Assured reconfiguration of fail-stop systems

Hardware dependability improvements have led to a situation in which it is sometimes unnecessary to employ extensive hardware replication to mask hardware faults. Expanding upon our previous work on assured reconfiguration for single processes and building upon the fail-stop model of processor behavior, we define a framework that provides assured reconfiguration for concurrent software. This framework can provide high dependability with lower space, power, and weight requirements than systems that replicate hardware to mask all anticipated faults. We base our assurance argument on a proof structure that extends the proofs for the single-application case and includes the fail-stop model of processor behavior. To assess the feasibility of instantiating our framework, we have implemented a hypothetical avionics system that is representative of what might be found on an unmanned aerial vehicle.