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

[Jerin Jacob Kollanukkaran <jerinj@marvell.com>]

> -----Original Message-----
> From: Neil Horman <nhorman@tuxdriver.com>
> Sent: Wednesday, May 22, 2019 6:16 PM
> To: Jerin Jacob Kollanukkaran <jerinj@marvell.com>
> Cc: dev@dpdk.org; thomas@monjalon.net; stable@dpdk.org
> Subject: Re: [EXT] Re: [dpdk-dev] [PATCH] devtools: skip the symbol check
> when map file under drivers
> 
> On Wed, May 22, 2019 at 03:05:54AM +0000, Jerin Jacob Kollanukkaran
> wrote:
> > > -----Original Message-----
> > > From: Neil Horman <nhorman@tuxdriver.com>
> > > Sent: Wednesday, May 22, 2019 1:57 AM
> > > To: Jerin Jacob Kollanukkaran <jerinj@marvell.com>
> > > Cc: dev@dpdk.org; thomas@monjalon.net; stable@dpdk.org
> > > Subject: [EXT] Re: [dpdk-dev] [PATCH] devtools: skip the symbol
> > > check when map file under drivers
> > >
> > > On Wed, May 22, 2019 at 01:26:28AM +0530, jerinj@marvell.com wrote:
> > > > From: Jerin Jacob <jerinj@marvell.com>
> > > >
> > > > Drivers do not have ABI.
> > > > Skip the symbol check if map file under drivers directory.
> > > >
> > > > Fixes: 4bec48184e33 ("devtools: add checks for ABI symbol
> > > > addition")
> > > >
> > > > Cc: stable@dpdk.org
> > > > Cc: Neil Horman <nhorman@tuxdriver.com>
> > > >
> > > 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?
> >
> Yes, they definately should, they are API's just as any other in the core DPDK
> library.

OK


> 
> > 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?
> >
> No, Thats just one case, and if those calls are between drivers, so be it, but
> those still need to be stable, and we have other examples (like the bonding
> or dummy driver), which have additional APIs that are explicitly meant to be
> used by an application.

There is no disagreement on the API that exposed to application.
I am concerned with internal driver APIs. For example, I am getting following warning

ERROR: symbol otx2_mbox_alloc_msg_rsp is added in the DPDK_19.05 section, but is expected to be added in the EXPERIMENTAL section of the version map

This API suppose to be called only a octeontx2 network driver from octeontx2 common driver
i.e application should not expect any stability on intra driver functions or it does not meant to
be used by application.

Thomas,
Any thought on this?



> 
> > 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.
> >
> Why?  If you create an API thats reachable from another block of code (be it
> a driver or an application), you've created a dependency in which that API
> must remain stable, lest you risk breaking something.  If an end user writes
> an out-of-tree PMD which makes use of an an additional driver API, then you
> need to keep it stable or you will break them.
> 
> >
> > > dpaa2 driver is a good example, the cryptodev scheduler is another.
> > > Take a look at their version.map files to see what I mean.
> > >
> > > Unless we are willing to make drivers opaque objects that are only
> > > accessible from the [eth|crypto|etc]dev apis in the DPDK core, we
> > > have the potential for exported symbols, which means we have an ABI
> > > that has to be maintained, or at least recognized and reviewed for
> > > consistency
> > >
> > > Nacked-by: Neil Horman <nhorman@tuxdriver.com>
> > >
> > >
> > > > Signed-off-by: Jerin Jacob <jerinj@marvell.com>
> > > > ---
> > > >  devtools/check-symbol-change.sh | 8 ++++++++
> > > >  1 file changed, 8 insertions(+)
> > > >
> > > > diff --git a/devtools/check-symbol-change.sh
> > > > b/devtools/check-symbol-change.sh index c5434f3bb..444beddad
> > > > 100755
> > > > --- a/devtools/check-symbol-change.sh
> > > > +++ b/devtools/check-symbol-change.sh
> > > > @@ -93,6 +93,14 @@ check_for_rule_violations()
> > > >  		if [ "$ar" = "add" ]
> > > >  		then
> > > >
> > > > +			directory=`echo $mname | cut -d / -f 2`
> > > > +			if [ "$directory" = "drivers" ]
> > > > +			then
> > > > +				# Drivers do not have ABI. Skip further
> > > > +				# processing if the map file is under
> > > > +				# drivers directory
> > > > +				continue
> > > > +			fi
> > > >  			if [ "$secname" = "unknown" ]
> > > >  			then
> > > >  				# Just inform the user of this occurrence, but
> > > > --
> > > > 2.21.0
> > > >
> > > >
> >