hyper2kvm

Testing Converted Ubuntu 24.04.3 qcow2 on Fedora (GUI, BIOS)

This guide describes how to validate a converted Ubuntu 24.04.3 qcow2 image using KVM + libvirt on Fedora, booting with legacy BIOS (SeaBIOS) and attempting to land in graphical mode when available.

This is intended as a post-conversion smoke test after migrating a VMware VMDK to qcow2 and applying offline fixes (fstab, GRUB, initramfs, disk identifiers, etc.).

Prerequisites

Before migrating this platform, ensure:

✓ hyper2kvm installed (Installation Guide)
✓ Familiarity with Quick Start Guide
✓ Root/sudo access
✓ Source VM accessible

Host Requirements (Fedora)
Image Under Test (Ubuntu 24.04.3)
BIOS + GUI libvirt XML (Most Compatible)
Define and Start the VM
Connect to the Console / GUI
- Option 1: virt-viewer (recommended)
- Option 2: VNC
Expected Boot Sequence (Ubuntu 24.04.3)
Troubleshooting
Notes (24.04.x specifics)

Host Requirements (Fedora)

Install required virtualization tools:

sudo dnf install -y \
  libvirt \
  qemu-kvm \
  qemu-img \
  virt-viewer \
  libguestfs-tools

Enable libvirt and ensure the default network is active:

sudo systemctl enable --now libvirtd
sudo virsh net-start default 2>/dev/null || true

Image Under Test (Ubuntu 24.04.3)

/home/ssahani/by-path/out/ubuntu-24.04.3.qcow2

Assumptions:

Converted from VMware VMDK
Legacy BIOS capable (non-UEFI build)
Ubuntu 24.04.3 (Server or Desktop)
GUI may or may not be installed (console-only is still a valid success)

BIOS + GUI libvirt XML (Most Compatible)

This XML is conservative and generally works across Ubuntu images:

SeaBIOS (machine='pc')
Virtio disk + network
VNC graphics
VGA video model

cat >/tmp/ubuntu-24043-test.xml <<'EOF'
<domain type='kvm'>
  <name>ubuntu-24043-gui</name>

  <memory unit='MiB'>4096</memory>
  <vcpu>2</vcpu>

  <os>
    <type arch='x86_64' machine='pc'>hvm</type>
    <boot dev='hd'/>
  </os>

  <features>
    <acpi/>
    <apic/>
  </features>

  <cpu mode='host-passthrough'/>

  <devices>
    <!-- Disk -->
    <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2'/>
      <source file='/home/ssahani/by-path/out/ubuntu-24.04.3.qcow2'/>
      <target dev='vda' bus='virtio'/>
    </disk>

    <!-- Network -->
    <interface type='network'>
      <source network='default'/>
      <model type='virtio'/>
    </interface>

    <!-- Graphics -->
    <graphics type='vnc' autoport='yes' listen='127.0.0.1'/>

    <!-- Video -->
    <video>
      <model type='vga'/>
    </video>

    <input type='tablet' bus='usb'/>
  </devices>
</domain>
EOF

Define and Start the VM

Remove any existing domain with the same name:

sudo virsh destroy ubuntu-24043-gui 2>/dev/null || true
sudo virsh undefine ubuntu-24043-gui 2>/dev/null || true

Define and start:

sudo virsh define /tmp/ubuntu-24043-test.xml
sudo virsh start ubuntu-24043-gui

Connect to the Console / GUI

Option 1: virt-viewer (recommended)

virt-viewer ubuntu-24043-gui

Option 2: VNC

sudo virsh vncdisplay ubuntu-24043-gui

Connect to the displayed address, e.g.:

127.0.0.1:5901

Expected Boot Sequence (Ubuntu 24.04.3)

A successful boot typically shows:

SeaBIOS splash
GRUB menu
Ubuntu kernel + initramfs
Either:
- GDM login (Desktop / GUI installed), or
- Text login prompt (Server image)

Pass condition: any stable login prompt (GUI or console).

Troubleshooting

Drops to `grub>` prompt

Typical reasons:

Broken GRUB config
Wrong root device UUID
Missing /boot or broken /etc/fstab

Quick check from GRUB:

ls
ls (hd0,msdos1)/
ls (hd0,gpt1)/

Drops to `(initramfs)` shell

Likely causes:

root device mismatch (/dev/sda → vda)
missing virtio modules in initramfs (virtio_blk, virtio_pci, virtio_scsi)
bad /etc/fstab

Inside initramfs:

ls /dev/vd*
ls /dev/disk/by-uuid
cat /proc/cmdline

Offline fix (inside guest, once booted) usually is:

sudo update-initramfs -u
sudo update-grub

Black screen after GRUB

Try an alternate video model:

<model type='qxl' vram='65536'/>

or:

<model type='virtio'/>

“No bootable device”

Some converted installs expect SATA first.

Switch the disk bus for the first boot:

<target dev='sda' bus='sata'/>

After it boots and initramfs is confirmed sane, revert to virtio.

Boots but no GUI

Ubuntu Server defaults to:

systemctl get-default

Expected:

multi-user.target

This is not a failure.

If you want to verify GUI bits exist:

dpkg -l | egrep 'ubuntu-desktop|gdm3|gnome-shell'

Notes (24.04.x specifics)

Ubuntu 24.04.x typically uses GRUB for BIOS installs.
Netplan is expected; network coming up via DHCP on default libvirt network is the normal smoke-test baseline.
Console success is still a pass even if the original VM was “desktop-ish”.

Status: Smoke test template for Ubuntu 24.04.3 (BIOS, KVM/libvirt)

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