fd.iovecs = new([]syscall.Iovec)
		}
		*fd.iovecs = iovecs // cache

		var wrote uintptr
		wrote, err = writev(fd.Sysfd, iovecs)
		if wrote == ^uintptr(0) {
			wrote = 0
		}
		TestHookDidWritev(int(wrote))
		n += int64(wrote)
		consume(v, int64(wrote))
		clear(iovecs)
		if err != nil {
			if err == syscall.EINTR {
				continue
			}
			if err == syscall.EAGAIN {