[dpdk-dev] [RFC PATCH 4/4] ethdev: add helpers to move to the new offloads API

[Ferruh Yigit]

On 8/30/2017 7:30 AM, Shahaf Shuler wrote:
> Tuesday, August 29, 2017 3:55 PM, Ferruh Yigit:
>>>> Considering the re-configuration is risky, and without other ideas I will
>> need to fall back to the error flow case.
>>>> Are we OK with that?
>>>
>>> I think we can take the risk of keeping this call to
>>> rte_eth_dev_configure() in the middle of rte_eth_rx_queue_setup().
>>> In theory it should be acceptable.
>>> If we merge it soon, it can be better tested with every drivers.
>>
>> I doubt about taking that risk. Some driver does HW configuration via
>> configure() and combination of start/stop, setup_queue and configure can
>> be complex.
>>
>> I am for generating error for this case.
>>
>> Generating error also can be good motivation for PMDs to adapt new
>> method.
> 
> Adding Ananyev suggestion from other thread:
> For tx_prepare() work, we used the following approach:
> 1. submitted patch with changes in rte_ethdev and PMDs we  are familiar with (Intel ones).
>     For other PMDs - patch contained just minimal changes to make it build cleanly.
> 2. Asked other PMD maintainers to review rte_ethdev changes and provide a proper patch
>     for the PMD they own.

tx_prepare() is a little different, since it was not clear if all PMDs
needs updating that is why asked to PMD owners, and the ones requires
updating already has been updated with ethdev patch. Here we know all
PMDs need updating, and they need proper time in advance.

> 
> So I am OK with both suggestions. Meaning:
> 1. Define the case were application use the new offloads API with PMD which supports the old one as an error.
> 2. apply patches to ethdev with the above behavior.
> 
> Just to emphasize, it means that PMDs which won't move to the new API by the end of 17.11 will not be able to run with any of the examples and application on DPDK tree (and also with other applications which moved to the new API), as I plan to submit patches which convert them all to the new API.

I think it is good idea to update samples/apps to new method, but this
can be short notice for PMD owners.

Can we wait one more release to update samples/apps, to give time for
PMDs to be updated, since old applications will work with new PMDs
(thanks to your helpers), I believe this won't be a problem.

> 
> Any objection to this approach? 
> 
>