TCCF: Tightly-Coupled Co-simulation Framework for RISC-V Based Systems

The development of heterogeneous systems where a CPU has to interact with a custom HDL design is particularly critical; these systems must, in fact, rely on the cooperation of sub-systems developed by (usually) separate teams and tested in isolation, typically by developing a mock system to represent the counterpart and running made-up test benches for some limited scenarios. This approach often postpones the discovery of issues to the system integration stage, where locating them is more complex and fixing them more expensive. In this paper we present TCCF, a QEMU/ModelSim-based framework that allows the complete co-simulation of heterogeneous systems. Having full visibility on the internals during HW/SW interactions enables to quickly spot incongruences and mistakes in the interface design, as well as to perform in-depth investigations on system’s failures and behavior. We have validated TCCF on a variety of publicly-available IP cores and platforms. The framework is easily extensible to cover custom protocols and operating systems, and is available under a GPL-3.0 license.