Open source FPGA toolchains

[ozel]

great project!
I wonder if you have tried one of the open source toolchains for FPGA synthesis, for example openXC7 which is based on yosys/nextpnr, as an alternative to Vivado?
If there where issues, I would be curious about those, too.

[elipsitz]

Hey, good question. When I first looked into it ~4 years ago, the open source toolchains were lacking some pretty critical features for Xilinx Series 7 chips. I'm sure they've made substantial progress since then, but I haven't given it another try.

If they're up to the task now, you'd definitely still need to make some changes, since Game Bub uses Xilinx Parametrized Macros (XPM) for some clock domain crossing. And those are shipped as part of Vivado.