PROToFLEX: FPGA-accelerated Hybrid Functional Simulator

Eric S. Chung, Eriko Nurvitadhi, James C. Hoe, Babak Falsafi, Ken Mai

Abstract: PROTOFLEX is an FPGA-accelerated hybrid simulation/emulation platform designed to support large-scale multiprocessor hardware and software research. Unlike prior attempts at FPGA multiprocessor system emulators, PROTOFLEx emulates full-system fidelityi.e., runs stock commercial operating systems with I/O support. This is accomplished without undue effort by leveraging a hybrid emulation technique called transplanting. Our transplant technology uses FPGAs to accelerate only common-case behaviors while relegating infrequent, complex behaviors (e.g., I/O devices) to software simulation. By working in concert with existing full-system simulators, transplanting avoids the costly and unnecessary construction of the entire target system in FPGA. We report preliminary findings from a working hybrid PROTOFLEx emulator of an UltraSPARC workstation running Solaris 8. We have also started developing a novel multiprocessor emulation approach that interleaves the execution of many (10s to 100s) processor contexts onto a shared emulation engine. This approach decouples the scale and complexity of the FPGA hostfrom the simulated system size but neverthe-less enables us to scale the desired emulation performance by the number of emulation engines used. Together, the transplant and interleaving techniques will enable us to develop full-system FPGA emulators of up to thousands of processors without an overwhelming development effort.