anchor.diff:  
   
     qemuCommandLinux = ''
  -    qemu-system-x86_64 -no-kvm-irqchip \
  +    qemu-system-x86_64 \
         -nographic -no-reboot \
  -      -net nic,model=virtio -net user -smb / \
  -      -drive file=$diskImage,if=virtio,boot=on \
  +      -net nic,model=virtio -chardev socket,id=samba,path=$TMPDIR/samba -net user,guestfwd=tcp:10.0.2.4:139-chardev:samba \
  +      -drive file=$diskImage,if=virtio,boot=on,cache=writeback,werror=report \
         -kernel ${kernel}/bzImage \
         -initrd ${initrd}/initrd \
         -append "console=ttyS0 panic=1 command=${stage2Init} tmpDir=$TMPDIR out=$out mountDisk=$mountDisk" \
  
positive.code:   vmRunCommand = qemuCommand: writeText "vm-run" ''
      export > saved-env
  
      PATH=${coreutils}/bin:${kvm}/bin:${samba}/sbin
  
      diskImage=''${diskImage:-/dev/null}
  
      eval "$preVM"
  
      # Write the command to start the VM to a file so that the user can
      # debug inside the VM if the build fails (when Nix is called with
  
negative.code: 
    createRootFS = ''
      mkdir /mnt
      ${e2fsprogs}/sbin/mke2fs -F /dev/${hd}
      ${utillinux}/bin/mount -t ext2 /dev/${hd} /mnt
  
      if test -e /mnt/.debug; then
        exec ${bash}/bin/sh
  