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chipsalliance / fpga-interchange-tests

Repository to run extensive tests on the FPGA interchange format
https://chipsalliance.github.io/fpga-interchange-tests
ISC License
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Need to specify all cell's IOs for correct DCP #40

Open acomodi opened 3 years ago

acomodi commented 3 years ago

When explicitly instantiating a cell, all the IOs need to be explicitly stated, or otherwise an invalid DCP is generated, where the cell results to be unplaced, despite being present in the physical netlist.

I will provide a small and reproducible test case soon to showcase the issue.

gatecat commented 3 years ago

If we specify the default cell connections then this should be avoidable, as nextpnr should create and connect these ports automatically.

RapidWright isn't currently generating these and I don't think it has data for those, but perhaps this is something that could be added (I demonstrated how Vivado handles this at https://github.com/SymbiFlow/fpga-interchange-schema/pull/35#issuecomment-819709256 )

acomodi commented 3 years ago

Ok, thanks for the pointers.

In case RW cannot get the required data, I wonder whether it might be a valid (and feasible) solution to patch the device? It may be quite verbose to add a patch for all the cells, but I cannot think of another way of providing this data.