Evaluating processor-behavior and three error-detection mechanisms using physical fault-injection

An approach for assessing the impact of physical injection of transient faults on processor execution is described and evaluated. The fault injection is based on two complementary methods using: (1) heavy-ion radiation; and (2) power supply disturbances. 12000 transient faults were injected into the target microprocessor, a Motorola MC6809E 8-bit CPU, running 3 different workloads. In the evaluation, the control-flow errors were distinguished from those that had no effect on the correct flow of control. The errors that led to wrong results are separated from those that did not affect the correct results. The errors that affected neither the correct control flow nor the correct results are specified. Effects of errors on the registers and signals of the processor are characterized, Workload dependency on error rates is demonstrated. Three error-detection mechanisms, (2 software-based mechanisms and 1 watchdog timer) were combined and used to characterize the detected and undetected errors. More than 87% of all errors and 93% of the control-flow errors could be detected. In a different test, the efficiency of an isolated watchdog timer was evaluated. The coverage of the isolated watchdog timer was only 62%. The results indicate that fault-injection methods, workloads, and programming languages all differently affect the control flow, coverage, latency, and error rates