Partition-Based Faults Diagnosis of a VLIW Processor

International audienceReconfigurable systems are increasingly used in different domains, due to the advantages they offer in terms of flexibility: reconfigurability can also be used for managing possible faults affecting a circuit, when fault tolerance is the target. In this case the system must be able to (1) detect any possible fault, (2) identify the module (or partition) including it, and (3) take proper actions able to overcome the problem (e.g., by substituting the faulty module with a spare one). In this chapter, we address the point (2) when a Very Long Instruction Word (VLIW) processor is used by resorting to a Software-Based Self-Test (SBST) approach. SBST techniques have shown to represent an effective solution for permanent fault detection and diagnosis, both at the end of the production process, and during the operational phase. When VLIW processors are addressed, SBST techniques can effectively exploit the parallelism intrinsic in these architectures. In this chapter, we propose a new approach that starting from existing detection-oriented programs generates a diagnosis-oriented test program. Moreover, we propose (1) a detailed analysis of the generated equivalence classes and (2) a solution aimed to maximize the diagnosability of the modules composing the VLIW processor under test, thus perfectly suiting the needs of reconfigurable systems. Experimental results gathered on a case study VLIW processor show the effectiveness of the proposed approach: at the end of the presented method, the faulty module is always identified