I would like to add some information about my use case. Many c structs have pointers to arrays of data plus some field indicating the length of those arrays. Sometimes I need to pickle that kind of structs and a bytes object has to somehow be created from each pointer, given the length (the alternative ptr[:len] is too expensive for large arrays). So I need to cast the pointer to a ctypes array first and then convert the array to bytes (sadly, there is no way to pickle a memoryview, so a copy is unavoidable).