Linux Virtualization Guide

Complete beginner-friendly guide to virtualization on Linux, covering Arch Linux, CachyOS, and other distributions including QEMU/KVM, VirtualBox, Docker, container management, and GPU passthrough.

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Table of Contents

1. Understanding Virtualization
2. QEMU/KVM Setup
3. virt-manager Configuration
4. VirtualBox Setup
5. Docker Setup
6. Container Management
7. GPU Passthrough
8. Performance Optimization
9. Troubleshooting

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Understanding Virtualization

What is Virtualization?

Virtualization allows running multiple operating systems on one computer.

What it does:

• Creates VMs: Virtual machines (isolated environments)
• Runs multiple OS: Different operating systems simultaneously
• Isolates systems: VMs are separate from host
• Resource sharing: Shares CPU, RAM, disk with host

Virtualization Types

Full virtualization:

• QEMU/KVM: Hardware virtualization (Linux native)
• VMware: Commercial virtualization
• VirtualBox: Cross-platform virtualization

Container virtualization:

• Docker: Application containers
• Podman: Docker alternative
• LXC: System containers

Benefits

Why use virtualization:

• Testing: Test software safely
• Isolation: Isolate applications
• Multiple OS: Run different operating systems
• Development: Development environments
• Security: Isolated environments

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QEMU/KVM Setup

Check Hardware Support

Check CPU virtualization support:

# Check CPU features
lscpu | grep -E "vmx|svm"

# Or
grep -E "vmx|svm" /proc/cpuinfo

What this does:

• Checks CPU virtualization features
• vmx: Intel VT-x
• svm: AMD-V
• Need one of these

Install QEMU/KVM

Install packages:

# Arch/CachyOS
sudo pacman -S qemu-full virt-manager virt-viewer dnsmasq vde2 bridge-utils openbsd-netcat

# Install libvirt
sudo pacman -S libvirt libvirt-glib

# Enable services
sudo systemctl enable --now libvirtd.service

Debian/Ubuntu:

sudo apt install qemu-kvm libvirt-daemon-system virt-manager

Fedora:

sudo dnf install @virtualization

Add User to Group

Add to libvirt group:

# Add user to group
sudo usermod -aG libvirt username

# Log out and back in

virt-manager

GUI for VMs:

# Install virt-manager
sudo pacman -S virt-manager

# Launch
virt-manager

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VirtualBox Setup

Install VirtualBox

Install VirtualBox:

# Arch/CachyOS
sudo pacman -S virtualbox virtualbox-host-modules-arch

# Debian/Ubuntu
sudo apt install virtualbox

# Fedora
sudo dnf install VirtualBox

Enable VirtualBox

Load modules:

# Load modules
sudo modprobe vboxdrv

# Enable at boot
echo "vboxdrv" | sudo tee -a /etc/modules-load.d/virtualbox.conf

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Docker Setup

Install Docker

Install Docker:

# Arch/CachyOS
sudo pacman -S docker

# Enable service
sudo systemctl enable docker
sudo systemctl start docker

# Add user to group
sudo usermod -aG docker username

Debian/Ubuntu:

sudo apt install docker.io

Fedora:

sudo dnf install docker

Docker Compose

Install Docker Compose:

# Arch/CachyOS
sudo pacman -S docker-compose

# Or use plugin
sudo pacman -S docker-compose-plugin

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Container Management

Podman

Install Podman:

# Arch/CachyOS
sudo pacman -S podman

# Debian/Ubuntu
sudo apt install podman

# Fedora
sudo dnf install podman

Podman is a Docker alternative that doesn't require a daemon.

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GPU Passthrough

Prerequisites

Requirements:

• Two GPUs: One for host, one for VM
• IOMMU enabled: In BIOS/UEFI
• Kernel parameters: Enable IOMMU

Enable IOMMU

Edit GRUB:

# Edit GRUB
sudo vim /etc/default/grub

Add kernel parameters:

GRUB_CMDLINE_LINUX_DEFAULT="... intel_iommu=on"
# Or for AMD
GRUB_CMDLINE_LINUX_DEFAULT="... amd_iommu=on"

Regenerate:

sudo grub-mkconfig -o /boot/grub/grub.cfg

See Virt-manager Installation Guide for detailed GPU passthrough setup.

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Performance Optimization

CPU Pinning

Pin CPU cores:

# In virt-manager
# CPU > Topology > Pinning

Memory Allocation

Allocate memory:

# In virt-manager
# Memory > Allocate memory

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Troubleshooting

VM Not Starting

Check logs:

# Check libvirt logs
journalctl -u libvirtd

# Check VM logs
virsh dumpxml vm-name

Permission Issues

Check groups:

# Check groups
groups

# Should include: libvirt, kvm

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Summary

This guide covered virtualization for Arch Linux, CachyOS, and other distributions, including QEMU/KVM, VirtualBox, Docker, and GPU passthrough.

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Next Steps

• Virt-manager Installation Guide - Detailed virt-manager setup
• Container Orchestration - Container management
• Security Configuration - Security
• ArchWiki QEMU: https://wiki.archlinux.org/title/QEMU
• ArchWiki KVM: https://wiki.archlinux.org/title/KVM

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This guide covers Arch Linux, CachyOS, and other Linux distributions. For distribution-specific details, refer to your distribution's documentation.