anchor.diff:      ifconfig lo up
       ifconfig eth0 up 192.168.0.2
   
  -    mkdir -p /xchg /nix/store /etc /var/run /var/log
  -
  -    cat > /etc/passwd <<PASSWD
  +    mount -t tmpfs none /fs
  +    mkdir -p /fs/nix/store /fs/xchg /fs/dev /fs/sys /fs/proc /fs/etc /fs/tmp
  +
  +    mount -o bind /dev /fs/dev
  +    mount -t sysfs none /fs/sys
  +    mount -t proc none /fs/proc
  +
  +    mount -t 9p \
  +      -o trans=virtio,version=9p2000.L,msize=262144,cache=loose \
  +      store /fs/nix/store
  +
  +    mount -t 9p \
  +      -o trans=virtio,version=9p2000.L,msize=262144,cache=loose \
  +      xchg /fs/xchg
  +
  +    cat > /fs/etc/passwd <<PASSWD
       root:x:0:0::/root:/bin/false
       nobody:x:65534:65534::/var/empty:/bin/false
       PASSWD
   
  -    mount -t 9p \
  -      -o trans=virtio,version=9p2000.L,msize=262144,cache=loose \
  -      xchg /xchg
  -
  -    mount -t 9p \
  -      -o trans=virtio,version=9p2000.L,msize=262144,cache=loose \
  -      store /nix/store
  -
  -    exec "$command"
  +    set +e
  +    chroot /fs $command $out
  +    echo $? > /fs/xchg/in-vm-exit
  +
  +    poweroff -f
     '';
   
     initrd = makeInitrd {
  
positive.code:     # Loop forever, because this VM is going to be killed.
      ${loopForever}
    '' else ''
      ${coreutils}/bin/mkdir -p /etc/samba /etc/samba/private /var/lib/samba
      ${coreutils}/bin/cat > /etc/samba/smb.conf <<CONFIG
      [global]
      security = user
  
negative.code:     ${coreutils}/bin/touch /xchg/suspend_now
      ${loopForever}
      ''}
    ''));
  
    kernelAppend = lib.concatStringsSep " " [
  