Re: [dpdk-dev] [PATCH v2 1/4] ethdev: add Rx offload outer UDP checksum definition

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

-----Original Message-----
> Date: Mon, 08 Oct 2018 11:04:51 +0200
> From: Thomas Monjalon <thomas@monjalon.net>
> To: Jerin Jacob <jerin.jacob@caviumnetworks.com>, Ferruh Yigit
>  <ferruh.yigit@intel.com>, "Ananyev, Konstantin"
>  <konstantin.ananyev@intel.com>
> Cc: Andrew Rybchenko <arybchenko@solarflare.com>, "Lu, Wenzhuo"
>  <wenzhuo.lu@intel.com>, "Wu, Jingjing" <jingjing.wu@intel.com>,
>  "Iremonger, Bernard" <bernard.iremonger@intel.com>, "Mcnamara, John"
>  <john.mcnamara@intel.com>, "Kovacevic, Marko" <marko.kovacevic@intel.com>,
>  Olivier Matz <olivier.matz@6wind.com>, "dev@dpdk.org" <dev@dpdk.org>,
>  "shahafs@mellanox.com" <shahafs@mellanox.com>, "didier.pallard@6wind.com"
>  <didier.pallard@6wind.com>
> Subject: Re: [dpdk-dev] [PATCH v2 1/4] ethdev: add Rx offload outer UDP
>  checksum definition
> 
> 08/10/2018 10:24, Jerin Jacob:
> > From: Ferruh Yigit <ferruh.yigit@intel.com>
> > > On 10/6/2018 1:18 PM, Ananyev, Konstantin wrote:
> > > > From: Jerin Jacob [mailto:jerin.jacob@caviumnetworks.com]
> > > >> From: Thomas Monjalon <thomas@monjalon.net>
> > > >>> However, we should re-visit the flag PKT_RX_EIP_CKSUM_BAD.
> > > >>
> > > >> Do we need to block this patch due to the exiting PKT_RX_EIP_CKSUM_BAD
> > > >> definition?
> > > >>
> > > >> I already added the author of the PKT_RX_EIP_CKSUM_BAD flag and ethdev and mbuf
> > > >> maintainers in this list. So what else I need make forward progress
> > > >> on this patch?
> > > >>
> > > >> I think, the definition of PKT_RX_EIP_CKSUM_BAD based on HW capability. It
> > > >> is safe to assume that ALL HW can support CKSUM BAD if the feature is
> > > >> available and hence it is more portable.
> > > >
> > > > Yes, as I remember PKT_RX_EIP_CKSUM_BAD is based on DEV_RX_OFFLOAD_OUTER_IPV4_CKSUM.
> > >
> > > Switching to two bit won't reduce the portability, HW supports only reporting
> > > CKSUM_BAD can set BAD || UNKNOWN.
> >
> > UNKNOWN is not a bit. It is represented as 0. It spec has 2 bit, then
> > driver need to report GOOD as well.
> >
> > Same applies for PKT_RX_EL4_CKSUM as well.
> >
> > >
> > > And I think patch is not blocked by PKT_RX_EIP_CKSUM_BAD, it can be changed
> > > separately, for this patch question is can we represent PKT_RX_EL4_CKSUM_* with
> > > two bits, to have BAD/GOOD/UNKNOWN?
> 
> Yes, exact.
> 
> PKT_RX_EIP_CKSUM_BAD must be left aside.
> We should just avoid taking it as a reference.
> And we can reconsider its definition later.

OK.

IMO, Using 2 bit scheme for tunneled checksum has following performance
issue from driver side.

Driver need to mark the packet as GOOD. All the HW can support
detection of BAD. That not necessary mean GOOD in case of tunnel packet,
so driver has to detect the packet is tunneled and packet is not BAD
then mark GOOD.



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