RMAGIC
op->ov_rmagic = RMAGIC;
*(u_short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC;
ASSERT(op->ov_rmagic == RMAGIC);
ASSERT(*(u_short *)((caddr_t)(op + 1) + op->ov_size) == RMAGIC);
*(u_short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC;