The Microarchitecture of FPGA-Based Soft Processors

Abstract

As more embedded systems are built using FPGA platforms, there is an increasing need to support processors in FPGAs. One option is the soft processor, a processor implemented in the reconfigurable logic of the FPGA. Commercial soft processors have been widely deployed, and hence we are motivated to understand their microarchitecture. We must re-evaluate microarchitecture in the soft processor context because an FPGA platform is significantly different than an ASIC platform. This dissertation presents an infrastructure for rapidly generating RTL models of soft processors, as well as a methodology for measuring their area, performance, and power. Using the automatically-generated soft processors we explore many interesting microarchitectural axes in the trade-off space. We also compare our designs to Altera's Nios II commercial soft processors and find that our automatically generated designs span the design space while remaining very competitive