Re: [dpdk-dev] [PATCH 2/2] eal: add eal_parse_optionlist to parse user input

["Govindharajan, Hariprasad" <hariprasad.govindharajan@intel.com>]

Hi,
I am planning to move the existing parser function to the testpmd file instead of keeping it in the eal and will revert the eal back.

Also, I am planning to create an util file in eal with this parser and do a RFC.

@Stephen Hemminger, We already investigated the existing function and then decided to re-use it as seen in the patch. For creating an API, is there any other specific requirements 
that should be addressed? Please clarify us.

Thanks
G Hariprasad

-----Original Message-----
From: Stephen Hemminger <stephen@networkplumber.org> 
Sent: Wednesday, January 29, 2020 7:20 PM
To: Yigit, Ferruh <ferruh.yigit@intel.com>
Cc: David Marchand <david.marchand@redhat.com>; Thomas Monjalon <thomas@monjalon.net>; Govindharajan, Hariprasad <hariprasad.govindharajan@intel.com>; dev <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH 2/2] eal: add eal_parse_optionlist to parse user input

On Wed, 29 Jan 2020 18:07:05 +0000
Ferruh Yigit <ferruh.yigit@intel.com> wrote:

> On 1/29/2020 5:44 PM, David Marchand wrote:
> > On Tue, Jan 28, 2020 at 6:35 PM Ferruh Yigit <ferruh.yigit@intel.com> wrote:  
> >> On 1/27/2020 10:30 AM, Hariprasad Govindharajan wrote:  
> >>> In current version, there is a function which parses the corelist 
> >>> based on user value. A new generic function eal_parse_optionlist 
> >>> is added which will parse corelist as well as similar user input 
> >>> so that we can use it as a public API too.
> >>>
> >>> Signed-off-by: Hariprasad Govindharajan 
> >>> <hariprasad.govindharajan@intel.com>
> >>
> >> Hi David,
> >>
> >> Overall this patchset is to add '--portlist' command to testpmd and 
> >> remove existing 64 port limitation.
> >>
> >> And in this patch re-uses the exiting parser function in eal and 
> >> converts it to API, question is if eal is good place to have this API, what do you think about it?
> > 
> > Exporting string parsers from the EAL has little value.
> > Ok we avoid code duplication (and I can see other places in the tree 
> > where it might be used), but in the end we will have to maintain 
> > this API in the ABI when it enters the stable ABI.
> > 
> > I am for avoiding this.
> > 
> >  
> 
> The same function can be used in some sample applications too (which 
> are using port mask), so instead of duplicating it multiple times, it 
> would be nice to have this function somewhere that applications can use.
> 
> Does it makes sense to have a rte_util.c (under in eal or as a 
> separate library) to have this kind of application helper functions?

It makes sense to have a rte library that handles arbitrary size bitvector and has string handling functions. Kind of like what kernel has for the cpuset parsing.  This could be used for cpus in EAL and port-masks or other arrays in applications.

But just doing copy/paste of existing code without thinking about how API should work is a bad idea.