sesasync
static void sesasync(void *, u_int32_t, struct cam_path *, void *);
status = xpt_register_async(AC_FOUND_DEVICE, sesasync, NULL, NULL);
xpt_register_async(0, sesasync, periph, periph->path);
cgd->ccb_h.path, sesasync, AC_FOUND_DEVICE, cgd);
xpt_register_async(AC_LOST_DEVICE, sesasync, periph, periph->path);