08/02/2021 07:29, Chengchang Tang:
Hi, Thomas Monjalon and Ferruh Yigit and others.
I have some questions about 'rte_eth_tx_prepare'.
When I use TSO offload in bond mode, the checksum error occurs. It is because the bond PMD does not implement 'tx_prepare'. So, it will not invoke the 'tx_prepare' of each PMDs to do prepare for the PMDs. I am not sure whether to add the 'tx_preapre' implementation for the bond PMD or put the process of pseudo header in the apps.
And we are now designing the outer UDP cksum offload for HNS3 PMD. I find that many PMDs process these pseudo headers in 'tx_prepare', but does not process the pseudo header for outer UDP checksum offload. Instead, it is processed in csum forward mode of testpmd. Does this mean that the pseudo header should be completed by the apps and the apps does not need to call 'tx_prepare' to avoid repeated processing? (it seems not transplantable) If so, it seems that PMDs need to avoid doing this in 'tx_prepare'.
Here are two questions:
- What functions should be included in the 'tx_prepare' for PMDs?
- Whether an app must invoke 'rte_eth_tx_prepare' or under which
conditions an app must invoke the 'rte_eth_tx_prepare'?
I would say by default the app should prepare the checksums, except if there is an explicit offload request (DEV_TX_OFFLOAD_*). I think the tx_prepare should only prepare the HW Tx offload if the offload is not entirely done in HW.