Mass Storage Partition Configuration

This section describes how to configure the mass storage partition.

The platform supports formatting mass storage media into multiple partitions for storing data, such as device OS images and boot loader images. Data inside these partitions are not end-user visible through the typical OS filesystems.

The platform also supports the GUID partition table GPT scheme for defining the layout of the partition table on a physical hard disk.

Creating Partitions

Options for creating partitions differ between boot media and non-boot-media.

  • For boot media (for QSPI media), the partition layout is passed from the kernel command line or via the DT node. The partition layout is a kernel interpretation. The boot loader continues to use the partition table (PT).
  • For non-boot-media (eMMC/SD card), you can create partitions from user-space or by using bootburn. However, if you update the partition from user-space, the partition layout for the boot loader will go out of sync with the partitions. This is because user-space uses GPT for storing partition layout. In contrast, Boot loader uses the PT definitions.

For best practices, expose non-system partitions to user-space, excluding the system partitions like BCT, PT, boot loaders, and kernel partitions. To update system partitions using update tools, it is recommended that whole flash be exposed to user-space in the kernel.

For information about the flashing flow, see Flashing with Bootburn.

Multipartition Architecture

The partition properties are:

  • Base address, expressed as bytes
  • Length, expressed as bytes
  • Name, maximum 20 character-length string
  • Storage device ID
  • File system type
  • Flag indicating whether the partition is to be write-protected on boot.