Re: [PATCH v5 0/2] Add config file support for l3fwd

[Bruce Richardson <bruce.richardson@intel.com>]

On Wed, Feb 09, 2022 at 12:00:40PM +0000, Ananyev, Konstantin wrote:
> 
> 
> > > >> Or have a generic library for reading LPM entries.  L3fwd is supposed
> > > >> to be as small as possible (it no longer is), and the real work should
> > > >> be done by libraries to make it easier to build other applications.
> > > >
> > > > I never heard users ask about such thing,
> > > > but if there is a demand for that, then I suppose it could be considered.
> > > > CC-ing LPM/FIB maintainers to comment.
> > > > Though I believe it should be a subject of separate patch and discussion
> > > > (I think many questions will arise - what format should be, how to support
> > > > different types of user-data, to make it generic enough, etc.).
> > >
> > > Agree, it is very application specific, so it could be really difficult
> > > to make it generic.
> >
> > But several other also have LPM tables, so why not have common code for other applications.
> >
> > examples/l3fwd-power/main.c
> > examples/ipsec-secgw/rt.c
> > examples/ip_fragmentation/main.c
> > examples/l3fwd/l3fwd_lpm.c
> > examples/ip_reassembly/main.c
> 
> Ah yes, that's good point.
> All these examples (except ipsec-secgw) started as l3fwd clones,
> so all of them have hard-coded LPM (and EM) tables too.
> Yes it would be good thing to address that problem too,
> and have some common code (and common routes file format) for all of them.
> I don't know is that a good idea to introduce parse file function in LPM/FIB library
> itself, might be better to  have something like examples/common/lpm_parse*.

I think it really depends on whether you are planning on implementing a
general config file for the application, or whether the file(s) will only
contain the LPM/FIB routing entries. If the plan is reading just the
routing entries from file, then I definitely think that it might be
something that would be generally useful inside the library itself.

If it's a more general config file with other app settings in it, then an
examples-only parse function/file would make more sense.

> Anyway, this is an extra effort, and I think no-one has time for it in 22.03 timeframe.
> My suggestion would be for 22.03 go ahead with current l3fwd patches,
> then later we can consider to make it common and update other examples.
> Konstantin