VIO_TAG_SIZE
#define VIO_VCC_MTU_SIZE (LDC_PACKET_SIZE - VIO_TAG_SIZE)
rv = ldc_write(port->vio.lp, pkt, (VIO_TAG_SIZE + tosend));
rv = ldc_write(port->vio.lp, pkt, (VIO_TAG_SIZE + tosend));
(VIO_TAG_SIZE + tosend), rv);