Step 4 - Compiling Host Code - 2023.2 English

When the v++ linker is complete, you can compile the host code that will run on the Linux that comes with the platform. Compiling code for the design requires the location of the SDKTARGETSYSROOT or representation of the root file system, that can be used to cross-compile the host code.

1. Open ./sw/host.cpp, and familiarize yourself with the contents. Pay close attention to API calls and the comments provided.

   Do take note that Xilinx Runtime (XRT) is used in the host application. This API layer is used to communicate with the PL, specifically the PLIO kernels for reading and writing data. To understand how to use this API in an AI Engine application, see Programming the PS Host Application.

   The output size of the kernel run is half of what was allocated earlier. This is something to keep in mind. By changing the s2mm kernel from a 32-bit input/output to a 64-bit input/output, the kernel call will be adjusted. If this is not changed, it will hang because XRT is waiting for the full length to be processed when in reality half the count was done (even though all the data will be present). In the host.cpp, look at line 117 and 118 and comment them out. You should have uncommented the following line:

   xrtRunHandle s2mm_rhdl = xrtKernelRun(s2mm_khdl, out_bohdl, nullptr, sizeOut/2);
   

2. Open the Makefile, and familiarize yourself with the contents. Take note of the GCC_FLAGS and GCC_LIB.

   • GCC_FLAGS: Should be self-explanatory that you will be compiling this code with C++.

   • GCC_LIB: Has the list of all the specific libraries you will be compiling and linking with. This is the minimum list of libraries needed to compile an AI Engine application for Linux.

3. Close the makefile and run the command: make host.

With the host application fully compiled, you can now move to packaging the entire system.