We provide Fenix to build the Ubuntu OS images easily.
You can follow the steps below:

Install essential dependencies.

$ sudo apt update
$ sudo apt install git make lsb-release qemu-user-static

Clone the Fenix repository to somewhere, e.g. ~/project

$ mkdir ~/project
$ cd ~/project/
$ git clone --depth 1 https://github.com/khadas/fenix

You should setup the build environment first.

For example: Board type, Linux version, distribution.

$ cd ~/project/fenix
$ source env/setenv.sh

Just type make to start build.

$ make uboot

$ make uboot-deb

$ make kernel

$ make kernel-deb

$ make gpu-deb

$ make board-deb

$ make debs

$ make uboot-image

$ make kernel-clean

$ make kernel-config

$ make kernel-saveconfig

$ make uboot-clean

You can get help messages by executing make help:

$ make help
Fenix scripts help messages:
  all                   - Create image according to environment.
  kernel                - Build linux kernel.
  kernel-clean          - Clean linux source tree.
  kernel-config         - Show linux menuconfig.
  kernel-saveconfig     - Save linux defconfig.
  uboot                 - Build u-boot.
  uboot-clean           - Clean u-boot source tree.
  uboot-deb             - Build u-boot debian package.
  uboot-image           - Build minimal image only with u-boot.
  kernel-deb            - Build linux debian package.
  board-deb             - Build board debian package.
  common-deb            - Build common debian package.
  desktop-deb           - Build desktop debian package.
  gpu-deb               - Build gpu debian package.
  debs                  - Build all debian packages.
  image                 - Pack update image.
  clean                 - Cleanup.
  info                  - Display current environment.
  get-make-params       - Get available make parameters.

Options for building:

• NO_CCACHE - ccache option
  • NO_CCACHE=no make - Enable ccache default
  • NO_CCACHE=yes make - Disable ccache

• COMPRESS_IMAGE - compress build image option
  • COMPRESS_IMAGE=no make - Don't compress default
  • COMPRESS_IMAGE=yes make - Compress image with xz

• BUILD_TYPE - image build type option
  • BUILD_TYPE=develop make - Develop build
  • BUILD_TYPE=release make - Release build

You can also choose to build the OS image in a Docker container.

Please refer to Docker Documentation.

$ sudo usermod -aG docker $USER

$ docker run hello-world

If you see the following print-out, Docker has installed successfully:

Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
ca4f61b1923c: Pull complete
Digest: sha256:be0cd392e45be79ffeffa6b05338b98ebb16c87b255f48e297ec7f98e123905c
Status: Downloaded newer image for hello-world:latest
 
Hello from Docker!
This message shows that your installation appears to be working correctly.
 
To generate this message, Docker took the following steps:
 1. The Docker client contacted the Docker daemon.
 2. The Docker daemon pulled the "hello-world" image from the Docker Hub.
    (amd64)
 3. The Docker daemon created a new container from that image which runs the
    executable that produces the output you are currently reading.
 4. The Docker daemon streamed that output to the Docker client, which sent it
    to your terminal.
 
To try something more ambitious, you can run an Ubuntu container with:
 $ docker run -it ubuntu bash
 
Share images, automate workflows, and more with a free Docker ID:
 https://cloud.docker.com/
 
For more examples and ideas, visit:
 https://docs.docker.com/engine/userguide/

Get Docker image:

$ cd ~/project/fenix
$ docker pull numbqq/fenix:latest

Build image in Docker:

$ docker run -it --name fenix -v $(pwd):/home/khadas/fenix \
             -v /etc/localtime:/etc/localtime:ro \
             -v /etc/timezone:/etc/timezone:ro \
             -v $HOME/.ccache:/home/khadas/.ccache --privileged \
             --device=/dev/loop-control:/dev/loop-control \
             --device=/dev/loop0:/dev/loop0 --cap-add SYS_ADMIN \
             numbqq/fenix

Start your build from inside the Docker container.

khadas@919cab43f66d:~/fenix$ source env/setenv.sh
khadas@919cab43f66d:~/fenix$ make

Restart the Docker container.

$ docker start fenix
$ docker exec -ti fenix bash