anchor.diff:      fi
       diskImage="$1"
       if ! test -e "$diskImage"; then
  -      qemu-img create -b ${image}/image -f qcow "$diskImage"
  +      qemu-img create -b ${image}/disk-image.qcow2 -f qcow2 "$diskImage"
       fi
       export TMPDIR=$(mktemp -d)
       export out=/dummy
  
positive.code:     QEMU_OPTS = "-m ${toString (if attrs ? memSize then attrs.memSize else 256)}";
  
      preVM = ''
        diskImage=$(pwd)/image
        origImage=${attrs.diskImage}
        if test -d "$origImage"; then origImage="$origImage/image"; fi
        qemu-img create -b "$origImage" -f qcow $diskImage
  
        echo "$buildCommand" > cmd
  
  
negative.code: 
    createEmptyImage = {size, fullName}: ''
      mkdir $out
      diskImage=$out/disk-image.qcow2
      qemu-img create -f qcow2 $diskImage "${toString size}M"
  
      mkdir $out/nix-support
      echo "${fullName}" > $out/nix-support/full-name
  