nixpkgs/nixos/doc/manual/installation/installing-virtualbox-guest.section.md

Installing in a VirtualBox guest

Installing NixOS into a VirtualBox guest is convenient for users who want to try NixOS without installing it on bare metal. If you want to set up a VirtualBox guest, follow these instructions:

1. Add a New Machine in VirtualBox with OS Type "Linux / Other Linux"

2. Base Memory Size: 768 MB or higher.

3. New Hard Disk of 8 GB or higher.

4. Mount the CD-ROM with the NixOS ISO (by clicking on CD/DVD-ROM)

5. Click on Settings / System / Processor and enable PAE/NX

6. Click on Settings / System / Acceleration and enable "VT-x/AMD-V" acceleration

7. Click on Settings / Display / Screen and select VMSVGA as Graphics Controller

8. Save the settings, start the virtual machine, and continue installation like normal

There are a few modifications you should make in configuration.nix. Enable booting:

{
  boot.loader.grub.device = "/dev/sda";
}

Also remove the fsck that runs at startup. It will always fail to run, stopping your boot until you press *.

{
  boot.initrd.checkJournalingFS = false;
}

Shared folders can be given a name and a path in the host system in the VirtualBox settings (Machine / Settings / Shared Folders, then click on the "Add" icon). Add the following to the /etc/nixos/configuration.nix to auto-mount them. If you do not add "nofail", the system will not boot properly.

{ config, pkgs, ...} :
{
  fileSystems."/virtualboxshare" = {
    fsType = "vboxsf";
    device = "nameofthesharedfolder";
    options = [ "rw" "nofail" ];
  };
}

The folder will be available directly under the root directory.