Build Ubuntu Image#

This guide explains how to build a qcow2 virtual disk image from an Ubuntu 24.04 ISO using QEMU/KVM.

Prerequisites#

  1. Host packages installed:

    sudo apt update
sudo apt install -y qemu-system-x86 qemu-utils ovmf

  2. Ubuntu 24.04 ISO downloaded, ubuntu iso download, select ubuntu 24.04 desktop image, for example:

    • $HOME/ubuntu-24.04.4-desktop-amd64.iso

Create a qcow2 Disk#

Create a 128 GiB image file (adjust size as needed):

mkdir -p "$HOME/vm-images"
qemu-img create -f qcow2 "$HOME/vm-images/ubuntu24.04.qcow2" 128G

Check image information:

qemu-img info "$HOME/vm-images/ubuntu24.04.qcow2"

Install Ubuntu 24.04 into the qcow2 Image#

Boot the ISO installer and install the OS into the qcow2 disk:

qemu-system-x86_64 \
  -enable-kvm \
  -machine q35 \
  -cpu host \
  -smp 4 \
  -m 4G \
  -bios /usr/share/ovmf/OVMF.fd \
  -drive file="$HOME/vm-images/ubuntu24.04.qcow2",if=virtio,format=qcow2,cache=none \
  -cdrom "$HOME/ubuntu-24.04.4-desktop-amd64.iso" \
  -boot d \
  -netdev user,id=net0 \
  -device virtio-net-pci,netdev=net0 \
  -display gtk

then select Install Ubuntu to continue normal ubuntu image install process. After install process, ubuntu24.04.qcow2 is ready for use.