Abstract
The continuous scaling of semiconductor technologies has significantly increased the susceptibility of modern processors to transient faults, particularly soft errors induced by radiation effects such as single-event upsets and multiple-bit upsets. This challenge is especially critical in safety-critical embedded systems deployed in automotive, aerospace, industrial control, and high-reliability computing environments, where incorrect computation can lead to catastrophic consequences. Lockstep-based redundancy, dual-core and triple-core architectures, dynamic and heterogeneous replication techniques, and reconfigurable fault recovery mechanisms have therefore emerged as fundamental design strategies to ensure dependable operation. This article presents an extensive and original research-oriented analysis of lockstep and redundant multicore processor architectures for soft error mitigation, grounded strictly in the provided body of literature. Drawing from experimental heavy-ion irradiation studies, industrial processor implementations, FPGA-based softcore designs, and architectural modeling of fault trends, the paper elaborates on the theoretical foundations of fault tolerance, the evolution of lockstep techniques, and the practical design trade-offs between performance, area, power, and reliability. Methodological aspects are explored in detail, including architectural replication, error detection and comparison mechanisms, context reloading, dynamic lockstep activation, heterogeneous core approaches, and system-level monitoring using trace and debug infrastructures. The results are discussed in a descriptive and interpretive manner, emphasizing resilience improvements, detection coverage, and recovery behavior under realistic fault conditions. The discussion further addresses limitations, scalability concerns, and future research directions, particularly in the context of emerging automotive zonal controllers and highly integrated system-on-chip platforms. By synthesizing theoretical insights with practical design evidence, this article aims to serve as a comprehensive academic reference on lockstep and redundant multicore fault-tolerant processor architectures.