SDAA437 July   2026 TDA4VE-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1 Introduction
    1. 1.1 Motivation
    2. 1.2 Scope
    3. 1.3 Target Boot Architecture
  5. 2 Background
    1. 2.1 J721S2 Boot Flow
    2. 2.2 OSPI NOR Flash Overview
    3. 2.3 UBI and UBIFS Overview
  6. 3 OSPI Flash Layout
    1. 3.1 Partition Layout
    2. 3.2 Bootloader Partitions
    3. 3.3 Root Filesystem Partition
  7. 4 Flashing Boot Components
    1. 4.1 Boot Components Overview
    2. 4.2 Identifying OSPI MTD Partitions
    3. 4.3 Flashing Boot Components into OSPI NOR Flash
    4. 4.4 Verifying Boot Components
  8. 5 Creating a UBIFS Root Filesystem
    1. 5.1 Preparing the RootFS Partition
    2. 5.2 Creating a UBI Device
    3. 5.3 Creating a UBIFS Volume
    4. 5.4 Verifying UBIFS Operation
  9. 6 Storing Linux Boot Artifacts in UBIFS
    1. 6.1 Mounting the UBIFS Root Filesystem Volume
    2. 6.2 Creating the Root Filesystem Structure with BusyBox
    3. 6.3 Verifying BusyBox Execution
    4. 6.4 Creating BusyBox Command Links
    5. 6.5 Creating the init Script
    6. 6.6 Testing the Root Filesystem Using chroot
    7. 6.7 Copying the Linux Kernel Image and DTB
  10. 7 Configuring Linux Boot from UBIFS
    1. 7.1 Configuring Boot Arguments
    2. 7.2 Loading the Kernel and DTB from UBIFS
    3. 7.3 Testing Linux Boot
    4. 7.4 Creating a Reusable Boot Command
  11. 8 Booting Linux Entirely from OSPI NOR Flash
    1. 8.1 Automating the Boot Sequence in U-Boot
    2. 8.2 End-to-End Boot Flow
  12. 9 Summary
  13. 10References

1.2 Scope

The objective of this application note is to demonstrate and verify Linux boot from OSPI NOR flash on the J721S2 platform without relying on eMMC storage.

The following items are discussed.

  • Creating a UBI/UBIFS root filesystem within OSPI NOR flash
  • Building and validating a minimal Linux root filesystem
  • Storing the Linux kernel image and DTB in UBIFS
  • Loading the kernel image and DTB from UBIFS using U-Boot
  • Booting Linux with a UBIFS root filesystem
  • Booting the complete system from OSPI NOR flash

The procedures described in this document were validated on the J721S2 EVM using Processor SDK Linux.