Debugging of hardware blocks on an FPGA is always challenging and may be frustrating, especially with no reliable tools at hands. Way too often the process turns into developing and debugging of the tools, instead of a target design.
Commercial solutions are available (SignalTap, ChipScope, Synopsys Identify RTL Debugger, MicroSemi Smart Debug), at the same time there are a lot of well known problems associated with them: vendor lock, single target, closed source and not always flexible enough, license terms and costs.
Owing to free software developers essential tools for on-hardware debugging of IP cores are available today. However there are problems associated with these tools too. Among the most notable ones are a weak integration between separate tools and small bits of code and config files missing here and there. A working combination of tools along with explanations of how they may be used together to debug IP cores is provided. A presentation covers such free software as GHDL, sigrok/PulseView, and OpenOCD. Source code of free IP cores, all configuration and script files and presentation slides will be available in a dedicated repository on github.
A live demonstration of the PulseView connected to an in-FPGA logic analyzer via JTAG interface and working in parallel with a gdb debug session on a RISC-V soft-core CPU in the same FPGA with an open and low-cost hardware will be presented.
An outline of the open tasks and possible future development directions concludes the presentation.