Functional safety and variability: can it be brought together?

Today's product development creates multiple products over time, often by using reuse strategies like "Clone and Own", leading to very inefficient reuse of artifacts in the long term since synergy effects between the products e.g. from testing cannot be utilized. Applying a product line approach with explicitly modeling the commonalities and variabilities of system artifacts and deriving products from that common base is a way to tackle the problem. High variant complexity can often be found in the development of embedded systems, which in turn often control safety critical functions. For these systems functional safety is a major concern not only since the ISO 26262 got relevant for the automotive industry. The arising question is: Can variability in functional safety related assets be treated in the same way as for other artifacts like requirements, models, and source code? In this paper we demonstrate on the example of two commercial tools and an automotive use case that from the technical/tool point of view safety related artifacts can be treated like other artifacts regarding variability. This means linking with variability information and visualizing as well as deriving of variants is feasible. This is a big step forward, because now not only ordinary artifacts but also functional safety related assets can be reused in the same way as other product line artifacts. However, we have identified and will discuss challenges with respect to variable safety analyses, regulations, and reuse of certifications, which need further research and elaboration, in this paper.