Fast simulation of future 128-bit architectures

Abstract

Whether 128-bit architectures will some day hit the market or not is an open question. There is however a trend towards that direction: virtual addresses grew from 34 to 48 bits in 1999 and then to 57 bits in 2019. The impact of a virtually infinite addressable space on software is hard to predict, but it will most likely be major. Simulation tools are therefore needed to support research and experimentation for tooling and software. In this paper, we present the implementation of the 128-bit extension of the RISC-V architecture in the QEMU functional simulator and report first performance evaluations. On our limited set of programs, simulation is slowed down by a factor of at worst 5 compared to 64-bit simulation, making the tool still usable for executing large software codes.