[dpdk-dev] [PATCH v12 0/6] add Tx preparation

Ajit Khaparde ajit.khaparde at broadcom.com
Wed Nov 30 20:37:40 CET 2016

On Mon,
Nov 28, 2016 at 5:03 AM, Thomas Monjalon <thomas.monjalon at 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 to:
>     * 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.
> drivers/net/
> drivers/net/bnxt/bnxt_txr.c
​::: snip:::

> 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"

​The bnxt devices
 don't need pse
udo header checksum in the packet for TSO or TX
checksum offload.
​ So..
"it is OK, we do not need any checksum preparation for TSO"

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