How do I use the BlockPlacer2 to place a design

[burntfalafel]

Hi! I have a verilog file which I want to place using RapidWright's framework (maybe if possible routing too).

My current flow is

1. download a dcp (or create one. For this e.g. we can use the RapidWright tutorial site one - using wget http://www.rapidwright.io/docs/_downloads/gnl_2_4_7_3.0_gnl_3500_03_7_80_80.dcp)
2. read the checkpoint file in RapidWright using Design.readCheckpoint
3. Use the BlockPlacer2Module followed by placeDesign() to place the design.
4. Write a new checkpoint file

This flow errors out for me at step 2 saying:

Exception in thread "main" java.lang.RuntimeException: no paths found
at com.xilinx.rapidwright.placer.blockplacer.BlockPlacer2Module.populateAllPaths(BlockPlacer2Module.java:294)
at com.xilinx.rapidwright.placer.blockplacer.BlockPlacer2.initializePlacer(BlockPlacer2.java:215)
at com.xilinx.rapidwright.placer.blockplacer.BlockPlacer2.placeDesign(BlockPlacer2.java:415)

Does anyone have a better flow in mind or can suggest corrections to the flow I am using? I have attached the code I am using below for reference.

Thanks :)

package com.xilinx.rapidwright.examples;

import java.nio.file.Path;
import java.nio.file.Paths;

import com.xilinx.rapidwright.design.Design;
import com.xilinx.rapidwright.design.blocks.PBlock;
import com.xilinx.rapidwright.placer.blockplacer.BlockPlacer;
import com.xilinx.rapidwright.placer.blockplacer.BlockPlacer2;
import com.xilinx.rapidwright.placer.blockplacer.BlockPlacer2Module;
import com.xilinx.rapidwright.util.FileTools;

public class testPlace {

    public static void main(String[] args) {
        // Check args
        if (args.length != 2) {
            System.out.println("USAGE: java " + testPlace.class.getCanonicalName() + " "
                            + "<synth_dcp_filename> <output_dcp>");
            return;
        }
      
        // Read checkpoint
        Design design = Design.readCheckpoint(args[0]);

        BlockPlacer2Module placer = new BlockPlacer2Module(design);
        placer.placeDesign(false);

        // Write out the results
        design.writeCheckpoint(args[1]);
    }
}

[clavin-xlnx]

Hi @burntfalafel, thanks for the question! It turns out that RapidWright currently doesn't have a built-in, fully automatic general placement tool. The BlockPlacer2 which you have mentioned is for placing a design composed of pre-implemented modules, which is more of a special case as it is a RapidWright-specific design construct.

One other option is DREAMPlaceFPGA which just added some preliminary support for UltraScale+ designs similar to the GNL design you cited. The process to use it is a bit more involved (need to convert the DCP to bookshelf format, use DREAMPlaceFPGA to place, export as an FPGA Interchange Format result, import back to RapidWright to create a DCP). Directions on how to use it with RapidWright and the FPGA Interchange Format are here:

https://github.com/rachelselinar/DREAMPlaceFPGA/tree/main/IFsupport

In theory, you could also route the design in RapidWright with our router, RWRoute. There was a recent issue that appears to have been fixed, so its possibly resolved now, I just haven't had a chance to test.