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

[Gonzalez Monroy, Sergio]

Hi Thomas,

> From: Thomas Monjalon [mailto:thomas.monjalon at 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