QEMU stands for Quick Emulator. It is a generic and open source machine emulator. Xilinx provides a customized QEMU model that mimics the Arm based processing system present on Versal ACAP, Zynq® UltraScale+™ MPSoC, and Zynq-7000 SoC devices. The QEMU model provides the ability to execute CPU instructions at almost real time without the need for real hardware. For more information, refer to the Xilinx Quick Emulator User Guide: QEMU .
For hardware emulation, the Vitis emulation targets use QEMU and co-simulate it with an RTL and SystemC-based model for rest of the design to provide a complete execution model of the entire platform. You can boot an embedded Linux kernel on it and run the XRT-based accelerator application. Because QEMU can execute the Arm instructions, you can take the Arm binaries and run them in emulation flows as-is without the need to recompile. QEMU also allows you to debug your application using GDB and TCF-based target connections from Xilinx System Debugger (XSDB).
The Vitis emulation flow also uses QEMU to emulate the MicroBlaze™ processor to model the platform management modules (PLM and PMU) of the devices. On Versal devices, the PLM firmware is used to load the PDI to program sections of the PS and AI Engine model.
To ensure that the QEMU configuration matches the platform, there are additional files that must be provided as part of sw directory of Vitis platforms. Two common files, qemu_args.txt and pmc_args.txt, contain the command line arguments to be used when launching QEMU. When you create a custom platform, these two files are automatically added to your platform with default contents. You can review the files and edit as needed to model your custom platform. Refer to a Xilinx embedded platform for an example.
Because QEMU is a generic model, it uses a Linux device tree style DTB formatted file to enable and configure various hardware modules. A default QEMU hardware DTB file is shipped with the Vitis tools in the <vitis_installation>/data/emulation/dtbs folder. However, if your platform requires a different QEMU DTB, you can package it as part of your platform.