NAND update with customized trusted image

< How to manage OpenSTLinux projects in STM32CubeIDE

This article gives details about updating, using STM32CubeIDE, the NAND memory bootloader objects, located onto STM32MP157x-EV1 (e.g.).

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1 Overview[edit]

The different steps to update NAND with customized trusted image are the following ones:

  • Initialize the NAND with Starter Package image thanks to STM32CubeProgrammer.
  • Within STM32CubeIDE:
    • customize the trusted image, thanks to embedded STM32CubeMX generating device trees
    • compile corresponding Linux® device tree & bootloader images
    • update them on running STM32MP15 board
  • Check the new customization is correctly set up

All those steps are explained in chapters below.

2 Initialize NAND with Starter Package[edit]

Initialize the NAND with Starter Package image thanks to STM32CubeProgrammer.
For that select the Starter package corresponding to the targeted STM32MP1 board and jump to chapter Downloading the image and flashing it on the board (e.g. here for STM32MP15 Evaluation board).

Before executing the next step, check the bootloader version, visible in boot messages:

  • TF-A BL2 version, booting from NAND memory
NAND initial setting: TF-A BL2 version


  • U-boot version & extlinux.conf file used, booting from NAND memory
NAND initial setting: U-boot version & extlinux.conf


  • extlinux.conf content before update
NAND initial setting: extlinux.conf content


3 Customize bootloader images and update them on running STM32MP15 board[edit]

3.1 Build the trusted image inside STM32CubeIDE with the new expected device trees[edit]

After customization of hardware resources within embedded STM32CubeMX, new device trees for Linux® and for bootloader are generated.
Next step is to build an update of the new trusted image; this is covered also within STM32CubeIDE with:

Note that for Linux®, only device tree has to be updated as described hereafter.

3.2 STM32MP1 board update with new Linux® device tree[edit]

In this step, STM32MP15 board is up and running with network access: target status is green.
After having compiled device tree generated by STM32CubeMX , you need to :

  • update MP15 target bootfs with new .dtb under /boot
  • and adjust /boot/nand0_extlinux/stm32mp157c-ev1_extlinux.conf in order to declare new device tree and set it as default.

For that, follow steps explained below:

  • select the Cortex-A Linux® Deployment shortcut configuration available from Linux® project Run As... menu.
Linux® deployment configuration


  • Validate your choice and use Run button. You get in a dedicated Linux® Deployment console a message like this:
NAND Linux® deployment message


  • Check extlinux.conf content after NAND Linux® device tree update (DEFAULT and LABEL have changed)
NAND Linux® device tree update


3.3 STM32MP1 board update with new bootloader images[edit]

In this step, STM32MP15 board is up and running with network access: target status is green.
After having built customized bootloader images, you need to update STM32MP1 board.

  • Select Cortex-A project in STM32CubeIDE and click right to get Cortex-A Bootloader Deployment shortcut.
Bootloader update shortcut


Connection is automatically set and you need to scan STM32MP15 target storage, thanks to Scan... button.
This storage list depends on the board and on the used boot storage. Then, select the storage to update (NAND #0 here) and the TF-A BL2 & FIP image to update from FIP_artifacts/ .
Here is the corresponding STM32 Cortex-A Bootloader Deployment configuration:

NAND Bootloader deployment configuration


  • Click on Run, you get in a dedicated Bootloader Deployment console following message:
NAND Bootloader deployment message


4 Check new bootloader version after customization with STM32CubeIDE[edit]

After the update, the new bootloader version can be checked by comparing version appearing in boot messages  : TF-A BL2 and U-Boot versions are modified and Linux® uses the generated device tree.
Here are the new boot messages :

  • TF-A BL2 updated version, booting from NAND memory
NAND updated TF-A BL2 version


  • U-Boot updated version & Linux® device tree, booting from NAND memory
NAND updated U-Boot version & Linux® device tree


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