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

[Harish Patil]

>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.
>
>git grep -l 'PKT_TX_UDP_CKSUM\|PKT_TX_TCP_CKSUM\|PKT_TX_TCP_SEG'
>drivers/net/
>
>drivers/net/bnxt/bnxt_txr.c
>drivers/net/cxgbe/sge.c
>drivers/net/e1000/em_rxtx.c
>drivers/net/e1000/igb_rxtx.c
>drivers/net/ena/ena_ethdev.c
>drivers/net/enic/enic_rxtx.c
>drivers/net/fm10k/fm10k_rxtx.c
>drivers/net/i40e/i40e_rxtx.c
>drivers/net/ixgbe/ixgbe_rxtx.c
>drivers/net/mlx4/mlx4.c
>drivers/net/mlx5/mlx5_rxtx.c
>drivers/net/nfp/nfp_net.c
>drivers/net/qede/qede_rxtx.c
>drivers/net/thunderx/nicvf_rxtx.c
>drivers/net/virtio/virtio_rxtx.c
>drivers/net/vmxnet3/vmxnet3_rxtx.c
>
>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"
>

qede PMD doesn’t currently support TSO yet, it only supports Tx TCP/UDP/IP
csum offloads.
So Tx preparation isn’t applicable. So as of now -
"it is OK, we do not need any checksum preparation for TSO"


Thanks,
Harish