Generating Test Vectors for Vitis HLS during Hardware Emulation - 2025.2 English - UG1701

It is possible to instruct the Vitis tool to generate test vectors for simulation during hardware emulation, without re-running v++ compilation and linking. The test vectors will enable Vitis HLS to run C/RTL Co-simulation without a dedicated C++ test bench for:

• Deadlock analysis
• FIFO depth optimization
• Other performance optimizations

Use the following steps:

1. Create an hlsPre.tcl file and insert this command:

   config_export -cosim_trace_generation

2. Run v++ --compile and keep the HLS project directories, under the <compile_dir>
3. Run v++ --link --target hw_emu
4. Run the application for hardware emulation
5. Locate the hls_cosim inside the HW_EMU run directory
   1. This directory contains one directory for each kernel, with one directory for each kernel instance below it:

      <build_dir>/.run/<run_number>/hw_em/device0/binary_0/behav_waveform/xsim/hls_cosim/<kernel_name>

6. Copy the appropriate kernel directory to the HLS project directory, i.e.:

   cp -r <build_dir>/.run/<run_number>/.../xsim/hls_cosim/<kernel_name> <compile_dir>/<kernel_name>/<kernel_name>

7. Open the Vitis HLS tool and run C/RTL Co-simulation in batch mode or GUI mode:

   cosim_design -hwemu_trace_dir <kernel_name>/<instance_name> ...

The traces generated from HW_EMU are valid only as long as:

• The functionality of the kernel does not change
• The top interface of the kernel does not change
• The number of top interface reads and writes (s_axilite registers, m_axi interfaces, axis interfaces) does not change.