The first step is to make sure that the IOB18 prjxray fuzzers are in place. We recommend you write a minitest via Vivado that exercises the IOB18 tile in your desired configuration, and ensure there are no unknown bits. Please open a PR on https://github.com/SymbiFlow/prjxray/ with your minitest so it can be added to the tests.

The first step is to make sure that the IOB18 prjxray fuzzers are in place. We recommend you write a minitest via Vivado that exercises the IOB18 tile in your desired configuration, and ensure there are no unknown bits. Please open a PR on https://github.com/SymbiFlow/prjxray/ with your minitest so it can be added to the tests.

It seems beyond my ability.Currently,I only try to generate the tile's bit that I want to get by modifying your code. And before add it to symbiflow,I have sucessfully in generating the design.json in minitest's roi_harness with the IOB18'db.

GitHub

SymbiFlow/prjxray

Documenting the Xilinx 7-series bit-stream format. - SymbiFlow/prjxray