McQEMU: Time-Accurate Simulation of Multi-core platforms using QEMU

Abstract

Full-system emulators allow the execution of guest operating systems and applications without the need of having access to the real target hardware. For many applications, besides the correct functional modeling, the full-system emulator shall also be time-accurate. In this paper, we present a new full-system multi-core simulator that delivers time-accurate execution and preserves the functional correctness of guest application. The proposed solution is based on QEMU. We enriched QEMU with various time models of multi-core platforms. We call this new full-system simulator mcQEMU. mcQEMU supports guest CPUs with out-of-order and in-order architectures.We validated mcQEMU by emulating multi-core ARM processors in system mode. The time accuracy of mcQEMU is evaluated with the TACLeBench benchmark suite. From a timing prediction viewpoint, mcQEMU achieves an estimation error of only 15% in average when emulating the out-of-order i.MX6Quad processor by NXP. For full-system simulation, mcQEMU runs at 35 Mips for in-order architectures and 25 Mips for out-of-order ones. In user-mode simulation, mcQEMU can achieve up to 65 Mips.