Re: [dpdk-dev] [PATCH] ethdev: fix applications failure on configure

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 5/2/2018 6:09 PM, Shahaf Shuler wrote:
> Wednesday, May 2, 2018 1:06 PM, Thomas Monjalon:
>> Subject: Re: [dpdk-dev] [PATCH] ethdev: fix applications failure on configure
>>
>> 02/05/2018 11:58, Xueming(Steven) Li:
>>> From: Ferruh Yigit <ferruh.yigit@intel.com>
>>>> Or as Xueming suggested, we can take rss_hf config as best effort and
>> not return error at all.
>>>>
>>>> I think this forces PMDs to have up-to-date flow_type_rss_offloads
>> values, is there any other benefit?
>>>> What was the initial motivation to add error return on this check?
>>>
>>> The original idea is to add rss_hf check on mlx5 PMD, while it looks
>>> more generic to move the check to ethdev api from discussion[1].
>>>
>>> [1]
>>>
>> https://emea01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fww
>> w.
>>> dpdk.org%2Fml%2Farchives%2Fdev%2F2018-
>> April%2F095136.html&data=02%7C01
>>>
>> %7Cshahafs%40mellanox.com%7Cc773c15dcbda49d21da008d5b0145864%7C
>> a652971
>>>
>> c7d2e4d9ba6a4d149256f461b%7C0%7C0%7C636608523825745897&sdata=jDU
>> OyU0E%
>>> 2FY5g3oSKBQxUsz8Ehr%2FN3ek5h8kotQBLZBU%3D&reserved=0
>>
>> I think it is not correct to not return an error when the app request an offload
>> which is not supported.
>>
>> Do we agree to work on PMDs and applications to fix this offload
>> compliance?
>> And submit a deprecation notice to return an error in a later release?
> 
> I probably missed it but why deprecation notice is required? 
> Per my understanding it is just a fix to enforce better the API which is:
> 1. application reads capabilities 
> 2. application sets offloads accordingly. 

The return error on some values is new, and this is a behavior change in API.

Some applications working fine will start throwing error, and for DPDK
application developers this may mean go and update their application.

For possible application update I believe the change should be announced in
deprecation notice in advance.