int kernctl_get_padded_subbuf_size(int fd, unsigned long *len);
int kernctl_get_subbuf(int fd, unsigned long *len);
int kernctl_get_subbuf_size(int fd, unsigned long *len);
int kernctl_get_padded_subbuf_size(int fd, unsigned long *len);
int kernctl_get_subbuf(int fd, unsigned long *len);
int kernctl_get_subbuf_size(int fd, unsigned long *len);