Re: [RFC] New CLI for DPDK

[Thomas Monjalon <thomas.monjalon@6wind.com>]

2017-03-24 14:48, Wiles, Keith:
> 
> > On Mar 24, 2017, at 8:09 AM, Olivier Matz <olivier.matz@6wind.com> wrote:
> > 
> > Hi Keith,
> > 
> > On Thu, 23 Mar 2017 16:13:21 +0000, "Wiles, Keith" <keith.wiles@intel.com> wrote:
> >>> On Mar 10, 2017, at 9:25 AM, Wiles, Keith <keith.wiles@intel.com> wrote:
> >>> 
> >>> I would like to request for comments on a new CLI design and get any feedback. I have attached the cli.rst text, which is still a work in progress for you review.
> >>> 
> >>> I have also ported the CLI to a version of Pktgen on the ‘dev’ branch of the repo in DPDK.org.
> >>> 
> >>> http://dpdk.org/browse/apps/pktgen-dpdk/refs/?h=dev
> >>> 
> >>> I would like to submit the CLI library to be used in DPDK, if that seems reasonable to everyone. I need more testing of the API and Pktgen, but I feel it has a simpler design, easier to understand and hopefully make it easier for developers to add commands.
> >>> 
> >>> As an example I quickly converted over testpmd from CMDLINE to CLI (I just add a -I option to select CLI instead) and reduced the test-pmd/cmdline.c file from 12.6K lines to about 4.5K lines. I did not fully test the code, but the ones I did test seem to work.
> >>> 
> >>> I do not expect DPDK to convert to the new CLI only if it makes sense and I am not suggesting to replace CMDLINE library.
> >>> 
> >>> If you play with the new CLI in pktgen and see any problems or want to suggest new features or changes please let me know.
> >>> 
> >>> Comments on the cli.rst text is also welcome, but the cli.rst is not complete. I think this file needs to be broken into two one to explain the example and another to explain CLI internals.  
> >> 
> >> Any more comments on the CLI code for DPDK.
> >> 
> >> Should I submit a patch for DPDK or would it be better to push this into its own repo on DPDK?
> >> 
> > 
> > I agree that there is a large possibility of improvements in librte_cmdline.
> > 
> > Just for reference, I think this design was not that bad at the time it
> > was introduced:
> > - declaring commands as static variables makes sense when running on
> >  baremetal without malloc library
> > - implementing a readline-like part was also needed because not available
> >  on baremetal
> > - masking structures to the user was harder due to the lack of malloc
> > - having a cli is really helpful for a program like testpmd (both for
> >  a user or for an automatic test program)
> 
> I agree, but we do need to use a better version.
> 
> > 
> > Few efforts were made to enhance this library because it's not the heart
> > of dpdk.
> 
> True CLI is not the heart of DPDK, but adding a better supported CLI could be a reasonable addition to DPDK for developers to create a real produce instead of cmdline, which is stated was not a CLI for a real product.

We can ask to the techboard whether CLI is in DPDK scope.
My position: it is neither in the scope of the repo nor in the scope of dpdk.org.

> > The current status is acceptable to me: this library is mostly used
> > internally in dpdk for test apps, and application developers are free
> > to use a better one if they want.
> > 
> > But adding another cli lib in dpdk does not make sense to me. I think
> > the proper direction would be to remove the cli from dpdk and use a
> > good cli library that is available in distros. But for that:
> > - we need to find one
> > - we need to update all examples/tests that use the cmdline, and
> >  that will be a lot of work
> > - we need to enhance dpdk framework to better manage deps with
> >  external libraries

I agree we could convert testpmd and examples to a new CLI lib.
Then we could remove librte_cmdline from DPDK.

> Replacing applications with a new CLI is background work and we do not need to toss out cmdline until all have been converted, which could take a while. We can move cmdline out of DPDK, but the problem is most of the current applications require cmdline and the developer would be required to pull DPDK and cmdline. I would suggest we have both in DPDK and slowly convert the apps to use the new CLI.
> 
> If we split up DPDK repo into smaller repos and use something like the ‘repo’ command with a catalog file then it would be mostly transparent to the developer we have multiple repos. Until that day it does seem more reasonable to have CLI in DPDK repo, but I am willing to have it in a different repo for now.

It is reasonnable for an application to have some dependencies.
It is commonly managed in three ways:
- detect the lib on the system
- download the lib as part of the build process
- ask user to download it

> > So, in my opinion, the CLI you are proposing should be hosted on another
> > repo.
> 
> I will contact Thomas to setup a new repo for the CLI.

We had a private discussion.
I have tried to put here my conclusions.