Re: [dpdk-dev] [PATCH v3] doc: document NIC features

[Thomas Monjalon <thomas@monjalon.net>]

07/07/2017 16:20, Wiles, Keith:
> 
> > On Jul 7, 2017, at 9:13 AM, Ferruh Yigit <ferruh.yigit@intel.com> wrote:
> > 
> > On 7/7/2017 3:02 PM, Thomas Monjalon wrote:
> >> 07/07/2017 15:57, Ferruh Yigit:
> >>> On 7/7/2017 2:53 PM, Thomas Monjalon wrote:
> >>>> 07/07/2017 15:37, Ferruh Yigit:
> >>>>> On 7/7/2017 11:55 AM, Andrew Rybchenko wrote:
> >>>>>> Also some PMDs have few implementations of the datapath (like vector and 
> >>>>>> usual). Ideally
> >>>>>> we need common way to highlight it. May be it is OK that control path 
> >>>>>> features are duplicated
> >>>>>> in this case, but ideally it should be expressed somehow.
> >>>>> 
> >>>>> I agree different datapath implementations can be documented better, I
> >>>>> just don't know how to do ...
> >>>>> 
> >>>>> For some drivers there are multiple vector implementations and the
> >>>>> feature set for them is not clear. And as you said control features are
> >>>>> duplicated in the table.
> >>>>> 
> >>>>> Perhaps control and datapath features can be separated.
> >>>>> 
> >>>>> Or as Thomas suggested sometime ago, vector and scalar version can be
> >>>>> merged into one in the table and feature can be marked as supported if
> >>>>> both scalar and vector has support for it. But this is not solving
> >>>>> multiple vector implementation problem.
> >>>> 
> >>>> Yes it is the way to go.
> >>>> The features should not be different from a datapath implementation to
> >>>> another one. So they must be merged in only one column.
> >>>> If a feature is not supported in every datapaths of a driver, it should
> >>>> be marked as partially supported... and the developers must implement it.
> >>> 
> >>> But for example for i40e, there are altivec, neon and sse vector
> >>> implementations, how should we document this?
> >> 
> >> They are all only one i40 driver. It should offer the same features
> >> regardless of the platform it runs on.
> >> So it should be only one column in the table.
> > 
> > If one platform does not implements a feature, it will cause feature
> > will be documented as partial independent from other platform's status,
> > this is unfair for the ones implemented it.
> 
> +1
> 
> If a single PMD supports different platforms, then we need to be able to identify these NICs plus show the features.
> Having multiple lines in a table is not difficult and helps identify exactly what is supported on all platforms.

No, you miss the point.
I don't care about the table, it is just a tool to target uniform
implementation. DPDK must be multi-platform. It means an application
relying on a feature must work when changing the CPU.

If a PMD maintainer wants its features advertised as fully supported,
he must reject partial datapath implementation.
It is fair because it is the maintainer's choice.