Demystifying Soft Error Assessment Strategies on ARM CPUs: Microarchitectural Fault Injection vs. Neutron Beam Experiments

Fault injection in early microarchitecture-level simulation CPU models and beam experiments on the final physical CPU chip are two established methodologies to access the soft error reliability of a microprocessor at different stages of its design flow. Beam experiments, on one hand, estimate the devices expected soft error rate in realistic physical conditions by exposing it to accelerated particles fluxes. Fault injection in microarchitectural models of the processor, on the other hand, provides deep insights on faults propagation through the entire system stack, including the operating system. Combining beam experiments and fault injection data can deliver deep insights about the devices expected reliability when deployed in the field. However, it is yet largely unclear if the fault injection error rates can be compared to those reported by beam experiments and how this comparison can lead to informed soft error protection decisions in early stages of the system design.