Hardware Emulation - 2020.2 English

Vitis Unified Software Platform Documentation: Application Acceleration Development (UG1393)

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2020.2 English

Hardware emulation runs an RTL simulation of the programmable logic design, where the PL kernels are integrated with a cycle-approximate model of the hardware platform.

Hardware emulation is especially useful for the following tasks:

  • Checking the functional correctness of the RTL code synthesized from the C, C++, or OpenCL kernel code
  • Testing the interactions between different kernels or multiple CUs
  • Using hardware waveforms to gain detailed visibility into internal activity of the kernels
  • Getting initial performance estimates for the application

Each kernel is compiled to a hardware model (RTL). During hardware emulation, kernels are run in the Vivado logic simulator, with a waveform viewer to examine the kernel design. Some third-party simulators are also supported as described in RTL Simulator Support. In addition, hardware emulation provides performance and resource estimates for the hardware implementation.

SystemC models are provided for the key IP used in the hardware platform, like Versal NoC/DDR memory, CIPS, PS block, AI Engine, UltraScale+ MIG DDR memory, and AXI4 SmartConnect. These IP models are used during hardware emulation to improve simulation performance and results.

In hardware emulation, compile and execution times are longer than software emulation, but it provides a detailed, cycle-accurate, view of kernel activity. Xilinx recommends using small data sets for validation during hardware emulation to keep runtimes manageable.

Important: The DDR memory model and the memory interface generator (MIG) model used in hardware emulation are high-level simulation models. These models provide good simulation performance, but only approximate latency values and are not cycle-accurate like the kernels. Therefore, performance numbers shown in the profile summary report are approximate, and should be used for guidance and for comparing relative performance between different kernel implementations.

As discussed in Vitis Compiler Command, the hardware emulation target is specified in the v++ command with the -t option:

v++ -t hw_emu ...