A comparison of software-based techniques intended to increase the reliability of embedded applications in the presence of EMI

Corruption of the instruction pointer in an embedded computer system has been shown to be a common failure mode in the presence of electromagnetic interference, and previous investigators have suggested that the use of techniques such as ‘Function Tokens’ (FT) and ‘NOP Fills’ (NF) can reduce the impact of such failures. In this paper, both a statistical analysis and empirical tests of code from an embedded application are used to assess and compare these techniques. Two main results are presented. First, it is demonstrated that claims about the effectiveness of FT may neither be well founded nor generally applicable; specifically, it is concluded that rather than increasing system reliability, the use of FT will have the opposite effect. Second, it is demonstrated that NF may be easily applied in most embedded applications, and that the use of this approach can have a positive impact on system reliability.