Due to small differences between Mynewt's bundled bootloader and MCUboot, when building an app that will be run with MCUboot as the bootloader and which at the same time requires to use newtmgr to manage images, MCUboot must be added as a new dependency for this app.
First you need to add the repo to your project.yml:
project.repositories:
- mcuboot
repository.mcuboot:
type: github
vers: 0-dev
user: JuulLabs-OSS
repo: mcuboot
Then update your app's pkg.yml adding the extra dependency:
pkg.deps:
- "@mcuboot/boot/bootutil"
Also remove any dependency on boot/bootutil (mynewt's bundled bootloader) which might exist.
To configure MCUboot check all the options available in boot/mynewt/mcuboot_config/syscfg.yml.
Also, MCUboot uses a different image header struct as well as slightly different TLV structure, so images created by newt have to be generated in this new format. That is done by passing the extra parameter -2 as in:
newt create-image <target> <version> <pubkey> -2
Building with BOOT_SERIAL: 1 enables some basic management functionality like listing images and uploading a new image to slot0. The serial bootloader requires that mtu is set to a value that is less than or equal to 256. This can be done either by editing ~/.newtmgr.cp.json and setting the mtu for the connection profile, or specifying you connection string manually as in:
newtmgr --conntype serial --connstring "dev=/dev/ttyUSB0,mtu=256" image upload -e blinky.img
where /dev/ttyUSB0 is your serial port.