Some notes and tips on how to build and run virtual machines (VMs) with the Quick Emulator (QEMU) on Windows.

Preparation

1. Download and install QEMU: “QEMU is a generic and open source machine emulator and virtualizer”.

2. Performance tip for a Windows host: Open PowerShell (as Administrator!) and activate the Windows Hypervisor Platform feature (called “whpx” in QEMU):
   (At the end, you will be asked to reboot the computer to apply the changes.)

   > Enable-WindowsOptionalFeature -Online -FeatureName HypervisorPlatform -All
   

Create an empty disk image file for a VM

Use the program qemu-img (usually installed in C:\Program Files\qemu) with the command create to generate an empty disk image file (i.e. the “hard-disk” of the future VM).

Example (for a Haiku VM):

> qemu-img.exe create -f qcow2 C:\VMs\haiku.img 8G

• -f: Specifies the format of the disk image. qcow2 is the current and recommended QEMU image format: Most versatile, images are a bit smaller than with other formats.
• Followed by the filepath of the disk image.
• Followed by the max. size of the disk image in bytes.
  Supported optional suffixes: k or K for Kilobyte (1024), M for Megabyte (1024K), G for Gigabyte (1024M) and T for Terabyte (1024G) — b is ignored!
  The “virtual hard disk” isn’t created with its full maximum size: Here, it should be 8 Gigabytes; but the disk image file was after its creation only 193 Kilobytes big. And after the basic installation of Haiku from the ISO file (see below), the file grew to ~650 Megabytes.

Install an operating system to a VM

The program qemu-system-x86_64.exe (usually installed in C:\Program Files\qemu) is the main executable of QEMU for a x86-64-bit System running Windows: It provides the means to run a guest operating system on a Windows host.

Example: Install Haiku on a virtual x86-64-bit-PC

A virtual machine that represents a standard (x86-64-bit) PC and boots the Haiku ISO on boot from the “CD-ROM drive”:
(should all be on one line!)

> qemu-system-x86_64.exe -machine q35
                         -cpu host
                         -accel whpx
                         -drive file="C:\<path>\haiku.img"
                         -smp 4
                         -m 8G
                         -name Haiku
                         -usb
                         -device usb-tablet
                         -net user
                         -cdrom "C:\<path>\haiku-...-anyboot.iso" # only needed for installation
                         -boot menu=on                            # only needed for installation

• -machine: The emulated machine by name (use -machine help to list available machines).
  Defines the exact virtual hardware blueprint (chipset, bus architecture, and version-locked features) of a virtual machine. That way, VMs have a well-defined and stable environment. Example: pc: Standard PC (i440FX + PIIX, 1996); q35: Standard PC (Q35 + ICH9, 2009)
• -cpu host: Two ways to configure the CPU model with QEMU: Host passthrough (recommended/default to use the features/capabilities of the real processor) or Named model (e.g. IvyBridge was used in a Lenovo ThinkPad T430s from 2012/2014).
  (Host seems to require an accelerator…)
• -accel whpx: This is used to enable an accelerator. Depending on the target architecture, kvm, xen, hvf, nitro, nvmm, whpx, mshv or tcg can be available.
• -drive file=<path>: The -file= option defines which disk image (the “hard-disk”) to use with this drive — see previous section.
• -smp: “Simulate a SMP system with n CPUs initially present on the machine type board.”
• -m: “Sets guest startup RAM size to megs megabytes. Default is 128 MiB. Optionally, a suffix of “M” or “G” can be used to signify a value in megabytes or gigabytes respectively.”
• name: Sets the name of the guest (e.g. for the SDL window caption or for the VNC server).
• -usb: USB stuff…
• -device usb-tablet: “Pointer device that uses absolute coordinates (like a touchscreen). This means QEMU is able to report the mouse position without having to grab the mouse.”
• -net user: “Configure a host network backend” — no idea yet, what exactly user does or why everyone is using that…
• -cdrom <file>: “Use file as CD-ROM image on the default bus of the emulated machine […]” — e.g. for loading an ISO file for an OS installation.
• -boot: “Specify boot order drives as a string of drive letters. Valid drive letters depend on the target architecture. […]
  Interactive boot menus/prompts can be enabled via menu=on as far as firmware/BIOS supports them. The default is non-interactive boot.”

Optional:

• -k: Keyboard layout language (e.g. de or en-us); normally not needed on PC/Linux or PC/Windows hosts (the default is en-us).

Run the VM

After the OS is installed in the disk image file, run the same command as above (but without the parameters for the boot medium (-cdrom) and or boot order (-boot)) to start the VM (for daily use, either put it in a script, or use a GUI front-end).

Check (with Haiku R1b6) and conclusion (for now)

• ☑ Network/Internet/LAN: OK
• ☑ Mouse: OK (with -usb -device usb-tablet!)
• ☐ Performance: Using it with -accel whpx, but the fullscreen performance is terrible, even in lower resolution (and in window mode, the GUI of Haiku is tiny)!
  On the other hand: I’m currently testing it on a regular laptop with no special graphic/GPU support.

Maybe I haven’t yet found that one magic trick, but for now, I think I will leave it at that:
I know now how to create and run a VM with QEMU (in general), have documented the basics (for future endeavors) here, in my KB.
But my original plan, to use Haiku more often, in a VM, sadly doesn’t look so appealing at the moment…