[Interchange] XC7 OBUFDS misses a PIP begin enabled

[mkurc-ant]

In f4pga/prjxray#1705 for the OBUFDS test the Nextpnr flow completes. But when a DCP file is open in Vivado it shows a missing route for the net that connects both parts of the OBUFDS cell. There is a PIP (a pseudo one) that connects them. See the screenshot:

[mkurc-ant]

I have a suspicion what is happening: The device database defines macro expansion for:

• OBUFTDS -> OBUFTDS_DUAL_BUF
• OBUFDS -> OBUFDS_DUAL_BUF

But the latter is not defined in the macro library therefore nextpnr is not finding it. I've examined the output physical netlist and the OBUFTDS cell is not split there indeed. So this looks more like a RapidWright issue then.

[gatecat]

have you tried with Xilinx/RapidWright#203 ?

[mkurc-ant]

Yes I have (its merged). I double checked. The exceptionMap is there and contains correct entries for both OBUFTDS and OBUFDS.

But then there is the macro library which defines only one of the expanded macros (this comes from a device file converted to JSON):

{
  "name": "OBUFTDS_DUAL_BUF",
  "propMap": {
    "entries": []
  },
  "view": "netlist",
  "lib": "macros",
  "ports": [
    {
      "_id": 2633
    },
    {
      "_id": 2634
    },
    {
      "_id": 2635
    },
    {
      "_id": 2636
    }
  ],
  "_id": 3027
}

and there is no such entry for OBUFDS_DUAL_BUF

[gatecat]

Yeah, it really does look like it's missing from RapidWright (whereas it does exist in Vivado). The data file hdi_primitives.edf.test which appears to contain all the other macro expansions is missing it too.

[mkurc-ant]

This is now fixed by using a patched version of RapidWright and will be fixed in its next release. Closing.