[dpdk-dev] UDP Checksum
Ananyev, Konstantin
konstantin.ananyev at intel.com
Thu Nov 6 18:07:57 CET 2014
> -----Original Message-----
> From: Ananyev, Konstantin
> Sent: Thursday, November 06, 2014 5:04 PM
> To: Ananyev, Konstantin
> Subject: FW: [dpdk-dev] UDP Checksum
>
>
>
> From: Alex Markuze [mailto:alex at weka.io]
> Sent: Thursday, November 06, 2014 4:27 PM
> To: Ananyev, Konstantin
> Cc: dev at dpdk.org
> Subject: Re: [dpdk-dev] UDP Checksum
>
> I was setting both ip and udp scum fields to 0. PKT_TX_UDP_CKSUM == PKT_TX_L4_MASK = 0x6000.
>
> I was not aware of the get_ipv4_psd_sum(ipv4_hdr);
> And I'm quite frankly surprised the HW doesn't already do this. Farther more I don't remember kernel drivers messing with
> L3 Headers(bnx2x/mlx4). Is this true for all PMDs that do scum offloads?
I suppose it depends on HW implementation.
All Intel NICs I am aware about (e1000, ixgbe, i40e) expect that SW provides the pseudo IP header checksum in the L4 header.
Not sure what is the story with NICs from other manufactures.
>
> I will give it a try now.
>
>
> On Thu, Nov 6, 2014 at 6:15 PM, Ananyev, Konstantin <konstantin.ananyev at intel.com> wrote:
>
>
> > -----Original Message-----
> > From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Alex Markuze
> > Sent: Thursday, November 06, 2014 4:05 PM
> > To: dev at dpdk.org
> > Subject: [dpdk-dev] UDP Checksum
> >
> > Hi,
> > I'm seeing "UDP: bad checksum." messages(dmesg) for packets sent by my dpdk
> > app to a socket on a remote machine.
> > Looking at the packets the scum value is set, its just not what wireshark
> > expects.
> >
> > When sending I'm setting these fields in the egress packets.
> >
> > pkt->pkt.vlan_macip.f.l2_len = sizeof(struct ether_hdr);
> >
> > pkt->pkt.vlan_macip.f.l3_len = sizeof(struct ipv4_hdr);
> >
> > pkt->ol_flags |= (PKT_TX_IP_CKSUM | PKT_TX_L4_MASK);
> > //PKT_TX_OFFLOAD_MASK;
> >
> >
> > I'm working with a 82599 VF.
> >
> >
> > Any thoughts? I'm not sure what else to check.
> As I remember, you have to setup IPV4 header checksum to 0 and
> calculate and setup pseudo-header checksum for UDP.
> From app/test-pmd/csumonly.c:
> ...
> if (pkt_ol_flags & (PKT_RX_IPV4_HDR | PKT_RX_TUNNEL_IPV4_HDR)) {
>
> /* Do not support ipv4 option field */
> l3_len = sizeof(struct ipv4_hdr) ;
>
> ...
>
> /* Do not delete, this is required by HW*/
> ipv4_hdr->hdr_checksum = 0;
>
> ...
>
> if (l4_proto == IPPROTO_UDP) {
> udp_hdr = (struct udp_hdr*) (rte_pktmbuf_mtod(mb,
> unsigned char *) + l2_len + l3_len);
> if (tx_ol_flags & 0x2) {
> /* HW Offload */
> ol_flags |= PKT_TX_UDP_CKSUM;
> if (ipv4_tunnel)
> udp_hdr->dgram_cksum = 0;
> else
> /* Pseudo header sum need be set properly */
> udp_hdr->dgram_cksum =
> get_ipv4_psd_sum(ipv4_hdr);
>
>
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