Tool Integration, from Tool to Tool Chain with ISO 26262 2012-01-0026
The use of innovative power sources in future cars has long-ranging implications on vehicle safety. We studied these implications in the context of the guidance on software tool qualification in the then current ISO 26262 draft, when building an urban concept vehicle to participate in the 2011 Shell Eco-Marathon. While the guidance on tool qualification is detailed, the guidance in regard to tools integrated into tool chains is limited. It only points out that the environment that tools execute in needs to be taken into consideration.
In this paper we clarify the implications of tool chains on tool qualification in the context of ISO 26262 by focusing on answering two questions; first, are there parts of the development environment related to tool integration that are likely to fall outside of tool qualification efforts as currently defined by ISO 26262; secondly, can we define if, and -if so- how, tool integration is affected by ensuring functional safety.
We conclude by identifying two areas related to tool integration that are likely to fall outside the tool qualification efforts (data integrity and process logic) and describing how different constraints imposed by ISO 26262 in relation to tool qualification conflict when tool integration is improved (improvements aimed at supporting completeness, consistency and the safety lifecycle vs. tool qualification cost).
We are able to make additional conclusions in relation to the State of the Art discussion on software tool qualification according to ISO 26262. First, reference tool chains and guidelines on which characteristics tool qualification should ensure for tool chains are needed to complement ISO 26262. Secondly, guidance on tool integration can be found in the completeness characteristic, the consistency characteristic and the ISO 26262 safety lifecycle process. Finally, qualification efforts should ideally target tool chains rather than individual tools.