Evaluating the fault tolerance capabilities of embedded systems via BDM

Fault injection is a viable solution for verifying the correct design and implementation of fault tolerance mechanisms at different levels (hardware and software). The paper discusses the use of the background diagnostic mode (BDM), available on several Motorola microprocessors and microcontrollers, for implementing a fault injection environment. BDM is well suited to implement some of the most critical operations required by a fault injection environment, such as activating the injection procedure, injecting the fault in memory or registers, and observing the faulty system behavior. The characteristics of a BDM-based fault injection environment in terms of intrusiveness, flexibility, time efficiency, and system requirements are analyzed. The authors exploit a prototypical environment they implemented to validate this analysis. As a result, the approach appears to be well suited for implementing low-cost fault injection experiments on simple embedded microprocessor- and microcontroller-based boards. Some limitations are also outlined, mostly in terms of execution time slow-down.