vgen_sendmsg_shm
rv = vgen_sendmsg_shm(ldcp, (caddr_t)tagp, sizeof (dringmsg));
rv = vgen_sendmsg_shm(ldcp, (caddr_t)tagp, sizeof (*msgp));
static int vgen_sendmsg_shm(vgen_ldc_t *ldcp, caddr_t msg, size_t msglen);