__siov
struct __siov iov;
struct __siov iov;
struct __siov *iov;
struct __siov *uio_iov;
struct __siov iov;
struct __siov iov[NIOV];/* ... and individual io vectors */
struct __siov iov[2];
struct __siov iov;
struct __siov *iov;
struct __siov iov;
struct __siov iov[NIOV];
struct __siov *iovp;