NetCracker: A Peek into the Routing Architecture of Xilinx 7-Series FPGAs

Abstract

Novel applications have triggered significant changes at the system level of FPGA architecture design, such as the introduction of embedded VLIW processor arrays and hardened NoCs. However, the routing architecture of the soft logic fabric has largely remained unchanged in recent years. Since hunger for acceleration of ever more varied tasks with various power budgets---as well as complications related to technology scaling---is likely to remain significant, it is foreseeable that the routing architecture too will have to evolve. In this work, we do not try to suggest how routing architectures of tomorrow should look like. Instead, we analyze an existing architecture from a popular commercial FPGA family, discussing the possible origins of various design decisions and pointing out aspects that may merit future research. Moreover, we present an open-source tool that greatly eases such analyses, relying only on data readily available from the vendor CAD tools. Our hope is that this work will help the academic research community in catching up with the current developments in industry and accelerate its contributions to FPGA architectures of the future.