Hard Processor System Booting User Guide: Agilex™ 5 SoCs

ID 813762
Date 4/01/2024
Public
Document Table of Contents

3.1.4. Second-Stage Bootloader

The second-stage bootloader (SSBL) is the second boot stage for the HPS. The FSBL initiates the copy of the SSBL to the HPS SDRAM. The SSBL typically enables more advanced peripherals such as Ethernet and supports the command line interface.

You can create the HPS SSBL from one of the following sources:

  • U-Boot
    • Intel provides the source code for U-Boot on GitHub.
  • Arm* Trusted Firmware
    • Intel provides the source code for the Arm* Trusted Firmware on GitHub.

You can optionally perform FPGA core and I/O configuration in during the SSBL stage. The SSBL copies the FPGA configuration files from one of the following sources to the HPS SDRAM:

  • HPS Flash
  • SDM Flash
  • External host via the HPS Ethernet (for example, TFTP)

After the SSBL copies the FPGA configuration files to the HPS SDRAM, the SSBL can initiate a configuration request to the SDM to begin the configuration process.

For ATF Linux Boot and ATF Zephyr* Boot, the FPGA configuration happens in the Operating System stage.