anchor.diff:        mount -t ext2 /dev/${hd} /fs
       fi
   
  -    mkdir -p /fs/hostfs
  -    
       mkdir -p /fs/dev
       mount -o bind /dev /fs/dev
   
  -    echo "mounting host filesystem..."
  -    mount -t cifs //10.0.2.4/qemu /fs/hostfs -o guest,sec=none
  -
  +    echo "mounting Nix store..."
       mkdir -p /fs/nix/store
  -    mount -o bind /fs/hostfs/nix/store /fs/nix/store
  -    
  +    mount -t cifs //10.0.2.4/store /fs/nix/store -o guest,sec=none
  +
       mkdir -p /fs/tmp
       mount -t tmpfs -o "mode=755" none /fs/tmp
   
  +    echo "mounting host's temporary directory..."
  +    mkdir -p /fs/tmp/xchg
  +    mount -t cifs //10.0.2.4/xchg /fs/tmp/xchg -o guest,sec=none
  +
       mkdir -p /fs/proc
       mount -t proc none /fs/proc
   
  
positive.code:     test -n "$command"
  
      set +e
      chroot /fs $command /tmp $out /hostfs/$tmpDir
      echo $? > /fs/hostfs/$tmpDir/in-vm-exit
  
      mount -o remount,ro dummy /fs
  
  
negative.code:     chmod +x ./run-vm
      source ./run-vm
      
      if ! test -e xchg/in-vm-exit; then
        echo "Virtual machine didn't produce an exit code."
        exit 1
      fi
      
      eval "$postVM"
  
      exit $(cat xchg/in-vm-exit)
    '';
  
  
  