Question about MCUboot version

[QuentinD]

Hello,

In my project, I have b0+mcuboot+app to be able to update the bootloader and the application.

I am contacting you because I have trouble understanding the difference between SB_CONFIG_SECURE_BOOT_MCUBOOT_VERSION, CONFIG_FW_INFO_FIRMWARE_VERSION and the VERSION file located in \bootloader\mcuboot\boot\zephyr.
I know that the VERSION file corresponds to the version of the mcuboot but then what do SB_CONFIG_SECURE_BOOT_MCUBOOT_VERSION and CONFIG_FW_INFO_FIRMWARE_VERSION correspond to? What are the values ​​that should be given to them?

Thank you

[Amanda Hsieh]

Hi, 

When MCUboot updates are enabled, the firmware embeds the nRF Secure Immutable Bootloader version using the CONFIG_FW_INFO_FIRMWARE_VERSION Kconfig option. However, during an update, MCUboot does not check this version; it only checks the MCUboot package version.

You can set the MCUboot update package version in sysbuild with SB_CONFIG_SECURE_BOOT_MCUBOOT_VERSION. You must increase this version number when deploying an MCUboot update. If the version in the update is lower than the current version, MCUboot will reject the update and not transfer it to the opposing secure boot firmware slot.

Using a VERSION file allows you to independently configure the version value for each build instance of the application.

See MCUboot update package version, Image versions, and Application version management.

Regards,
Amanda H.