to IEC-61508) on the same computing embedded platform. These systems, also called mixed-criticality systems, provide benefits in terms of cost, size, weight, reliability and scalability. However, mixed-criticality systems are subject to rigorous certification processes, which can lead to prohibitive cost. This paper contributes with a generic modular safety concept of an IEC-61508 compliant generic multicore COTS device where the minimum reasonable safety arguments and evidences are defined. Furthermore, the use of the modularity approach limits the impact of changes to a reduced area of the safety case, thus allowing the reusability of its parts. Additionally, this approach enables decoupling the safety arguments of subsystems with different criticality levels (e.g., SIL1-4 according to IEC-61508). The work described in this paper has been reviewed and approved by a certification body, within the context of an European research project.