VGE_CRS2
CSR_WRITE_1(sc, VGE_CRS2, VGE_CR2_XON_ENABLE | 0x0B);
CSR_WRITE_1(sc, VGE_CRS2, VGE_CR2_FDX_TXFLOWCTL_ENABLE);
CSR_WRITE_1(sc, VGE_CRS2, VGE_CR2_FDX_RXFLOWCTL_ENABLE);