man hsh:

	--mountpoints=LIST
		Defines  list  of  known  mount  points.   Every  build
		dependence which belongs to  this list will be mounted.
		If  some  mount  point  is not  explicitly  allowed  in
		hasher-priv.conf(5),       build       will       fail.
		($known_mountpoints);

	--mountpoints=\,LIST\/
		comma-separated    list   of    known   mount    points
		($known_mountpoints);