Re: [dpdk-dev] [PATCH RFC 00/13] Update build system

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

2015-01-22 10:03, Gonzalez Monroy, Sergio:
> > From: Gonzalez Monroy, Sergio
> > Sent: Monday, January 12, 2015 5:22 PM
> > To: Thomas Monjalon
> > Subject: Re: [dpdk-dev] [PATCH RFC 00/13] Update build system
> > 
> > Hi Thomas,
> > 
> > > From: Thomas Monjalon [mailto:thomas.monjalon@6wind.com]
> > > Sent: Monday, January 12, 2015 4:52 PM
> > >
> > > Hi Sergio,
> > >
> > > 2015-01-12 16:33, Sergio Gonzalez Monroy:
> > > > This patch series updates the DPDK build system.
> > >
> > > Thanks for proposing such rework.
> > > We need discussions on that topic. So I ask some questions below.
> > >
> > > > Following are the goals it tries to accomplish:
> > > >  - Create a library containing core DPDK libraries (librte_eal,
> > > >    librte_malloc, librte_mempool, librte_mbuf and librte_ring).
> > > >    The idea of core libraries is to group those libraries that are
> > > >    always required for any DPDK application.
> > >
> > > How is it better? Is it only to reduce dependencies lines?
> > >
> > In my opinion I think that there are a set of libraries that are always required
> > and therefore should be grouped as a single one.
> > Basically all apps and other DPDK libs would have dependencies to these core
> > libraries.
> > 
> > Aside from that, I don't think there is any difference. Note that this affects
> > shared libraries, with no difference for apps linked against static libs.
> > 
> > > >  - Remove config option to build a combined library.
> > >
> > > Why removing combined library? Is there people finding it helpful?
> > >
> > I don't think it makes sense from a shared library point of view, maybe it
> > does for static?
> > For example, in the case of shared libraries I think we want to try to avoid the
> > case where we have an app linked against librte_dpdk.so, but such library
> > may contain different libraries depending on the options that were enabled
> > when the lib was built.
> > 
> > The core libraries would be that set of libraries that are always required for
> > an app, and its content would be fixed regardless of the option libraries (like
> > acl, hash, distributor, etc.) We could add more libraries as core if we think it is
> > a better solution, but the goal should be that librte_core.so contains the
> > same libraries/API regardless of the system/arch.
> > 
> > > >  - For shared libraries, explicitly link against dependant
> > > >    libraries (adding entries to DT_NEEDED).
> > >
> > > OK, good.
> > >
> > > >  - Update app linking flags against static/shared DPDK libs.
> > > >
> > > > Note that this patch turns up being quite big because of moving lib
> > > > directories to a new subdirectory.
> > > > I have ommited the actual diff from the patch doing the move of
> > > > librte_eal as it is quite big (6MB). Probably a different approach
> > > > is
> > > preferred.
> > >
> > > Why do you think moving directories is needed?
> > >
> > Actually I am not sure is the best way to do this :) There is no need to move
> > them, as the same result could be achieved without moving directories, but I
> > thought that it would be easier for anyone to see which libraries are 'core'
> > and which are not.
> > 
> > Not moving those directories would definitely simplify this patch series.
> > 
> > > Thanks
> > > --
> > > Thomas
> > 
> > Thanks,
> > Sergio
> 
> Hi Thomas,
> 
> Any other comments/suggestions ? 
> My main concern would be the patch needed to move librte_eal (around 6MB). 
> 
> Thoughts?

I think you shouldn't move the libs.
Maybe we can link the core libs into one (not sure of the interest)
but I think we shouldn't move them in a core/ subdir.

On another side, I'd like to see KNI moving out of EAL.

-- 
Thomas