Re: [dpdk-dev] ixgbe and UDP with zero checksum

["Wang, Haiyue" <haiyue.wang@intel.com>]

Hi Paolo,

> -----Original Message-----
> From: Wang, Haiyue
> Sent: Friday, January 29, 2021 10:02
> To: Paolo Valerio <pvalerio@redhat.com>
> Cc: Guo, Jia <jia.guo@intel.com>; Aaron Conole <aconole@redhat.com>; dev@dpdk.org
> Subject: RE: ixgbe and UDP with zero checksum
> 
> > -----Original Message-----
> > From: Paolo Valerio <pvalerio@redhat.com>
> > Sent: Thursday, January 28, 2021 05:35
> > To: Wang, Haiyue <haiyue.wang@intel.com>
> > Cc: Guo, Jia <jia.guo@intel.com>; Aaron Conole <aconole@redhat.com>; dev@dpdk.org
> > Subject: RE: ixgbe and UDP with zero checksum
> >
> > "Wang, Haiyue" <haiyue.wang@intel.com> writes:
> >
> > > Hi Paolo,
> > >
> > >> -----Original Message-----
> > >> From: Paolo Valerio <pvalerio@redhat.com>
> > >> Sent: Wednesday, January 27, 2021 21:50
> > >> To: dev@dpdk.org
> > >> Cc: Guo, Jia <jia.guo@intel.com>; Wang, Haiyue <haiyue.wang@intel.com>; Aaron Conole
> > >> <aconole@redhat.com>
> > >> Subject: ixgbe and UDP with zero checksum
> > >>
> > >> Hi,
> > >>
> > >> performing some tests, I noticed that on ixgbe when receiving UDP
> > >> packets with zero checksum (no checksum) over IPv4, the corresponding
> > >> ol_flag for the l4 checksum is set to PKT_RX_L4_CKSUM_BAD.
> > >>
> > >> In particular, this apparently has an impact on OvS using ct() action
> > >> where UDP packets with zero checksum are not tracked because of that.
> > >
> > >
> > >>
> > >> [1]
> > >>
> >
> https://patchwork.ozlabs.org/project/netdev/patch/20090724040031.30202.1531.stgit@localhost.localdomai
> > >> n/
> > >
> > > About 12 years old patch, it is hardware errata. For fixing this,
> > > have to always disable vector Rx path for 82599, it seems not a
> > > good idea to bring in this workaround. :(
> > >
> >
> > Thanks for the answer.
> > Yes, as I mentioned, the patch is old although still meaningful.
> > I linked it mostly because it mentions the hw errata.
> >
> 
> What's your PCI device ID ? My worked ixgbe:
> 

Sorry, I missed the PKT_RX_L4_CKSUM_BAD information, yes, my NIC have the issue.

> 86:00.0 Ethernet controller [0200]: Intel Corporation 82599ES 10-Gigabit SFI/SFP+ Network Connection
> [8086:10fb] (rev 01)
> 
> I'm wondering if people will complain that the patch will mark the real bad checksum UDP as

Zero checksum is more popular case, please file a bug on https://bugs.dpdk.org/ to trace the fix.

Thanks for pointing it out.

> GOOD. For handling this correctly, looks like driver needs to check the UDP's checksum value,
> if zero, then skip the error information, but this makes driver do the network stack things ...
> 
>