Today the always in motion ppa ppa:snappy-dev/tools has landed support for overriding the dtb provided by the platform in the device part with one provided by the oem snap.

The package.yaml for the oem snap has been extended a bit to support this, an example follows for extending the am335x-boneblack platform.

The path hardware/dtb key in the yaml holds a value which is the path to the dtb withing the package, so in this case, I put mydtb.dtb in the root of the snap.

After that it’s just a snappy build away:

snappy build .

In order to get this properly provisioned, first we need the latest ubuntu-device-flash from the ppa:snappy-dev/tools, so let’s get it

sudo add-apt-repository ppa:snappy-dev/tools
sudo apt update
sudo apt install ubuntu-device-flash

And now we are ready to flash

sudo ubuntu-device-flash core \
    --platform am335x-boneblack \
    --size 4 \
    --install mydevice_sergiusens_1.0_all.snap
    --output bbb_custom.img

If everything went well, the boot partiton will hold your custom dtb instead of the default one, specifying --platform is required for this.

Please note that some of these things described here are subject to change.