3. Compile the A72 Host Application - 2022.2 English

After all the new AI Engine outputs are created, you can compile your host application by following the typical cross-compilation flow for the Cortex-A72. As you might notice, the host code uses XRT (Xilinx Run Time) as an API to talk to the AI Engine and PL kernels. Notice that in the linker, it is using the libraries: -ladf_api_xrt -lxrt_coreutil.

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

   Note: XRT is used in the host application. This API layer is used to communicate with the programmable logic, specifically the PLIO kernels for reading and writing data. To understand how to use this API in an AI Engine application refer to “Programming the PS Host Application”.

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

   • GCC_FLAGS: Self-explanatory that you will be compiling this code with C++ 14. More explanation will be provided in the packaging step.

   • GCC_INCLUDES: Contains the list of all the necessary include files from the SDKTARGETSYSROOT as well as the AI Engine tools.

3. Close the Makefile, and run the command:

   make host
   

   Or

   cd ./sw
   aarch64-xilinx-linux-g++ -Wall -c -std=c++14 -D__SYNCBO_ENABLE__ -D__PS_ENABLE_AIE__ -Wno-int-to-pointer-cast --sysroot=$SDKTARGETSYSROOT -	   I$SDKTARGETSYSROOT/usr/include/xrt -I$SDKTARGETSYSROOT/usr/include -I./ -I../aie -I$XILINX_VITIS/aietools/include -I$XILINX_VITIS/include -o aie_control_xrt.o ../Work/ps/c_rts/aie_control_xrt.cpp
   
   aarch64-xilinx-linux-g++ -Wall -c -std=c++14 -D__SYNCBO_ENABLE__ -D__PS_ENABLE_AIE__ -Wno-int-to-pointer-cast --sysroot=$SDKTARGETSYSROOT -I$SDKTARGETSYSROOT/usr/include/xrt -I$SDKTARGETSYSROOT/usr/include -I./ -I../aie -I$XILINX_VITIS/aietools/include -I$XILINX_VITIS/include -o host.o host.cpp
   
   aarch64-xilinx-linux-g++ host.o aie_control_xrt.o -ladf_api_xrt -lxrt_coreutil -L$SDKTARGETSYSROOT/usr/lib --sysroot=$SDKTARGETSYSROOT -L$XILINX_VITIS/aietools/lib/aarch64.o -o host.exe
   
   cd ..
   

The follow table describes some of the GCC options being used:

Flag	Description
-Wall	Print out all warnings.
-Wno-int-to-pointer-cast	Warn about an integer to pointer cast.
--sysroot	Tells the compiler where to find the headers/libs for cross-compile.
-std=c++14	This is required for Linux applications using XRT.