[rwmj]

At least some Xilinx 7-series FPGAs have been reverse engineered: https://yosyshq.readthedocs.io/projects/yosys/en/latest/cmd/...

[robinsonb5]

There's been some interesting recent work to get the QMTech Kintex7-325 board (among others) supported under yosys/nextpnr - https://github.com/openXC7 It works well enough now to build a RISC-V SoC capable of running Linux.