Build Ubuntu Rfs

Use miniroot to Create and Load System

Homepage of miniroot is:

http://androtab.info/miniroot/

 miniroot is a tiny shell environment, used to create and load root
file system, such as Ubuntu, Gentoo and Arch Linux, etc. These systems
can be reside in root or sub directories on any supported storage
device. This means that we can install multiple OS in eMMC Flash, TF
card or USB disk, and boot from one of them. Very handy to switch OS,
no need to modify and flash parameter file (parameter file is used to
specify the important partition info of flash storage).miniroot needs
serial line to debug, please see

Serial Debug

. Additionally, we need ethernet to download system image when
install. Of course, it can also be downloaded first on host PC, then
copied to the removable storage device for later use.

Before You Start

Important! Please backup data first, whether in the development board
or removable storage devices, in case of any data lost due to mistaken
operations or unforeseen accidents.

First, make sure the board is already flashed with working images.
Then download following image files:

misc.img

linux-boot-miniroot.img

If Android or dual system is installed, then flash linux-boot-
miniroot.img to recovery partition, misc.img to misc misc partition
respectively.If pure Linux is installed, flash linux-boot-miniroot.img
to boot partition. miniroot will drop you to a shell, after first boot
up. You can see the prompt in the serial terminal:

   miniroot#

Then start to configure the network. If it is DHCP:

   miniroot# udhcpc

Otherwise, you need to specify network parameters manually. (Replace
192.168.1.* with the address actually used):

   miniroot# ip addr add 192.168.1.2/24 broadcast + dev eth0
   miniroot# ip link set dev eth0 up
   miniroot# ip route add default via 192.168.1.1
   miniroot# echo nameserver 192.168.1.1 > /etc/resolv.conf

Miniroot supports booting from sub directory. You can have the OS
installed in the favorite location, and boot from it. Multiple OS boot
support is therefore just a piece of cake.Note that in Firefly-RK3128,
the debug serial port has pins multiplexed with the TF card interface.
Therefore, the TF card must be plugged out before using the debug
serial port.Below, we'll use the first parition of USB disk to install
the OS. Create ext4 filesystem and then mount it to /mnt, then extract
Ubuntu files:

   miniroot# mkfs.ext4 -E nodiscard /dev/sda1
   miniroot# mount /dev/sda1 /mnt

Please make sure the partition has sufficient free space (4G and
above).

Download and Extract ubuntu-core

ubuntu-core is the minimum root file system. You can setup desktop or
server environment later after install.Download and extract to /mnt:

   miniroot# cd /mnt
   miniroot# wget -P /mnt http://cdimage.ubuntu.com/ubuntu-core/releases/15.04/release/ubuntu-core-15.04-core-armhf.tar.gzminiroot# mkdir /mnt/ubuntu
   miniroot# tar -xpzf /mnt/ubuntu-core-15.04-core-armhf.tar.gz -C /mnt/ubuntu

Boot Ubuntu

Set host name

   miniroot# echo firefly > /mnt/ubuntu/etc/hostname
   miniroot# sed -e 's/miniroot/firefly/' < /etc/hosts > /mnt/ubuntu/etc/hosts

Or serial console is not convenient, you can create new user account
(account and password are both "ubuntu" in this case):

   miniroot# chroot /mnt/ubuntu useradd -G sudo -m -s /bin/bash ubuntu
   miniroot# echo ubuntu:ubuntu | chroot /mnt/ubuntu chpasswd

Install core packages

   miniroot# mount -t proc none /mnt/ubuntu/proc
   miniroot# mount -t devtmpfs none /mnt/ubuntu/dev
   miniroot# cp /etc/resolv.conf /mnt/ubuntu/etc/
   miniroot# chroot /mnt/ubuntu /bin/bash
   root@miniroot:/# apt-get update
   root@miniroot:/# apt-get install --no-install-recommends sudo iproute net-tools isc-dhcp-client
   root@miniroot:/# exit
   miniroot# rm /mnt/ubuntu/etc/resolv.conf
   miniroot# umount /mnt/ubuntu/proc
   miniroot# umount /mnt/ubuntu/dev

Boot Ubuntu

   miniroot# boot /mnt:/ubuntu /lib/systemd/systemd

Tips: If root device is not mounted, you can replace the mount
directory before the colon with the root device. Miniroot will mount
the root device automatically:

   miniroot# boot /dev/sda1:/ubuntu /lib/systemd/systemd

Initial Configuration

Login by serial console

   Ubuntu 15.04 ubuntu ttyFIQ0
   ubuntu login: ubuntu
   Password: ubuntu
   Last login: Tue May 26 08:11:03 UTC 2015 on ttyFIQ0
   Welcome to Ubuntu 15.04 (GNU/Linux 3.10.0 armv7l)
   Documentation:  https://help.ubuntu.com/
   ubuntu@ubuntu:~$ sudo -s
   [sudo] password for ubuntu: ubuntu 
   root@ubuntu:~#

Setup network（DHCP）

   root@ubuntu:~# echo auto eth0 > /etc/network/interfaces.d/eth0
   root@ubuntu:~# echo iface eth0 inet dhcp >> /etc/network/interfaces.d/eth0
   root@ubuntu:~# ln -fs ../run/resolvconf/resolv.conf /etc/resolv.conf
   root@ubuntu:~# ifup eth0

Upgrade packages

   root@ubuntu:~# cp /etc/apt/sources.list /etc/apt/sources.list.orig
   root@ubuntu:~# sed -i -e 's,^# deb\(.*\)$,deb\1,g' /etc/apt/sources.list
   root@ubuntu:~# apt-get update
   root@ubuntu:~# apt-get dist-upgrade

Reboot

   root@ubuntu:~# reboot

Enter miniroot, edit the environment variables, and set the boot
parameters of Ubuntu:

   miniroot# editenv
   boot=/dev/sda1:/ubuntu
   init=/lib/systemd/systemd
   autoboot=1

Save the environment variables and reboot

   miniroot# saveenv
   miniroot# reboot -f

Install Packages

Install Lubuntu (LXDE):

   root@ubuntu:~# apt-get install lubuntu-desktop

Make the RFS

Plug USB disk out, and plug it to the host, mount it to  /mnt. Check
the space needed for the rfs:

   sudo du -hs /mnt/ubuntu

Clean /mnt/ubuntu, especially logging and temporary files and
directories.Create empty disk image file. For example, create 1GB rfs
empty image:

   cd /new/firmware/work/dir/
   dd if=/dev/zero of=linuxroot.img bs=1M count=1024
   # format to ext4 filesystem, labeled as linuxroot
   mkfs.ext4 -F -L linuxroot linuxroot.img

Mount, transfer data, then unmount:

   mount -o loop linuxroot.img /opt
   cp -a /mnt/ubuntu/* /opt/
   umount /opt

The final root filesystem linuxroot.img is ready to serve.

FAQ

How to go back to normal boot

If you flash misc.img to the misc partition, the board will boot the
system in recovery partition. To revert to normal boot, there are two
ways:

Download misc_zero.img, and flash to misc partition.

Under a Linux shell in the board, run:

   sudo dd if=/dev/zero of=/dev/block/mtd/by-name/misc bs=16K count=3
   sudo sync
   sudo reboot

Reference

Ubuntu 14.04 LTS with miniroot