MetaKernels and fault containment wrappers

This paper addresses the problem of using COTS microkernels in dependable systems. Because they are not developed with this aim, their behavior in the presence of faults is a main concern to system designers. We propose a novel approach to contain the effect of both external and internal faults that may affect their behavior. As microkernels can be decomposed into simple components, modeling of their expected behavior in the absence of faults is most often possible, which allows for the easy definition of dynamic predicates. For an efficient implementation of fault containment wrappers checking for these predicates, we introduce the notion of MetaKernel to reify the information required for implementing the predicates and to reflect appropriate actions. This approach is exemplified on a case study using an open version of the Chorus microkernel. MAFALDA, a software-implemented fault injection tool, is used to illustrate the benefits procured by the proposed wrappers.