Iterative or Incremental AI Engine Application Compilation - 2024.1 English

AI Engine application development can start early in the system development stage. Gradually, the AI Engine development team and the hardware development team converge on an interface between the Programmable Logic and the AI Engine array. At some point, this interface is fixed and should not be changed, but the AI Engine logic can continue to evolve as long as this interface remains unchanged. Essentially the logic inside the AI Engine application can change as long as the interface to the PL kernels and the platform does not.

The hardware and the AI Engine development teams can have independent development processes. After an AI Engine application compilation, the compiler generates many files in the Workdirectory that identify the decisions made during the entire process. One of the files called Work/temp/graph_aie_routed.aiecst contains, among other information, all the interface specification between the AI Engine array, and the PL and PS in JSON format. The NodeConstraints area contains the description of all the interfaces you defined in your graph, with their column location and channel selection.

1. You can extract this data and store it in another file in JSON format:

   {
    "NodeConstraints": {
      "DataIn1": {
        "shim": {
          "column": 24, 
          "channel": 0 
          } 
        },
      "clip_in": { 
        "shim": { 
          "column": 24, 
          "channel": 0 
          } 
        }, 
      "clip_out": { 
        "shim": { 
          "column": 25, 
          "channel": 0 
        } 
      }, 
      "DataOut1": { 
        "shim": { 
          "column": 25, 
          "channel": 0 
        } 
      } 
    } 
   }

2. The AI Engine application can be modified and recompiled by providing the previously extracted interface constraints file to the compiler:

   v++ -c --mode aie $(AIE_FLAGS) --workdir=./Work2 --constraints=interface.aiecst graph.cpp
   

A new libadf.a is created, unless you specify another name, and can be directly packaged with the XSA that has been generated previously by the link stage and the host executable.

You can manually change the constraints file without having to wait for a new link of the system and provide your libadf.a file afterwards to the hardware team.

A tutorial including all the steps to perform this task is available at: https://github.com/Xilinx/Vitis-Tutorials/tree/2023.1/AI_Engine_Development/Feature_Tutorials/15-post-link-recompile.

Developing the AI Engine Software using a Fixed Hardware Platform

v++ -c --mode aie -include ... -platform=LinkedPlatform.xsa  newgraph.cpp

The host code can also be adapted to the new graph, compiled and packaged with the new libadf.a to generate an image.