hyper2kvm

# Testing Converted RHEL 10 qcow2 on Fedora (GUI, UEFI)

Table of Contents

• Prerequisites
• Host Requirements (Fedora)
• Image Under Test
• Why UEFI Needs a VARS Template (and Why Libvirt Yells)
• Put the qcow2 Where Libvirt Can Read It (Avoid Permission/SELinux Traps)
• UEFI + GUI libvirt XML (Known-Good)
• Define and Start the VM
• Connect to the GUI
  • Option 1: virt-viewer (recommended)
  • Option 2: SPICE display address
• Expected Boot Sequence
• Troubleshooting
  • “unable to find any master var store … OVMF_CODE.fd”
  • Permission denied reading qcow2
  • Black screen after GRUB
  • “No bootable device” / drops to UEFI shell
  • Boot logs needed (no GUI)
• Notes
• Next Steps
• Related Documentation

---

Prerequisites

Before migrating this platform, ensure:

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

This guide describes how to validate a converted RHEL 10 qcow2 image using KVM + libvirt on Fedora, booting directly into graphical (GUI) mode with UEFI (OVMF).

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

---

Host Requirements (Fedora)

Install required virtualization tools:

sudo dnf install -y \
  libvirt \
  qemu-kvm \
  qemu-img \
  virt-viewer \
  libguestfs-tools \
  edk2-ovmf

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

/home/ssahani/by-path/out/rhel10-fixed.qcow2

Assumptions:

• Converted from VMware VMDK
• UEFI guest (OVMF)
• RHEL 10 (or RHEL-like) with GRUB2 + BLS

---

Why UEFI Needs a VARS Template (and Why Libvirt Yells)

UEFI guests use two firmware blobs:

• OVMF_CODE.fd (read-only firmware code)
• OVMF_VARS.fd (mutable per-VM NVRAM “vars store”)

Libvirt must know a master VARS template so it can create a per-VM NVRAM file. On your host, the available firmware pairs are:

• /usr/share/edk2/ovmf/OVMF_CODE.fd
• /usr/share/edk2/ovmf/OVMF_VARS.fd
• (secureboot variants also exist, but we use non-secureboot by default)

---

Put the qcow2 Where Libvirt Can Read It (Avoid Permission/SELinux Traps)

Copy the image into the standard libvirt images directory:

sudo install -o qemu -g qemu -m 0640 \
  /home/ssahani/by-path/out/rhel10-fixed.qcow2 \
  /var/lib/libvirt/images/rhel10-fixed.qcow2

or

sudo cp /home/ssahani/by-path/out/rhel10-fixed.qcow2 \
  /var/lib/libvirt/images/

sudo chown qemu:qemu /var/lib/libvirt/images/rhel10-fixed.qcow2

Create the NVRAM directory (safe even if it already exists):

sudo mkdir -p /var/lib/libvirt/qemu/nvram

---

UEFI + GUI libvirt XML (Known-Good)

This XML is a conservative, reliable UEFI configuration:

• q35 machine
• OVMF UEFI firmware
• Explicit VARS template (prevents “master var store” errors)
• Virtio disk + network
• SPICE graphics + virtio video
• Serial console
• Virtio RNG (helps entropy-starved boots)

cat >/tmp/rhel10-uefi-gui.xml <<'EOF'
<domain type='kvm'>
  <name>rhel10-fixed-uefi-gui</name>

  <memory unit='MiB'>4096</memory>
  <currentMemory unit='MiB'>4096</currentMemory>
  <vcpu placement='static'>2</vcpu>

  <os>
    <type arch='x86_64' machine='q35'>hvm</type>

    <!-- UEFI firmware (non-secureboot) -->
    <loader readonly='yes' type='pflash'>/usr/share/edk2/ovmf/OVMF_CODE.fd</loader>

    <!-- Per-VM NVRAM file, copied from template on first boot -->
    <nvram template='/usr/share/edk2/ovmf/OVMF_VARS.fd'>/var/lib/libvirt/qemu/nvram/rhel10-fixed-uefi-gui_VARS.fd</nvram>

    <!-- Optional: enable temporarily for deep boot debugging -->
    <!-- <cmdline>rd.debug rd.shell loglevel=7 systemd.log_level=debug systemd.log_target=console</cmdline> -->
  </os>

  <features>
    <acpi/>
    <apic/>
    <vmport state='off'/>
  </features>

  <cpu mode='host-passthrough' check='none'/>

  <clock offset='utc'>
    <timer name='rtc' tickpolicy='catchup'/>
    <timer name='pit' tickpolicy='delay'/>
    <timer name='hpet' present='no'/>
  </clock>

  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>restart</on_crash>

  <devices>
    <emulator>/usr/bin/qemu-system-x86_64</emulator>

    <!-- USB controller (tablet input) -->
    <controller type='usb' index='0' model='qemu-xhci'/>

    <!-- Root disk -->
    <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2' cache='none' io='native' discard='unmap'/>
      <source file='/var/lib/libvirt/images/rhel10-fixed.qcow2'/>
      <target dev='vda' bus='virtio'/>
      <boot order='1'/>
    </disk>

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

    <!-- Serial console -->
    <serial type='pty'>
      <target port='0'/>
    </serial>
    <console type='pty'>
      <target type='serial' port='0'/>
    </console>

    <!-- Guest agent channel (install qemu-guest-agent inside guest) -->
    <channel type='unix'>
      <source mode='bind'/>
      <target type='virtio' name='org.qemu.guest_agent.0'/>
    </channel>

    <!-- Graphics: SPICE + virtio GPU -->
    <graphics type='spice' autoport='yes' listen='127.0.0.1'/>
    <video>
      <model type='virtio' heads='1'/>
    </video>

    <input type='tablet' bus='usb'/>

    <!-- RNG helps early boot -->
    <rng model='virtio'>
      <backend model='random'>/dev/urandom</backend>
    </rng>

    <memballoon model='virtio'/>
  </devices>
</domain>
EOF

---

Define and Start the VM

If a domain with the same name already exists, remove it first:

sudo virsh destroy rhel10-fixed-uefi-gui 2>/dev/null || true
sudo virsh undefine rhel10-fixed-uefi-gui --nvram 2>/dev/null || sudo virsh undefine rhel10-fixed-uefi-gui 2>/dev/null || true

Define and start the VM:

sudo virsh define /tmp/rhel10-uefi-gui.xml
sudo virsh start rhel10-fixed-uefi-gui

---

Connect to the GUI

Option 1: virt-viewer (recommended)

virt-viewer rhel10-fixed-uefi-gui

Option 2: SPICE display address

sudo virsh domdisplay rhel10-fixed-uefi-gui

---

Expected Boot Sequence

A successful boot should show:

1. OVMF splash (or quick handoff)
2. GRUB menu
3. RHEL kernel + initramfs (dracut)
4. Graphical login screen (gdm)

If this sequence completes, the image is boot-validated.

---

Troubleshooting

“unable to find any master var store … OVMF_CODE.fd”

Your XML is missing the VARS template link. Confirm these lines exist:

<loader readonly='yes' type='pflash'>/usr/share/edk2/ovmf/OVMF_CODE.fd</loader>
<nvram template='/usr/share/edk2/ovmf/OVMF_VARS.fd'>/var/lib/libvirt/qemu/nvram/NAME_VARS.fd</nvram>

Permission denied reading qcow2

Keep the qcow2 under /var/lib/libvirt/images/ with qemu:qemu ownership:

sudo chown qemu:qemu /var/lib/libvirt/images/rhel10-fixed.qcow2
sudo chmod 0640 /var/lib/libvirt/images/rhel10-fixed.qcow2

Black screen after GRUB

Try a simpler video model:

<video><model type='qxl'/></video>

or even:

<video><model type='vga'/></video>

“No bootable device” / drops to UEFI shell

Usually the EFI boot entry/NVRAM is missing or wrong. Two common fixes:

1) Ensure you’re using UEFI (OVMF) and the guest actually has an EFI System Partition. 2) From the guest’s GRUB, confirm BLS/root is correct and regenerate if needed.

Boot logs needed (no GUI)

Attach the serial console:

sudo virsh console rhel10-fixed-uefi-gui

Optionally enable debug kernel args in the XML <cmdline> (commented in the XML).

---

Notes

• This test uses UEFI + OVMF (not SeaBIOS)
• Explicit VARS template avoids the classic libvirt “master var store” failure
• Designed for VMware → KVM migrations where you want a quick, repeatable smoke test

---

Status: Verified working for RHEL 10 qcow2 (UEFI, GUI)

Next Steps

After migrating this platform:

• Test your VM - Validation examples
• Troubleshooting - Common issues
• Cookbook - More migration scenarios

Related Documentation

• Quick Start
• CLI Reference
• Architecture

This site is open source. Improve this page.