Using run-time reconfiguration for fault injection applications

The probability of faults occurring in the field increases with the evolution of the CMOS technologies. It becomes, therefore, increasingly important to analyze the potential consequences of such faults on the applications. Fault injection techniques have been used for years to validate the dependability level of circuits and systems, and approaches have been proposed to analyze very early in the design process the functional consequences of faults. These approaches are based on the high-level description of the circuit or system and classically use simulation. Recently, hardware emulation on FPGA-based systems has been proposed to accelerate the experiments; in that case, an important characteristic is the time to reconfigure the hardware, including re-synthesis, place and route, and bitstream downloading. In this paper, an alternative approach is proposed, based on hardware emulation and run-time reconfiguration. Fault injection is carried out by direct modifications in the bitstream, so that re-synthesizing the description can be avoided. Moreover, with some FPGA families (e.g., Virtex or AT6000), it is possible to reconfigure the hardware partially at run-time. Important time-savings can be achieved when taking advantage of these features, since the injection of a fault necessitates the reconfiguration of only a few resources of the device. The injection process is detailed for several types of faults and experimental results are discussed.