build of port for pandaboard to Ubuntu core series 16 Snappy Ubuntu Core

builder: build board image for Ubuntu core via makefiles, and that includes Gadget snap and Kernel snap.
prebuild: prebuild iamge for test purpose.

Make sure your build environment is based on Ubuntu 16.04 or later. Then, you need to install snappy tools, for creating image.

To build all parts, a couple of dependencies are required. On Ubuntu you can install all build dependencies with the following command.

sudo apt-get update
sudo apt-get install -y build-essential u-boot-tools lzop debootstrap gcc-4.8-arm-linux-gnueabihf device-tree-compiler
sudo apt-get install -y ubuntu-snappy snapcraft
sudo snap install --devmode --edge ubuntu-image

Note: snapcraft is broken in Ubuntu 16.04 LTS. See https://bugs.launchpad.net/snapcraft/+bug/1740882

Note: there is no 4.x cross toolchain available in Ubuntu 16.04 LTS. Use the linaro toolchain instead:

wget https://releases.linaro.org/components/toolchain/binaries/4.9-2016.02/arm-linux-gnueabihf/gcc-linaro-4.9-2016.02-x86_64_arm-linux-gnueabihf.tar.xz
unxz gcc-linaro-4.9-2016.02-x86_64_arm-linux-gnueabihf.tar.xz
export PATH=$PWD/gcc-linaro-4.9-2016.02-x86_64_arm-linux-gnueabihf/bin/

You can test if the right compiler is setup by checking that you get a 4.9 compiler version like:

arm-linux-gnueabihf-gcc --version
arm-linux-gnueabihf-gcc (Linaro GCC 4.9-2016.02) 4.9.4 20151028 (prerelease)
Copyright (C) 2015 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Ubuntu kernel can't be cross compiled by gcc 5+ arm-linux-gnueabihf, so you have to make soft link to gcc 4.8 related toolchain.

ubuntu-image is still in early days of development, so it has to be installed in devmode and best from edge or beta channel

Generate ssh key-pair if you did not have one

ssh-keygen -t rsa

Build an image by fetching essential snaps from Ubuntu store

./build-snappy.sh

A Makefile is provided to build Snappy, Gadget snap, U-Boot, Kernel snap from source. The sources will be cloned into local folders if not there already.

To build it all, just run make snappy. This will produce a Snappy image, a gadget snap pandaboard_x.y_all.snap and a kernel snap pandaboard-kernel_x.y.z.snap for device part, which can be used to build your own Snappy image.

You can build custom image with extra snaps included,

/snap/bin/ubuntu-image \
	-c <channel for core image> \
	--image-size 4G \
	--extra-snaps pandaboard_<gadget snap version>_armhf.snap \
	--extra-snaps pandaboard-kernel_<kernel snap version>_armhf.snap \
	--extra-snaps snapweb \
	--extra-snaps <more addoitional snaps>
	-o pandaboard-<some version to identify new image>.img \
	pandaboard.model

make u-boot

make gadget

make kernelsnap

To rebuild the snappy or other parts, just type make clean or make clean-{prefix}. The prefix will be u-boot, gadget, kernelsnap, etc.

Before dd, we suggest the SD card storage should be umounted to safely clean up.

xzcat ${image} | pv | sudo dd of=/dev/${device} bs=32M ; sync

Before snapcraft begins to compile the snap, it may pop up an error as below:

No valid credentials found. Have you run "snapcraft login"?

First, make sure you have Ubuntu One SSO and ability to get 2nd factor from Authenticator, then execute the following command:

snapcraft login