10. SD Card Boot Utility
The Preloader is typically stored in a custom partition (with type = 0xA2) on the SD card. Optionally, the next boot stage (usually the Bootloader) can also be stored on the same custom partition.
Since it is a custom partition without a file-system, the Preloader, Bootloader, or both cannot be updated by copying the new file to the card; and a software tool is needed.
The SD card boot utility allows you to update the Preloader, Bootloader, or both on a physical SD card or a disk image file. The utility is not intended to create a new bootable SD card or disk image file from scratch. In order to do that, it is recommended to use fdisk on a Linux* host OS.