VMBUS_BR_WAVAIL
VMBUS_BR_WAVAIL(rindex, windex, rbr->rxbr_dsize));
return VMBUS_BR_WAVAIL(rindex, windex, tbr->txbr_dsize);
wavail = VMBUS_BR_WAVAIL(rindex, windex, br->vbr_dsize);
wavail = VMBUS_BR_WAVAIL(rindex, windex, br->vbr_dsize);