On 10/12/2017 10:24 AM, Roger B Melton wrote:
> When copying VLAN tags from the RX descriptor to the vlan_tci field
> in the mbuf header, igb_rxtx.c:eth_igb_recv_pkts() and
> eth_igb_recv_scattered_pkts() both assume that the VLAN tag is always
> little endian. While i350, i354 and /i350vf VLAN non-loopback
> packets are stored little endian, VLAN tags in loopback packets for
> those devices are big endian.
>
> For i350, i354 and i350vf VLAN loopback packets, swap the tag when
> copying from the RX descriptor to the mbuf header. This will ensure
> that the mbuf vlan_tci is always little endian.
>
> Signed-off-by: Roger B Melton <rmel...@cisco.com>
<...>
> @@ -946,9 +954,16 @@ eth_igb_recv_pkts(void *rx_queue, struct rte_mbuf
> **rx_pkts,
>
> rxm->hash.rss = rxd.wb.lower.hi_dword.rss;
> hlen_type_rss = rte_le_to_cpu_32(rxd.wb.lower.lo_dword.data);
> - /* Only valid if PKT_RX_VLAN_PKT set in pkt_flags */
> - rxm->vlan_tci = rte_le_to_cpu_16(rxd.wb.upper.vlan);
> -
> + /*
> + * The vlan_tci field is only valid when PKT_RX_VLAN_PKT is
> + * set in the pkt_flags field and must be in CPU byte order.
> + */
> + if ((staterr & rte_cpu_to_le_32(E1000_RXDEXT_STATERR_LB)) &&
> + (rxq->flags & IGB_RXQ_FLAG_LB_BSWAP_VLAN)) {
This is adding more condition checks into Rx path.
What is the performance cost of this addition?
> + rxm->vlan_tci = rte_be_to_cpu_16(rxd.wb.upper.vlan);
> + } else {
> + rxm->vlan_tci = rte_le_to_cpu_16(rxd.wb.upper.vlan);
> + }
> pkt_flags = rx_desc_hlen_type_rss_to_pkt_flags(rxq,
> hlen_type_rss);
> pkt_flags = pkt_flags | rx_desc_status_to_pkt_flags(staterr);
> pkt_flags = pkt_flags | rx_desc_error_to_pkt_flags(staterr);
<...>
