Processor rescue safe coding for hardware aliasing

Abstract

What happens if a Mars lander takes a cosmic ray through the processor and thereafter 1 + 1 = 3? Coping with the fault is feasible but requires the numbers 2 and 3 to be treated as indistinguishable for the purposes of arithmetic, while as memory addresses they continue to access different memory cells. If a program is to run correctly in this altered environment it must be prepared to see address 2 sporadically access data in memory cell 3, which is known as ‘hardware aliasing’. This paper describes a programming discipline that allows software to run correctly in a hardware aliasing context, provided the aliasing is underpinned by hidden determinism.