Hard Processor System Booting User Guide: Agilex™ 3 and Agilex™ 5 SoCs

ID 813762
Date 5/09/2025
Public
Document Table of Contents

3.2.3. Single SDM Flash

In a single flash attached to SDM layout, the flash contains all of the files required for booting, including the configuration bitstream and the OS files.

Depending on the boot stage that performs the FPGA configuration, you have the following options for storing the FPGA core and I/O configuration file:
  • An SDM flash storage partition—In this case, the SSBL initiates configuration.
  • In the OS file system—In this case the OS initiates configuration.

The QSPI controller is shared between the SDM and the HPS and only one of these can access the QSPI device at a time. At power-up, the SDM receives access to the QSPI controller. If the HPS needs access to the QSPI flash device, the software running in this (for example, the FSBL or SSBL) must request ownership from the SDM through the HPS-to-SDM mailbox. After the HPS gains ownership of the QSPI controller, it retains ownership until any of the following events occur:

  • A power cycle
  • A HPS reset
  • An HPS reboot generated for an RSU event
For more information, refer to:
  • Device and Pin Options for device configuration that allow the HPS to be granted with the QSPI ownership.
  • QSPI Controller Ownership Selection Impact on the HPS software for more information about how the QSPI ownership affect the HPS software.
  • Appendix A.2. HPS Use of SDM QSPI Controller in the Hard Processor System Technical Reference Manual: Agilex™ 5 SoCs.
  • Appendix A.2. HPS Use of SDM QSPI Controller in the Hard Processor System Technical Reference Manual: Agilex™ 3 SoCs.

In the Quad SPI flash example, the SSBL, OS and file system reside in the Unsorted Block Image File System (UBIFS).

Figure 9. HPS Boot First Layout with Quad SPI