This document provides a comprehensive overview of the partitions of all boot devices on SP7350 platform. The SP7350 platform supports 5 boot devices, including SPI-NOR flash, SPI-NAND flash, 8-bit NAND flash, eMMC device, and SD card.
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Partition | Size | Descriptions |
|---|---|---|
nand_header | 1 block | header of the NAND flash |
xboot1 | Actual size of image | image of x-boot, including training firmware of DDR |
uboot1 | Actual size of image | image of U-Boot (factory default) |
uboot2 | Actual size of image | image of U-Boot (the latest update) |
fip | 2 MB | image of fip, including TF-A and OP-TEE |
env | 512 kB | image of environment variable of U-Boot |
env_redund | 512 kB | image of environment variable of U-Boot (redundant) |
dtb | 256 kB | image of device-tree blob (not used) |
kernel | 25 MB | image of Linux kernel with U-Boot header |
rootfs | Depend on size of flash | image of ubifs root file-system |
It is essential to ensure that the combined size of the nand_header, xboot1, uboot1, and uboot2 partitions does not exceed 4 MB. This constraint is crucial as the fip partition initiates at a 4 MB offset.
If a 128MB, 512MB, or any other size NAND flash is utilized, the size of the rootfs partition will dynamically adjust to either shrink or extend to occupy the space available on the NAND flash up to its full capacity. However, the sizes of other partitions will remain unchanged.
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If a 2GB, 4GB, or any other size eMMC is utilized, the size of the rootfs partition will dynamically adjust to either shrink or extend to occupy the space available on the eMMC up to its full capacity. However, the sizes of other partitions will remain unchanged.
Overlay File System
If overlay file-system is chosen, an additional partition called overlay is added after rootfs partition. Refer to the figure below where overlay partition is added:
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Please refer to the table below for an explanation of rootfs and overlay partitions:
Partition | Size | Descriptions |
|---|---|---|
rootfs | Actual size of rootfs | The lower directory of the overlay file-system. This is a read-only file system containing the base root file-system, in squashfs format. |
overlay | Depend on size of device | The upper directory of the overlay file-system. This is the writable file system where any changes are stored, in ext4 format. |
SD Card
The SP7350 platform offers support for booting from an SD card, providing a convenient solution for updating system images, particularly during the developmental stage or debugging. Although the SD card may exhibit lower performance compared to the eMMC device, its utility in certain scenarios remains valuable.
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