Create Ubuntu root file system

Preparatory work

Install qemu

Install emulator on Linux PC host:

sudo apt-get install qemu-user-static

Download and extract ubuntu-core

Users can go to ubuntu cdimg to download Ubuntu filesystem, choose to download ubuntu-base-16.04.1-base-arm64.tar.gz.

After downloading, create a temporary folder and unzip the root file system:

mkdir temp
sudo tar -xpf ubuntu-base-16.04.1-base-arm64.tar.gz -C temp

Modify the root file system

Preparatory

  • Preparatory network:

sudo cp -b /etc/resolv.conf temp/etc/resolv.conf
  • Preparatory qemu:

sudo cp /usr/bin/qemu-aarch64-static temp/usr/bin/
  • Enter the root file system for operation:

sudo chroot temp

Update and installation

  • Update:

apt update
apt upgrade
  • Install the functionality you need:

apt install vim git ....(Add as needed)
  • Install xubuntu

apt install xubuntu-desktop
  • Errors may occur:

E: Unable to locate package xxxx

The reason is that the installation package source is not added to /etc/apt/source.list, so the system can’t recognize the installation package. You can add a new source by yourself, or cover /etc/apt/source.list with the follow source.list:

# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.

deb http://ports.ubuntu.com/ubuntu-ports/ xenial main restricted
deb-src http://ports.ubuntu.com/ubuntu-ports/ xenial main restricted

## Major bug fix updates produced after the final release of the
## distribution.
deb http://ports.ubuntu.com/ubuntu-ports/ xenial-updates main restricted
deb-src http://ports.ubuntu.com/ubuntu-ports/ xenial-updates main restricted

## Uncomment the following two lines to add software from the 'universe'
## repository.
## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team. Also, please note that software in universe WILL NOT receive any
## review or updates from the Ubuntu security team.
deb http://ports.ubuntu.com/ubuntu-ports/ xenial universe
deb-src http://ports.ubuntu.com/ubuntu-ports/ xenial universe
deb http://ports.ubuntu.com/ubuntu-ports/ xenial-updates universe
deb-src http://ports.ubuntu.com/ubuntu-ports/ xenial-updates universe

## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
deb http://ports.ubuntu.com/ubuntu-ports/ xenial-backports main restricted
deb-src http://ports.ubuntu.com/ubuntu-ports/ xenial-backports main restricted

deb http://ports.ubuntu.com/ubuntu-ports/ xenial-security main restricted
deb-src http://ports.ubuntu.com/ubuntu-ports/ xenial-security main restricted
deb http://ports.ubuntu.com/ubuntu-ports/ xenial-security universe
deb-src http://ports.ubuntu.com/ubuntu-ports/ xenial-security universe
deb http://ports.ubuntu.com/ubuntu-ports/ xenial-security multiverse
deb-src http://ports.ubuntu.com/ubuntu-ports/ xenial-security multiverse

Add user and set password

  • Add user:

useradd -s '/bin/bash' -m -G adm,sudo firefly
  • Set the password for user:

passwd firefly
  • Set the password for root:

passwd root
  • Modify your root file system can exit:

exit

Make the root file system

Make your own root file system, depending on the size of your root file system, and note that the count value is modified based on the size of the temp folder:

dd if=/dev/zero of=linuxroot.img bs=1M count=4000
sudo mkfs.ext4 linuxroot.img
mkdir  rootfs
sudo mount linuxroot.img rootfs/
sudo cp -rfp temp/*  rootfs/
sudo umount rootfs/
e2fsck -p -f linuxroot.img
resize2fs  -M linuxroot.img

linuxroot.img is the final root file system image file.

FAQs

Q: After the root file system is loaded, the size is not normal and does not occupy the entire partition?

A: Execute the resize file system command after the system is loaded correctly:

 resize2fs /dev/mtd/by-name/linuxroot