Issue with using prebuilt hex files for NSIB and MCUBOOT

[htn123]

Hello,

We're migrating our code base on the nRF52840 from nRF5 SDK to nRF Connect SDK v2.4.2 with NSIB as the first stage bootloader and MCUBOOT as second stage upgradable bootloader. It's working fine, we are able to update the MCUBOOT and application over BLE.

As a next step, we're exploring how to use the prebuilt hex files for both NSIB and MCUBOOT as we may not need to update the bootloader often and to speed up the building process rather than rebuilding them every time building the application code.

Configurations in the prj.conf are as followed:

# Immutable nRF secure boot
CONFIG_SECURE_BOOT=y
CONFIG_SB_SIGNING_KEY_FILE="b0_key.pem"
CONFIG_BUILD_S1_VARIANT=n
CONFIG_B0_BUILD_STRATEGY_USE_HEX_FILE=y
CONFIG_B0_HEX_FILE="b0.hex"

# Upgradable MCUboot
CONFIG_BOOTLOADER_MCUBOOT=y
CONFIG_BOOT_SIGNATURE_KEY_FILE="mcuboot_key.pem"
CONFIG_MCUBOOT_BUILD_STRATEGY_USE_HEX_FILE=y
CONFIG_MCUBOOT_HEX_FILE="mcuboot.hex"

b0.hex is taken from /build/b0/zephyr/zephyr.hex

mcuboot.hex is from /build/mcuboot/zephyr/zephyr.hex

I've also applied the current partition configuration file as static pm_static.yml

Build is successful. However when I tried to load the merged.hex to the chip it's not running.

I'm wondering if using prebuilt hex files for NSIB and MCUBOOT is fully supported ny NCS 2.4.2? If it is what I'm missing in the configuration to make it work?

Thanks.

[Einar Thorsrud]

Hi,

I need to look into this and get back to you, hopefully tomorrow.

[Einar Thorsrud]

Hi,

I have not got to the bottom of this yet. Using only CONFIG_MCUBOOT_BUILD_STRATEGY_USE_HEX_FILE without secure boot (so not B0/NSIB at all) works well, but with it, the build system does not handle it properly.

[htn123]

Hi Einar,

Have you had a chance to look at this? Thanks.

[Hieu]

Hi htn123,

Our apologies for the long wait. We have been short-handed and haven't been able to figure out what is wrong here yet. The Easter holiday will end next week, at which point the situation should improve, and one of us will follow-up with you as soon as possible.

Hieu

[Einar Thorsrud]

Hi,

It turns out that this issue was reported earlier as well, and has been investigated and some fixes and improvments have been made in this pull request. It may not make it in due to upcomming changes in the build system, but you can refer to that.