Bubblegum96-Snappy

Requirements

Make sure your build environment is based on Ubuntu 16.04. You need to install snappy tools.

sudo apt-get update
sudo apt-get install -y build-essential u-boot-tools debootstrap gcc-4.9-aarch64-linux-gnu device-tree-compiler
sudo apt-get install ubuntu-snappy snapcraft snapd

Notes:Bubblegum96 kernel can't be cross complied by gcc 5+ aarch64-linux-gnu, so you have to make soft link to gcc 4.9 related toolchain.

Build gadget snap

git clone https://github.com/blimjoe/Bubblegum96-Snappy
cd Bubblegum96-Snappy
cd gadget
snapcraft snap gadget

a gadget snap named bubblegum96-gadget_16.04-1.2_arm64.snap will be generated here

Build kernel snap

cd ~/Bubblegum96-Snappy/kernel
git clone https://github.com/uCRDev/linux.git
cd linux
git checkout bubblegum96-3.10
git am ../patchs/*

cd ../snappy
snapcraft --target-arch arm64 snap
#for 96board, it only supports uInitrd. Do a trick here, replace uInitrd with initrd.img
cd prime
mkimage -A arm64 -T ramdisk -C none -n "snappy initrd" -a 1ffffc0 -d initrd.img uInitrd
cp uInitrd initrd.img
cd ..
snapcraft --target-arch arm64 snap

Prepare model assertion

Before we can build image we need to prepare model assertion and sign it.
First prepare json file describing model assertion:
Example of model for Bubblegum96, ~/Bubblegum96-Snappy/image/TEMPLATE-model.json

{
 "type": "model",
 "authority-id": "<your accout id>",
 "brand-id": "<your accout id>",
 "series": "16",
 "model": "bubblegum96",
 "architecture": "arm64",
 "gadget": "bubblegum96-gadget",
 "kernel": "bubblegum96-kernel",
 "timestamp": "2016-11-22T12:00:00+00:00"
}

Timestamp is not necessary to modify, you can also exec $ date -Iseconds --utcto obtain the current timestamp.
You can find your account id here:https://myapps.developer.ubuntu.com/dev/account/

Sign model:

Before signing model, first make sure that you have valid key which has been registered with your accout.
If you do not have key, create new one:

snap create-key

Make sure you register key with your account:

snapcraft register-key

To check keys on your machine run

snap keys

Sign model assertion:

cd ~/Bubblegum96-Snappy/image
cat bubblegum96-model.json | snap sign -k your_key &> bubblegum96.model

Build bootable image

We will build image with ubuntu-image, install it with:

sudo snap install --stable --devmode ubuntu-image

Build image

cd ~/Bubblegum96-Snappy/image
cp ../gadget/bubblegum96-gadget_16.04-1.2_arm64.snap .
cp ../kernel/snappy/bubblegum96-kernel_3.10.99_arm64.snap .
sudo /snap/bin/ubuntu-image --channel stable --image-size 2G --extra-snaps bubblegum96-gadget_16.04-1.2_arm64.snap --extra-snaps bubblegum96-kernel_3.10.99_arm64.snap -o bubblegum96.img bubblegum96.model

Burn image to SD card

sudo dd if=bubblegum96.img of=/dev/sdX bs=32M
sync