FLUG: QEMU lightning talk

Thomas Rasmussen

15. June, 2023

About me

Thomas Rasmussen

I work as a software developer/consultant at Gennemtænkt IT

- working primarily on the JVM using Groovy and Grails

QEMU

A generic and open source machine emulator and virtualizer

Full-system emulation - Run operating systems for any machine, on any supported architecture
User-mode emulation - Run programs for another Linux/BSD target, on any supported architecture
Virtualization - Run KVM and Xen virtual machines with near native performance

Qemu.org

Install

Pre install

Verify virtualization is enabled

$ egrep -c '(vmx|svm)' /proc/cpuinfo
12

vmx = Intel

svm = AMD

If the value is zero check your BIOS settings…

Installing

Install QEMU (the virtualization part)

$ sudo apt install qemu-kvm

For emulating different CPU architectures install

$ sudo apt install qemu-user

Run applications for different CPU architectures

X86
ARM 32
ARM 64 (aarch64)
MIPS
PowerPC
RISC-V
S390x
Sparc 32
Sparc 64
System targets …

Examples of different architectures

My system is an Intel/AMD X86_64 based system running Ubuntu

$ uname -a
Linux 6.2.0-20-generic #20-Ubuntu SMP PREEMPT_DYNAMIC Thu Apr  6 2023 x86_64 x86_64 x86_64 GNU/Linux

A simple “hello world” program written in Go-lang

Hello world in Go-lang - download src

and cross compiled for different CPU architectures and operating systems:

Script for compiling - download src

$ file hello-arm64
hello-arm64: ELF 64-bit LSB executable, ARM aarch64, version 1 (SYSV), statically linked, Go BuildID=ZgcKY7b7tAM4fTfkEmcR..., not stripped

$ file hello-arm32
hello-arm32: ELF 32-bit LSB executable, ARM, EABI5 version 1 (SYSV), statically linked, Go BuildID=6mnYLXKGBcNxSMYhaM56..., not stripped

$ file hello-x84
hello: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), statically linked, Go BuildID=e-dT_OvB22dfzXKqhiNI..., not stripped

$ file hello-win.exe
hello-win.exe: PE32+ executable (console) x86-64 (stripped to external PDB), for MS Windows, 13 sections

Examples of different architectures - running …

Running the different “hello world” programs

$ ./hello-x64
Hello world! From: linux on amd64

$ ./hello-arm32
bash: ./hello-arm32: cannot execute binary file: Exec format error

$ qemu-arm hello-arm32
Hello world! From: linux on arm

$ qemu-arm hello-arm64
qemu-arm: hello-arm64: Invalid ELF image for this architecture

$ qemu-aarch64 hello-arm64
Hello world! From: linux on arm64

$ ./hello-win.exe
bash: ./hello-win.exe: cannot execute binary file: Exec format error

$ qemu-x86_64 hello-win.exe
Error while loading hello-win.exe: Exec format error

Running other full systems

QEMU does more than letting us run applikation written for different CPU architectures it also lets us run other complete Operating Systems

Kubuntu

Kubuntu 22.04.2 Desktop AMD64 ISO

Get Kubuntu

Windows

Get a Windows 11 development environment

Download a virtual machine

I downloaded the WinDev2305Eval.VirtualBox.zip for Virtualbox

QEMU doesn’t run Virtualbox .ova files, they need to be converted from .ova to .qcow2 (QEMU Copy-On-Write version 2) format.

$ unzip WinDev2305Eval.VirtualBox.zip
$ tar -xvf WinDev2305Eval.ova
$ ls
  WinDev2305Eval.ova
  WinDev2305Eval-disk001.vmdk
  WinDev2305Eval.ovf
$ qemu-img convert WinDev2305Eval-disk001.vmdk WinDev2305Eval.qcow2 -O qcow2

How to convert ova image to qcow2

Running: Kubuntu

Create .img file (virtual harddisk)

$ qemu-img create -f qcow2 Image.img 10G

Using the cli

$ qemu-system-x86_64 -enable-kvm -cdrom ../iso/kubuntu-22.04.2-desktop-amd64.iso -boot menu=on \
    -drive file=Image.img \
    -m 4G -cpu host -smp 4 -vga virtio -display sdl,gl=on \

-m memory/RAM

-cpu host - Host CPU og guest are the same in this case so no emulation needed

-smp number of CPU cores

-vga better graphichs through virtio

-display sdl gl=on enables OpenGL for smoother graphics

And many many more options…

Running: Windows 11

We’ll use the QEMU GUI this time

Install relevant utils

$ sudo apt -y install bridge-utils cpu-checker libvirt-clients libvirt-daemon

Start libvirtd for virt-manager

$ sudo systemctl start libvirtd
$ sudo systemctl enable libvirtd

Add user to relevant groups

$ sudo usermod -aG libvirt $USER
$ sudo usermod -aG kvm $USER
$ groups
thomas adm cdrom sudo dip plugdev kvm lpadmin lxd sambashare docker libvirt

Install virt-manager

$ sudo apt install virt-manager

Virt-Manager

$ virt-manager

Create virtual machine

Locate ISO or disc image

virt-manager looks for images at this location

/var/lib/libvirt/images

Select disc image

Select the virtual machine you want to run

Windows 11

Shared files using USB sticks

From the Virt-Manager menu select

Virtual Machine > Redirect USB device

And select the USB drive from the list

Runnig the hello-win.exe

We can now run the for Windows compiled “hello world” program

Shared folders between host and guest OS

It is also possible to mount folders on the host machine into the guest machine using 9p virtio as the transport for sharing files

Example Sharing Host files with the Guest

Snapshots

break - restore - retry…

QEMU supports snapshots - if you break something while testing just go back to previous snapshot

QEMU also supports temporary snapshots, where any changes made to the virtual machine while it is running are written to temporary files

Create snapshot

Other use cases

Coreboot - testing and developing open source boot firmware

Coreboot test image using QEMU

Coreboot QEMU

Coreboot, u-root and Systemboot

Help…

CTRL + ALT + G : Get your mouse back from the emulator

CTRL + ALT F : Fullscreen emulator window