Re: [dpdk-dev] [PATCH v3 1/5] mk: remove combined library and related options

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

2015-04-09 07:19, Neil Horman:
> On Thu, Apr 09, 2015 at 12:06:47PM +0300, Avi Kivity wrote:
> > On 04/09/2015 11:33 AM, Gonzalez Monroy, Sergio wrote:
> > >On 08/04/2015 19:26, Stephen Hemminger wrote:
> > >>On Wed,  8 Apr 2015 16:07:21 +0100
> > >>Sergio Gonzalez Monroy <sergio.gonzalez.monroy@intel.com> wrote:
> > >>
> > >>>Currently, the target/rules to build combined libraries is different
> > >>>than the one to build individual libraries.
> > >>>
> > >>>By removing the combined library option as a build configuration option
> > >>>we simplify the build pocess by having a single point for
> > >>>linking/archiving
> > >>>libraries in DPDK.
> > >>>
> > >>>This patch removes CONFIG_RTE_BUILD_COMBINE_LIB build config option and
> > >>>removes the makefiles associated with building a combined library.
> > >>>
> > >>>The CONFIG_RTE_LIBNAME config option is kept as it will be use to
> > >>>always generate a linker script that acts as a single combined library.
> > >>>
> > >>>Signed-off-by: Sergio Gonzalez Monroy
> > >>><sergio.gonzalez.monroy@intel.com>
> > >>No. We use combined library and it greatly simplfies the application
> > >>linking process.
> > >>
> > >After all the opposition this patch had in v2, I did explain the current
> > >issues
> > >(see http://dpdk.org/ml/archives/dev/2015-March/015366.html ) and this was
> > >the agreed solution.
> > >
> > >As I mention in the cover letter (also see patch 2/5), building DPDK
> > >(after applying this patch series) will always generate a very simple
> > >linker script that behaves as a combined library.
> > >I encourage you to apply this patch series and try to build your app
> > >(which links against combined lib).
> > >Your app should build without problem unless I messed up somewhere and it
> > >needs fixing.
> > 
> > Is it possible to generate a pkgconfig file (dpdk.pc) that contains all of
> > the setting needed to compile and link with dpdk?  That will greatly
> > simplify usage.
> > 
> > A linker script is just too esoteric.
> > 
> Why esoteric?  We're not talking about a linker script in the sense of a binary
> layout file, we're talking about a prewritten/generated libdpdk_core.so that
> contains linker directives to include the appropriate libraries.  You link it
> just like you do any other library, but it lets you ignore how they are broken
> up.
> 
> We could certainly do a pkg-config file, but I don't think thats any more
> adventageous than this solution.

As already commented (http://dpdk.org/ml/archives/dev/2015-March/015367.html),
pkgconfig could be something useful in any case (single or multi-libraries).
Having a linker script to replace the single ("combined") library may be
convenient in some cases but do not replace pkgconfig.