[dpdk-dev] [EXT] Re: Re: [PATCH] devtools: skip the symbol check when map file under drivers

Jerin Jacob Kollanukkaran jerinj at marvell.com
Wed May 22 18:22:53 CEST 2019


> -----Original Message-----
> From: Neil Horman <nhorman at tuxdriver.com>
> Sent: Wednesday, May 22, 2019 9:09 PM
> To: Jerin Jacob Kollanukkaran <jerinj at marvell.com>
> Cc: Bruce Richardson <bruce.richardson at intel.com>; dev at dpdk.org;
> thomas at monjalon.net; stable at dpdk.org
> Subject: Re: [EXT] Re: [dpdk-dev] Re: [PATCH] devtools: skip the symbol
> check when map file under drivers
> 
> On Wed, May 22, 2019 at 02:25:14PM +0000, Jerin Jacob Kollanukkaran wrote:
> > > -----Original Message-----
> > > From: Neil Horman <nhorman at tuxdriver.com>
> > > Sent: Wednesday, May 22, 2019 7:41 PM
> > > To: Jerin Jacob Kollanukkaran <jerinj at marvell.com>
> > > Cc: Bruce Richardson <bruce.richardson at intel.com>; dev at dpdk.org;
> > > thomas at monjalon.net; stable at dpdk.org
> > > Subject: [EXT] Re: [dpdk-dev] Re: [PATCH] devtools: skip the symbol
> > > check when map file under drivers
> > >
> > > External Email
> > >
> > > --------------------------------------------------------------------
> > > -- On Wed, May 22, 2019 at 01:41:03PM +0000, Jerin Jacob
> > > Kollanukkaran wrote:
> > > > > -----Original Message-----
> > > > > From: Neil Horman <nhorman at tuxdriver.com>
> > > > > Sent: Wednesday, May 22, 2019 6:43 PM
> > > > > To: Jerin Jacob Kollanukkaran <jerinj at marvell.com>
> > > > > Cc: Bruce Richardson <bruce.richardson at intel.com>; dev at dpdk.org;
> > > > > thomas at monjalon.net; stable at dpdk.org
> > > > > Subject: [EXT] Re: [dpdk-dev] Re: [PATCH] devtools: skip the
> > > > > symbol check when map file under drivers
> > > > >
> > > > > External Email
> > > > >
> > > > > ----------------------------------------------------------------
> > > > > ----
> > > > > -- On Wed, May 22, 2019 at 11:54:13AM +0000, Jerin Jacob
> > > > > Kollanukkaran
> > > > > wrote:
> > > > > > > -----Original Message-----
> > > > > > > From: Bruce Richardson <bruce.richardson at intel.com>
> > > > > > > Sent: Wednesday, May 22, 2019 4:21 PM
> > > > > > > To: Jerin Jacob Kollanukkaran <jerinj at marvell.com>
> > > > > > > Cc: Neil Horman <nhorman at tuxdriver.com>; dev at dpdk.org;
> > > > > > > thomas at monjalon.net; stable at dpdk.org
> > > > > > > Subject: Re: [dpdk-dev] [EXT] Re: [PATCH] devtools: skip the
> > > > > > > symbol check when map file under drivers
> > > > > > >
> > > > > > > > > Sorry, but I'm not ok with this, because many of our
> > > > > > > > > DPDK PMDs have functions that get exported which are
> > > > > > > > > meant to be called by applications directly.  The
> > > > > > > >
> > > > > > > > OK. Just to update my knowledge, Should those API needs to
> > > > > > > > go through ABI/API depreciation process?
> > > > > > > >
> > > > > > > > Actually, I am concerned about the APIs, which is called
> > > > > > > > between drviers not the application. For example,
> > > > > > > > drivers/common/dpaax/rte_common_dpaax_version.map
> > > > > > > >
> > > > > > > > it is not interface to application rather it is for intra driver case.
> > > > > > > > I think, I can change my logic to Skip the symbols which
> > > > > > > > NOT starting with
> > > > > > > rte_.
> > > > > > > > Agree?
> > > > > > > >
> > > > > > > > Context:
> > > > > > > > I am adding a new driver/common/octeontx2 directory and it
> > > > > > > > has some API which Needs to shared between drivers not to
> > > > > > > > the application. For me, it does not make sense to go
> > > > > > > > through any ABI
> > > > > process in such case.
> > > > > > > >
> > > > > > > >
> > > > > > > Maybe not, but other drivers will have APIs designed for
> > > > > > > apps to call directly - some NIC drivers have them, and I
> > > > > > > suspect that rawdev drivers will need them a lot. Therefore,
> > > > > > > it's best to have the drivers directory scanned by our tooling.
> > > > > >
> > > > > > Agreed. But all of those API  which called directly called
> > > > > > from application is starts with rte_ symbol. How about
> > > > > > skipping the symbols which is NOT start with rte_*
> > > > > > example:
> > > > > > drivers/common/octeontx/rte_common_octeontx_version.map
> > > > > > drivers/common/dpaax/rte_common_dpaax_version.map
> > > > > >
> > > > >
> > > > > No, that won't work.  If you export a function, it doesn't
> > > > > matter if its named
> > > > > rte_* or not.  Its accessible from any library/application that
> > > > > cares to call it,
> > > >
> > > > IMO, The name prefix matters. The rte_* should denote it a DPDK
> > > > API and application suppose to use it.
> > > >
> > > It doesn't, its just a convention.  We have no documentation that
> > > indicates what the meaning of an rte_* prefix is specficially, above
> > > and beyond the fact thats how we name functions in the DPDK.  If you
> > > want to submit a patch to formalize the meaning of function
> > > prefixes, you're welcome too (though I won't support it, perhaps
> > > others will).  But even if you do, it doesn't address the underlying
> > > problem, which is that applications still have access to those symbols.
> > > Maintaining an ABI by assertion of prefix is really a lousy way to
> > > communicate what functions should be accessed by an application and
> > > which shouldn't.  If a function is exported, and included in the
> > > header file, people will try to use
> >
> > The current scheme in the driver/common is that, the header files are
> > NOT made It as public ie not installed make install.
> > The consumer driver includes that using relative path wrt DPDK source
> directory.
> >
> Well, thats a step in the right direction.  I'd still like to see some enforcement
> to prevent the inadvertent use of those APIs though

Yes header file  is  not exported. Not sure how a client can use those.
Other than doing some hacking.

> 
> > Anyway I will add experimental section to make tool happy.
> >
> That really not the right solution.  Marking them as experimental is just
> papering over the problem, and suggests to users that they will one day be
> stable. 

That what my original concern.

> What you want is to explicitly mark those symbols as internal only, so
> that any inadvertent use gets flagged.

What is your final thought? I can assume the following for my patch generation

# No need to mark as experimental
# Add @internal to denote it is a internal function like followed some places in EAL.

> 
> Neil
> >
> >


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