Early Experimental Verification of Fault Tolerance: the VHDL-based Fault Injection Tool MEFISTO-L

Abstract: Early verification of the adequacy of fault tolerance mechanisms, and the subsequent removal of fault tolerance deficiency faults (ftd-faults), are essential tasks in the design process of dependable computer systems. The paper is centred on the description and application of the new features of MEFISTO-L, the fault injection tool for VHDL models, being developed at LAAS for supporting the strategy that we have proposed for testing fault tolerance mechanisms. The paper first describes the overall testing framework in which MEFISTO-L is incorporated. Then, the testing strategy, and in particular the test outcome issue, is depicted. The tool is described in terms of its objectives, attributes, implementation and use; special attention is given to the main original and innovative features: i) the embedded VHDL code analyser facilitating the identification of the signals to be injected at different levels of the model hierarchy, ii) the observation and injection mechanisms, iii) their synchronisation, and iv) their automatic placement in the target VHDL model. Finally, an example of application of MEFISTO-L for specifying a fault injection campaign is presented.