After you have configured your hardware project, the PetaLinux project requires a hardware description file (.xsa file) with information about the processing system. You can get the hardware description file by running Export Hardware from the Vivado® Design Suite.
During project initialization (or update), PetaLinux generates a device tree source file, U-Boot configuration header files (MicroBlaze processors only), and enables the Linux kernel drivers (MicroBlaze processors only) based on the hardware description file. These details are discussed in PetaLinux Project Structure.
For Zynq® UltraScale+™ MPSoC platform, you need to boot with the Platform Management Unit (PMU) firmware and Arm Trusted Firmware(TF-A). See Generating Boot Components for building PMU firmware and TF-A. If you want a first stage boot loader (FSBL) built for Cortex®-R5F boot, you have to build it with the Vitis™ software platform because the FSBL built with PetaLinux tools is for Cortex-A53 boot. For details on how to build the FSBL for Cortex-R5F with the Vitis software platform, see the Zynq UltraScale+ MPSoC: Software Developers Guide (UG1137).
For Versal platforms, boot with Platform Loader and Management Firmware(PLM), Platform System Management Firmware(PSM) and TF-A. See Generating Boot Components for building the PLM, PSM, and TF-A.