Static/dynamic real-time legacy software migration: a comparative analysis

Evolution to next generation embedded systems is shortening the obsolescence period of the underlying hardware. As this happens, software designed for those platforms (a.k.a., legacy code), that might be functionally correct and validated code, may be lost in the architecture and peripheral change. As embedded systems often have Real-Time (RT) computing constraints, the legacy code retargeting issue directly affects RT systems. Binary translation techniques have been widely applied for legacy code migration. However, there are just a few works that consider RT legacy code. Therefore, this paper presents a static and a dynamic binary migration approach (based on QEMU and Rev.ng respectively) and analyzes and compares their suitability as RT code migration solutions. The comparison shows that among the proposed solutions, the static is the most appropriate for short-running RT legacy code, since it ensures lower translation overhead and a more deterministic timing behavior. Instead, the dynamic approach might be a suitable solution for RT legacy code with long periods (over 0.01 s) and mainly composed of complex floating point computations, since the dynamic translation and optimization overhead is not that significant on long-running benchmarks and the static translation implies a great slowdown on benchmarks containing floating point operations.