Testing the bootloader chain

To test either of the bootloaders and the secure bootloader chain, build and program them with any sample as described in Adding a bootloader chain.

By default, both nRF Secure Immutable Bootloader and MCUboot print information to their serial output on boot. This output includes information about the validation of images in its slots, as well as firmware-specific information if using CONFIG_FW_INFO with the nRF Secure Immutable Bootloader. To see this output:

  1. Connect to the kit with a terminal emulator (for example, PuTTY). See How to connect with PuTTY for the required settings.

  2. Reset the development kit.

  3. Observe that each bootloader in the chain prints its information upon boot (some values may vary by build):

Attempting to boot slot 0.
Attempting to boot from address 0x9000.
Verifying signature against key 0.
Hash: 0xc0...71
Firmware signature verified.
Firmware version 1
Setting monotonic counter (version: 1, slot: 0)

When compiled with minimal configurations that disable logging output, such as prj_minimal.conf, you can disable the bootloader information output altogether or per-bootloader. Refer to the source code directories of each bootloader to see what minimal configuration options are already available, or add them through a custom Kconfig fragment if desired.