[PATCH v7 6/8] net/gve: add support for dev info get and dev configure

[Ferruh Yigit]

On 10/24/2022 6:04 AM, Guo, Junfeng wrote:
> 
> 
>> -----Original Message-----
>> From: Ferruh Yigit <ferruh.yigit at amd.com>
>> Sent: Friday, October 21, 2022 17:51
>> To: Guo, Junfeng <junfeng.guo at intel.com>; Zhang, Qi Z
>> <qi.z.zhang at intel.com>; Wu, Jingjing <jingjing.wu at intel.com>;
>> ferruh.yigit at xilinx.com; Xing, Beilei <beilei.xing at intel.com>
>> Cc: dev at dpdk.org; Li, Xiaoyun <xiaoyun.li at intel.com>;
>> awogbemila at google.com; Richardson, Bruce
>> <bruce.richardson at intel.com>; hemant.agrawal at nxp.com;
>> stephen at networkplumber.org; Xia, Chenbo <chenbo.xia at intel.com>;
>> Zhang, Helin <helin.zhang at intel.com>
>> Subject: Re: [PATCH v7 6/8] net/gve: add support for dev info get and dev
>> configure
>>
>> On 10/21/2022 10:19 AM, Junfeng Guo wrote:
>>
>>>
>>> Add dev_ops dev_infos_get.
>>> Complete dev_configure with RX offloads force enabling.
>>>
>>> Signed-off-by: Xiaoyun Li <xiaoyun.li at intel.com>
>>> Signed-off-by: Junfeng Guo <junfeng.guo at intel.com>
>>
>> <...>
>>
>>> --- a/doc/guides/nics/gve.rst
>>> +++ b/doc/guides/nics/gve.rst
>>> @@ -62,6 +62,7 @@ In this release, the GVE PMD provides the basic
>> functionality of packet
>>>    reception and transmission.
>>>    Supported features of the GVE PMD are:
>>>
>>> +- Receiver Side Scaling (RSS)
>>
>> [copy/paste from previous version]
>>
>> I am not sure if driver can claim this, I can see a RSS hash is provided
>> but is it possible to update which hash function to use or update key or
>> RETA table to configure which queue packets goes?
>>
>> Right now what is RSS calculated on?
>>
>> Perpaps RSS support can be documented as limited?
>>
>> And not sure if this update belongs this patch, it should be to the one
>> that has the datapath.
> 
> Looks that the RSS is enabled by default, and there is no RSS init API.
> So I just added back the force-enabled RSS offloading code with the
> corresponding commit message. So the feature list remains unchaged.

There is difference between RSS and RSS hash, what force enabled is "RSS 
hash" where device calculated hash value is shared with application in 
case application wants to reuse this value for some reasons.

But for RSS support, there is a set of configuration required by DPDK 
seems missing, as mentioned above, config RSS hash function (based on 
which part of the packet is the hash calculated), or RETA table update 
so app can select which packets goes to which queue, etc...

Is it at least possible to document what existing configuration is?

Because of missing configuration support, I don't think it is correct to 
document RSS as supported, can you please update it to say something 
like limited support exist with default config.