AN 709: HPS SoC Boot Guide - Cyclone V SoC Development Kit

ID 683265
Date 1/27/2016
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1.2.2.1. Boot from SD/MMC

When booting from SD/MMC, two different options are available:

  • Raw mode - Preloader images are located at address0 on the card.
  • Partition mode - Preloader images are located at offset 0 on a custom partition with ID=A2 on the card.
Figure 3. Raw Mode and Partition Mode Options

The MBR is a 512 byte data structure, located at address 0, describing the partitions existing on the SD/MMC card.

The Raw mode does not allow the card to be partitioned, since the Preloaders are located at address 0, where the MBR data structure needs to be placed.

When using the Partition mode, the Preloader is located on a custom partition that does not interfere with the other partitions on the SD/MMC card. The other partitions could, for example, contain Windows FAT, or Linux EXT2 or EXT3 file systems, providing more flexibility for the overall system design.