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QEMU and VMM Setup

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tagsnote/cachyos

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Part of CachyOS Wiki Notes. From the official CachyOS wiki (last updated 2026-03-08).

QEMU and VMM Setup

Installing Virtual Machine Manager (VMM) + QEMU on CachyOS.

Packages

qemu-full, virt-manager, swtpm.

swtpm is only needed for Windows 11 guests when you have no compatible TPM module to pass through — otherwise you can add a TPM later during configuration.

# Install the packages
sudo pacman -S qemu-full virt-manager swtpm
 
# Force libvirt to use iptables
echo 'firewall_backend = "iptables"' | sudo tee -a /etc/libvirt/network.conf
 
# Add the user to the libvirt group
sudo usermod -aG libvirt $USER
 
# LXC backend (optional, for Linux containers)
systemctl enable --now libvirtd.service
 
# QEMU backend (for VMs)
systemctl enable --now libvirtd.socket
 
# Bring Internet up in a VM whenever one starts
sudo virsh net-autostart default
 
# Let the whole VM subnet route out — consider tighter rules for your threat model
sudo ufw route allow from 192.168.122.0/24
  • Config file touched: /etc/libvirt/network.conf.
  • Both backends can be enabled at once; they do not conflict.
  • Before creating a VM, the wiki defers to QEMU User Session.

Creating a VM in VMM

  • Edit -> Preferences -> ✅ Enable XML editing.
  • New VM (star/play icon, or File -> New Virtual Machine), choose Connection:, locate the .iso via Browse... (add a dedicated ISO pool with + (Add Pool); the user-session pool path lives in ~/.config/libvirt/).
  • If the OS is not autodetected, untick autodetection and pick the closest match manually (CachyOS = Arch Linux).
  • Set RAM and CPU cores (changeable later), create virtual storage (makes a .qcow2) or give a path.
  • Tick Customize configuration before install -> Finish.
  • Linux guests: in Overview confirm chipset Q35 and firmware UEFI.
  • Windows 11: confirm a TPM is present, else Add Hardware -> TPM (Emulated or Passthrough), then Finish.
  • Click Begin Installation.
  • Guest uses OpenGL and/or ships libvulkan → see EGL Headless 3D Acceleration and Virtio-Venus 3D Acceleration respectively.

Windows 11 performance notes

  • Install Virtio-Win drivers (RedHat) inside the guest.
  • Intel iGPU: look into GVT-g and MDEV. Intel iGPU + dGPU: GVT-d.
  • dGPU passthrough (iGPU + dGPU, or 2+ dGPUs): VFIO.

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