From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ajit Khaparde <ajit.khaparde@broadcom.com>
Subject: Re: [PATCH v12 0/6] add Tx preparation
Date: Wed, 30 Nov 2016 13:37:40 -0600
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Cc: dev@dpdk.org, Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>,
 Stephen Hurd <stephen.hurd@broadcom.com>, Jan Medala <jan@semihalf.com>,
 Jakub Palider <jpa@semihalf.com>, John Daley <johndale@cisco.com>,
 Adrien Mazarguil <adrien.mazarguil@6wind.com>,
 Alejandro Lucero <alejandro.lucero@netronome.com>,
 Harish Patil <harish.patil@qlogic.com>,
 Rasesh Mody <rasesh.mody@qlogic.com>,
 Jerin Jacob <jerin.jacob@caviumnetworks.com>,
 Yuanhan Liu <yuanhan.liu@linux.intel.com>, Yong Wang <yongwang@vmware.com>,
 Tomasz Kulasek <tomaszx.kulasek@intel.com>, konstantin.ananyev@intel.com,
 olivier.matz@6wind.com
To: Thomas Monjalon <thomas.monjalon@6wind.com>
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On Mon,
=E2=80=8B=E2=80=8B
Nov 28, 2016 at 5:03 AM, Thomas Monjalon <thomas.monjalon@6wind.com> wrote:

> We need attention of every PMD developers on this thread.
>
> Reminder of what Konstantin suggested:
> "
> - if the PMD supports TX offloads AND
> - if to be able use any of these offloads the upper layer SW would have t=
o:
>     * modify the contents of the packet OR
>     * obey HW specific restrictions
> then it is a PMD developer responsibility to provide tx_prep() that would
> implement
> expected modifications of the packet contents and restriction checks.
> Otherwise, tx_prep() implementation is not required and can be safely set
> to NULL.
> "
>
> I copy/paste also my previous conclusion:
>
> Before txprep, there is only one API: the application must prepare the
> packets checksum itself (get_psd_sum in testpmd).
> With txprep, the application have 2 choices: keep doing the job itself
> or call txprep which calls a PMD-specific function.
> The question is: does non-Intel drivers need a checksum preparation for
> TSO?
> Will it behave well if txprep does nothing in these drivers?
>
> When looking at the code, most of drivers handle the TSO flags.
> But it is hard to know whether they rely on the pseudo checksum or not.
>
> git grep -l 'PKT_TX_UDP_CKSUM\|PKT_TX_TCP_CKSUM\|PKT_TX_TCP_SEG'
> drivers/net/
>
> drivers/net/bnxt/bnxt_txr.c
>
=E2=80=8B::: snip:::
=E2=80=8B


>
> Please, we need a comment for each driver saying
> "it is OK, we do not need any checksum preparation for TSO"
> or
> "yes we have to implement tx_prepare or TSO will not work in this mode"
>

=E2=80=8BThe bnxt devices
 don't need pse
=E2=80=8B=E2=80=8B
udo header checksum in the packet for TSO or TX
checksum offload.
=E2=80=8B So..
=E2=80=8B
"it is OK, we do not need any checksum preparation for TSO"