Exploring partitions of all boot devices on SP7350 platforms

This document provides a comprehensive overview of the partitions of all boot devices on SP7350 platform.

SPI-NOR flash

SP7350 supports two kinds of root file-system for SPI-NOR flash. One is initramfs (initial ram file-system) file-system and the other is jffs2 (journalling flash file system version 2) file-system.

Initramfs File-System

The initramfs file-system is a RAM-based file system seamlessly integrated into the kernel image. Despite modifications to the root file-system during Linux operations, the kernel image stored in the SPI-NOR flash remains unaffected. This compressed file-system boasts high capacity, providing efficiency in storage utilization for the same root file-system size in flash.

Jffs2 File-System

In contrast, the jffs2 file-system resides in a dedicated partition within the SPI-NOR flash. Any alterations made to the root file-system are committed to the SPI-NOR flash. It's important to note that the performance of the jffs2 file-system may be suboptimal due to the necessity to read and modify the flash.

Partitions

Refer to figure of partitions of SPI-NOR flash below:

Note

For those seeking to adjust partitions, it is crucial to update the definition of the environment variable 'mtdparts' in U-Boot. This adjustment can be made in the header file located at:

boot/uboot/include/configs/pentagram_common_sp7350.h

The existing mtdparts is as follows:

mtdparts=f8000b00.spinor:96k@0(iboot)ro,192k(xboot)ro,128k(dtb)ro,768k(uboot)ro,864k(fip)ro,0x${sz_kernel}(kernel),-(rootfs);

SPI-NAND & 8-bit NAND flash

SP7350 supports ubifs (unsorted block image file-system) file-system as root file-system.

Standard 2k sector

Partitions, env, env_redund, dtb, kernel and rootfs, use standard 2k sector. 2048 bytes data plus 64 bytes parity comprise the sector. Each 512 bytes has 16 bits parity and is able to correct 4 errors.

1K60 sector

Partitions, nand_header, xboot1, uboot1, uboot2 and fip, use 1K60 sector. 1024 bytes data plus 105 bytes parity comprise the sector and stored in standard 2k sector. It is able to correct 60 bits in 1024 bytes of data. It has higher ability for error correction than standard sector.

Parititions

Refer to figure of partitions of SPI-NAND flash below:

Note

1. If you want to adjust partitions, please remember to modify define MTDPARTS_DEFAULT in file: 'boot/uboot/include/configs/pentagram_common_sp7350.h'

   #define MTDPARTS_DEFAULT sp_spinand.0:128k(nand_header),384k(xboot1),1664k(uboot1),1920k(uboot2),2m(fip),512k(env),512k(env_redund),256k(dtb),25m(kernel),32536k(rootfs)

2. Refer to struct BootProfileHeader defined in xboot/include/nand_boot/nandop.h for Boot Profile Header.

8-bit NAND flash

Note:

1. If you want to adjust partitions, please remember to modify define MTDPARTS_DEFAULT in file: 'boot/uboot/include/configs/pentagram_common_sp7350.h'

    #define MTDPARTS_DEFAULT sp_paranand.0:128k(nand_header),384k(xboot1),1664k(uboot1),1920k(uboot2),2m(fip),512k(env),512k(env_redund),256k(dtb),25m(kernel),32536k(rootfs)

2. Refer to struct BootProfileHeader defined in xboot/include/nand_boot/nandop.h for Boot Profile Header.

eMMC device

SD card

Files in boot partition

Refer to table below for files in root directory in boot partition: