Re: [dpdk-dev] [PATCH 4/4] ethdev: add Tx offload outer L4 checksum definitions

[Jerin Jacob <jerin.jacob@caviumnetworks.com>]

-----Original Message-----
> Date: Mon, 1 Oct 2018 14:45:39 +0100
> From: Ferruh Yigit <ferruh.yigit@intel.com>
> To: Jerin Jacob <jerin.jacob@caviumnetworks.com>, Wenzhuo Lu
>  <wenzhuo.lu@intel.com>, Jingjing Wu <jingjing.wu@intel.com>, Bernard
>  Iremonger <bernard.iremonger@intel.com>, John McNamara
>  <john.mcnamara@intel.com>, Marko Kovacevic <marko.kovacevic@intel.com>,
>  Thomas Monjalon <thomas@monjalon.net>, Andrew Rybchenko
>  <arybchenko@solarflare.com>, Olivier Matz <olivier.matz@6wind.com>
> CC: dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH 4/4] ethdev: add Tx offload outer L4
>  checksum definitions
> User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101
>  Thunderbird/52.9.1
> 
> On 9/13/2018 2:47 PM, Jerin Jacob wrote:
> > Introduced DEV_TX_OFFLOAD_OUTER_UDP_CKSUM, DEV_TX_OFFLOAD_OUTER_TCP_CKSUM
> > and DEV_TX_OFFLOAD_OUTER_SCTP_CKSUM offload flags and
> >
> > PKT_TX_OUTER_L4_NO_CKSUM, PKT_TX_OUTER_TCP_CKSUM, PKT_TX_OUTER_SCTP_CKSUM
> > and PKT_TX_OUTER_UDP_CKSUM mbuf ol_flags to enable Tx outer L4 checksum
> > offload.
> >
> > To use hardware Tx outer L4 checksum offload, the user needs to.
> > # enable following in mbuff:
> > - fill outer_l2_len and outer_l3_len in mbuf
> > - set the flags PKT_TX_OUTER_TCP_CKSUM, PKT_TX_OUTER_SCTP_CKSUM or
> > PKT_TX_OUTER_UDP_CKSUM
> > - set the flag PKT_TX_OUTER_IPV4 or PKT_TX_OUTER_IPV6
> >
> > # configure DEV_TX_OFFLOAD_OUTER_* offload flags in slow path.
> >
> > Signed-off-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
> > ---
> >  app/test-pmd/config.c          | 27 +++++++++++++++++++++++++++
> >  doc/guides/nics/features.rst   |  6 ++++++
> >  lib/librte_ethdev/rte_ethdev.c |  3 +++
> >  lib/librte_ethdev/rte_ethdev.h |  6 ++++++
> >  lib/librte_mbuf/rte_mbuf.c     |  5 +++++
> >  lib/librte_mbuf/rte_mbuf.h     | 23 ++++++++++++++++++++++-
> >  6 files changed, 69 insertions(+), 1 deletion(-)
> >
> > diff --git a/app/test-pmd/config.c b/app/test-pmd/config.c
> > index 92a177e29..85f832bf0 100644
> > --- a/app/test-pmd/config.c
> > +++ b/app/test-pmd/config.c
> > @@ -773,6 +773,33 @@ port_offload_cap_display(portid_t port_id)
> >               else
> >                       printf("off\n");
> >       }
> > +
> > +     if (dev_info.tx_offload_capa & DEV_TX_OFFLOAD_OUTER_UDP_CKSUM) {
> > +             printf("TX Outer UDP checksum:               ");
> > +             if (ports[port_id].dev_conf.txmode.offloads &
> > +                 DEV_TX_OFFLOAD_OUTER_UDP_CKSUM)
> > +                     printf("on\n");
> > +             else
> > +                     printf("off\n");
> > +     }
> > +
> > +     if (dev_info.tx_offload_capa & DEV_TX_OFFLOAD_OUTER_TCP_CKSUM) {
> > +             printf("TX Outer TCP checksum:               ");
> > +             if (ports[port_id].dev_conf.txmode.offloads &
> > +                 DEV_TX_OFFLOAD_OUTER_TCP_CKSUM)
> > +                     printf("on\n");
> > +             else
> > +                     printf("off\n");
> > +     }
> > +
> > +     if (dev_info.tx_offload_capa & DEV_TX_OFFLOAD_OUTER_SCTP_CKSUM) {
> > +             printf("TX Outer SCTP checksum:               ");
> > +             if (ports[port_id].dev_conf.txmode.offloads &
> > +                 DEV_TX_OFFLOAD_OUTER_SCTP_CKSUM)
> > +                     printf("on\n");
> > +             else
> > +                     printf("off\n");
> > +     }
> >  }
> 
> There is also "csum show", "csum set" functions, can you please check that too?

+ Shahaf

I checked the details. It is for "csumonly.c" forward engine to select
various Tx checksum in HW or SW(provide fallback SW implementation) for
testing purpose.

If I need to implement this support for this release, I will reduce the
scope to DEV_TX_OFFLOAD_OUTER_UDP_CKSUM and
DEV_RX_OFFLOAD_OUTER_UDP_CKSUM.

Since there is NO real world non encrypted TCP/SCTP based tunnel
protocols(Based on http://patches.dpdk.org/patch/44692/ discussions)
I will limit the offload definition only to DEV_?X_OFFLOAD_OUTER_UDP_CKSUM and
associated test code in "csumonly.c" forward engine in v2.

Thoughts?

I will split 1/4 and 2/4 as separate patch series and and rework 3/4 and
4/4 as separate series to make forward progress.


> And I am not sure why those functions seems only concerned about Tx csum offloads.

It does check for errors in Rx checksum too. See rx_bad_ip_csum,
rx_bad_l4_csum