Hardware runtime monitoring for dependable cots-based real-time embedded systems

COTS peripherals are heavily used in the embed-ded market, but their unpredictability is a threat for high-criticality real-time systems: it is hard or impossi-ble to formally verify COTS components. Instead, we pro-pose to monitor the runtime behavior of COTS peripherals against their assumed specifications. If violations are de-tected, then an appropriate recovery measure can be taken. Our monitoring solution is decentralized: a monitoring de-vice is plugged in on a peripheral bus and monitors the peripheral behavior by examining read and write trans-actions on the bus. Provably correct (w.r.t. given speci-fications) hardware monitors are synthesized from high level specifications, and executed on FPGAs, result-ing in zero runtime overhead on the system CPU. The pro-posed technique, called BusMOP, has been implemented as an instance of a generic runtime verification frame-work, called MOP, which until now has only been used for software monitoring. We experimented with our tech-nique using a COTS data acquisition board. 1