NRXDESC
struct rdesc rxd[NRXDESC];
uint8_t rxstore[NRXDESC][FRAMESIZE];
for (i = 0; i < NRXDESC; i++) {
CSR_WRITE_2(l, VR_RDCSIZE, NRXDESC - 1);
CSR_WRITE_2(l, VR_RBRDU, NRXDESC - 1);
wbinv(rxd, NRXDESC * sizeof(struct rdesc));
l->rx = (l->rx + 1) & (NRXDESC - 1);