Re: Sharing Common libs between PMDs

[Jerin Jacob <jerin.jacob@caviumnetworks.com>]

-----Original Message-----
> Date: Wed, 14 Mar 2018 17:38:14 +0000
> From: Shreyansh Jain <shreyansh.jain@nxp.com>
> To: "Trahe, Fiona" <fiona.trahe@intel.com>, "Richardson, Bruce"
>  <bruce.richardson@intel.com>, Jerin Jacob <jerin.jacob@caviumnetworks.com>
> CC: Liron Himi <lironh@marvell.com>, "dev@dpdk.org" <dev@dpdk.org>,
>  "Jozwiak, TomaszX" <tomaszx.jozwiak@intel.com>
> Subject: RE: [dpdk-dev] Sharing Common libs between PMDs
> 
> > -----Original Message-----
> > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Trahe, Fiona
> > Sent: Wednesday, March 14, 2018 9:41 PM
> > To: Richardson, Bruce <bruce.richardson@intel.com>; Jerin Jacob
> > <jerin.jacob@caviumnetworks.com>
> > Cc: Liron Himi <lironh@marvell.com>; dev@dpdk.org; Trahe, Fiona
> > <fiona.trahe@intel.com>; Jozwiak, TomaszX <tomaszx.jozwiak@intel.com>
> > Subject: Re: [dpdk-dev] Sharing Common libs between PMDs
> > 
> > 
> > 
> > > -----Original Message-----
> > > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Bruce Richardson
> > > Sent: Wednesday, March 14, 2018 3:05 PM
> > > To: Jerin Jacob <jerin.jacob@caviumnetworks.com>
> > > Cc: Liron Himi <lironh@marvell.com>; dev@dpdk.org
> > > Subject: Re: [dpdk-dev] Sharing Common libs between PMDs
> > >
> > > On Wed, Mar 14, 2018 at 08:25:45PM +0530, Jerin Jacob wrote:
> > > > -----Original Message-----
> > > > > Date: Wed, 14 Mar 2018 09:34:40 +0000
> > > > > From: Liron Himi <lironh@marvell.com>
> > > > > To: "dev@dpdk.org" <dev@dpdk.org>
> > > > > CC: Liron Himi <lironh@marvell.com>
> > > > > Subject: [dpdk-dev] Sharing Common libs between PMDs
> > > > >
> > > > > Hi,
> > > > >
> > > > > We have several PMDs in DPDK that are using the same underlying
> > common libraries.
> > > > > In addition, we have plans to add some new common service into
> > DPDK that already introduces too
> > > much complexity with the way that the code is written now.
> > > > > Therefore, we would like to move all our common functions calls
> > into one shared/common folder in
> > > DPDK and we need to find proper place for this purpose.
> > > > >
> > > > > Can you suggest on such a place?
> > > >
> > > > There was an attempt to create "driver/common" but latter the
> > common code
> > > > for NXP HW device got moved to drivers/bus/dpaa/. Linux kernel has
> > > > something called "driver/soc", I think, "driver/soc" may be more
> > appropriate.
> > > >
> > > > Currently DPDK's driver build dependency is in the following order
> > > > (bus, mempool, net, crypto, event).
> > > > Other than driver/common or driver/soc, one option could be to
> > > > - Move the common code to bus or mempool
> > > > and
> > > > - Across the drivers, include the header files through CFLAGS if
> > the common code
> > > >   is in header file
> > > >
> > https://emea01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fdpdk.
> > org%2Fbrowse%2Fdpdk%2Ftree%2Fdrivers%2Fevent%2Focteontx%2FMakefile%23n1
> > 3&data=02%7C01%7Cshreyansh.jain%40nxp.com%7Cfa7ba7a1dfd94b9336c008d589c
> > 63dd7%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C636566406955506340&s
> > data=MkxFJUuHPuBFIqAgjmUzUcgRms9WTsxkkMQah4kGAlM%3D&reserved=0
> > > >
> > > Given that this seems to be a recurring problem, I think having a
> > > drivers/common folder may not be a bad thing.
> > >
> > > /Bruce
> > We've been grappling with the same problem for QAT driver.
> > A variant we were about to propose was to rename drivers/bus to
> > drivers/lib.
> > And possibly move drivers/mempool to drivers/lib
> > As the rest of the drivers/xxx are actually PMDs, while mempool and bus
> > are libs
> > on which other drivers depend.
> > I'm ok with adding a drivers/common instead, but the above seems
> > cleaner.
> 
> In my opinion, I think we should add a common/ without modifying the bus/mempool structure. I agree that bus/mempool are not standalone PMDs themselves, but they are not libraries either in true sense - they /plug/ into the eal framework and *may* provide service to drivers. 
> 
> As for common/ - that gets a +1 from me.

+1 for drivers/common