Re: [dpdk-dev] [dpdk-dev v2 1/2] ethdev: add new tunnel type for ecpri

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

On 1/7/2021 1:33 PM, Thomas Monjalon wrote:
> 07/01/2021 13:47, Zhang, Qi Z:
>>
>>> -----Original Message-----
>>> From: Thomas Monjalon <thomas@monjalon.net>
>>> Sent: Thursday, January 7, 2021 6:12 PM
>>> To: Guo, Jia <jia.guo@intel.com>
>>> Cc: Zhang, Qi Z <qi.z.zhang@intel.com>; Wu, Jingjing <jingjing.wu@intel.com>;
>>> Yang, Qiming <qiming.yang@intel.com>; Wang, Haiyue
>>> <haiyue.wang@intel.com>; dev@dpdk.org; Yigit, Ferruh
>>> <ferruh.yigit@intel.com>; andrew.rybchenko@oktetlabs.ru; orika@nvidia.com;
>>> getelson@nvidia.com
>>> Subject: Re: [dpdk-dev] [dpdk-dev v2 1/2] ethdev: add new tunnel type for ecpri
>>>
>>> 07/01/2021 10:32, Guo, Jia:
>>>> From: Thomas Monjalon <thomas@monjalon.net>
>>>>> 24/12/2020 07:59, Jeff Guo:
>>>>>> Add type of RTE_TUNNEL_TYPE_ECPRI into the enum of ethdev tunnel
>>>>> type.
>>>>>>
>>>>>> Signed-off-by: Jeff Guo <jia.guo@intel.com>
>>>>>> Reviewed-by: Qi Zhang <qi.z.zhang@intel.com>
>>>>> [...]
>>>>>> --- a/lib/librte_ethdev/rte_ethdev.h
>>>>>> +++ b/lib/librte_ethdev/rte_ethdev.h
>>>>>> @@ -1219,6 +1219,7 @@ enum rte_eth_tunnel_type {
>>>>>>   	RTE_TUNNEL_TYPE_IP_IN_GRE,
>>>>>>   	RTE_L2_TUNNEL_TYPE_E_TAG,
>>>>>>   	RTE_TUNNEL_TYPE_VXLAN_GPE,
>>>>>> +	RTE_TUNNEL_TYPE_ECPRI,
>>>>>>   	RTE_TUNNEL_TYPE_MAX,
>>>>>>   };
>>>>>
>>>>> We tried to remove all these legacy API in DPDK 20.11.
>>>>> Andrew decided to not remove this one because it is not yet
>>>>> completely replaced by rte_flow in all drivers.
>>>>> However, I am against continuing to update this API.
>>>>> The opposite work should be done: migrate to rte_flow.
>>>>
>>>> Agree but seems that the legacy api and driver legacy implementation
>>>> still keep in this release, and there is no a general way to replace
>>>> the legacy by rte_flow right now.
>>>
>>> I think rte_flow is a complete replacement with more features.
>>
>> Thomas, I may not agree with this.
>>
>> Actually the "enum rte_eth_tunnel_type" is used by rte_eth_dev_udp_tunnel_port_add
>> A packet with specific dst udp port will be recognized as a specific tunnel packet type (e.g. vxlan, vxlan-gpe, ecpri...)
>> In Intel NIC, the API actually changes the configuration of the packet parser in HW but not add a filter rule and I guess all other devices may enable it in a similar way.
>> so naturally it should be a device (port) level configuration but not a rte_flow rule for match, encap, decap...
> 
> I don't understand how it helps to identify an UDP port
> if there is no rule for this tunnel.
> What is the usage?
> 
>> So I think it's not a good idea to replace
>> the rte_eth_dev_udp_tunnel_port_add with rte_flow config
>> and also there is no existing rte_flow_action
>> can cover this requirement unless we introduce some new one.
>>
>>> You can match, encap, decap.
>>> There is even a new API to get tunnel infos after decap.
>>> What is missing?
> 
> I still don't see which use case is missing.
> 
> 
>>>>> Sorry, it is a nack.
>>>>> BTW, it is probably breaking the ABI because of RTE_TUNNEL_TYPE_MAX.
>>
>> Yes that may break the ABI but fortunately the checking-abi-compatibility tool shows negative :) , thanks Ferruh' s guide.
>> https://github.com/ferruhy/dpdk/actions/runs/468859673
> 
> That's very strange. An enum value is changed.
> Why it is not flagged by libabigail?
> 

As long as the enum values not sent to the application and kept within the 
library, changing their values shouldn't be problem.

> 
>>>> Oh, the ABI break should be a problem.
>>>>
>>>>> PS: please Cc ethdev maintainers for such patch, thanks.
>>>>> tip: use --cc-cmd devtools/get-maintainer.sh
>>>>
>>>> Thanks for your helpful tip.
> 
> 
>