Biblio

Creating and implementing fault-tolerant distributed algorithms is a challenging task in highly safety-critical industries. Using formal methods supports design and development of complex algorithms. However, formal methods are often perceived as an unjustifiable overhead. This paper presents the experience and insights when using TLA+ and PlusCal to model and develop fault-tolerant and safety-critical modules for TAS Control Platform, a platform for railway control applications up to safety integrity level (SIL) 4. We show how formal methods helped us improve the correctness of the algorithms, improved development efficiency and how part of the gap between model and implementation has been closed by translation to C code. Additionally, we describe how we gained trust in the formal model and tools by following a specific design process called property-driven design, which also implicitly addresses software quality metrics such as code coverage metrics.

This paper discusses strategies for I/O sharing in Multiple Independent Levels of Security (MILS) systems mostly deployed in the special environment of avionic systems. MILS system designs are promising approaches for handling the increasing complexity of functionally integrated systems, where multiple applications run concurrently on the same hardware platform. Such integrated systems, also known as Integrated Modular Avionics (IMA) in the aviation industry, require communication to remote systems located outside of the hosting hardware platform. One possible solution is to provide each partition, the isolated runtime environment of an application, a direct interface to the communication's hardware controller. Nevertheless, this approach requires a special design of the hardware itself. This paper discusses efficient system architectures for I/O sharing in the environment of high-criticality embedded systems and the exemplary analysis of Free scale's proprietary Data Path Acceleration Architecture (DPAA) with respect to generic hardware requirements. Based on this analysis we also discuss the development of possible architectures matching with the MILS approach. Even though the analysis focuses on avionics it is equally applicable to automotive architectures such as Auto SAR.