On 12/02/2015 09:22, Panu Matilainen wrote: > On 02/11/2015 01:11 PM, Gonzalez Monroy, Sergio wrote: >>> From: Neil Horman [mailto:nhorman at tuxdriver.com] >>> Sent: Friday, January 30, 2015 6:13 PM >>> To: Gonzalez Monroy, Sergio >>> Cc: Thomas Monjalon; dev at dpdk.org >>> Subject: Re: [dpdk-dev] [PATCH 0/8] Improve build process >>> >>> On Fri, Jan 30, 2015 at 05:38:49PM +0000, Gonzalez Monroy, Sergio >>> wrote: >> >> [snip] >> >>>> >>>> So would it be reasonable to add DT_NEEDED entries to all DPDK >>>> libraries >>> but EAL? >>>> If I understood what you were saying right, we could enforce the >>>> 'dependency' in the linker script with something like this: >>>> $ cat librte_eal.so >>>> INPUT( librte_eal.so.1 -lrte_mempool -lrte_malloc) We could have such >>>> linker script for librte_eal.so instead of the soft link once >>>> versioning is in place. >>>> >>> Correct. >>> >>>> Things that would be missing versus the proposed patch: >>>> - As I have mention in previous post, ldd info for EAL library >>>> would not >>> reflect >>>> its dependency to other DPDK libs. >>> librte_eal.so would no show those dependencies, as far as I know >>> (though I >>> haven't explicitly checked). The subordunate libraries included in >>> the input >>> line, may or may not show dependencies among themselves, depending on >>> your build setup (and the use of --no-as-needed and -l when linking the >>> individual .so libraries. >>> >>>> - I was enforcing resolving all references when building the >>>> libraries (-z >>> defs), so >>>> we either remove it altogether or skip eal. >>> I think thats correct, yes. >>> >>>> - All apps would show DT_NEEDED entries for a set of DPDK >>>> libraries that >>>> in most cases are required (eal, mempool, malloc, mbuf, ring VS >>>> dpdk_core) >>>> >>> I think apps linked to libdpdk_core would have DT_NEEDED entries for >>> libdpdk_core, not the subordonate libraries (though check me on that >>> to be >>> sure). >>> >> Just checked on this and they do link against the subordinate >> libraries, although >> It does not really matter as we are dropping the 'core' library >> approach anyway. >> >>>> I think that the linker script approach is reasonable if we prefer to >>>> go that way instead of creating a core library. >>>> >>> I think it would make sense from a build environment point of view, >>> in that it >>> allows library specific flags to be incorporated properly. I think >>> the only >>> downside is that the individual libraries still need to be carried >>> around >>> (though they can be ignored from an application build/run standpoint). >>> You're question should probably be asked of people using COMBINED_LIBS >>> currently to make sure that meets their needs, though I think it will. >>> >>> Neil >>> >> So I just realized that I was not having into account a possible >> scenario, where >> we have an app built with static dpdk libs then loading a dso with >> -d option. >> >> In such case, because the pmd would have DT_NEEDED entries, dlopen >> will fail. >> So to enable such scenario we would need to build PMDs without DT_NEEDED >> entries. > > Hmm, for that to be a problem you'd need to have the PMD built against > shared dpdk libs and while the application is built against static > dpdk libs. I dont think that's a supportable scenario in any case. > > Or is there some other scenario that I'm not seeing? > > - Panu - > I agree with you. I suppose it comes down to, do we want to support such scenario?
From what I can see, it seems that we do currently support such scenario by building dpdk apps against all static dpdk libs using --whole-archive (all libs and not only PMDs). http://dpdk.org/browse/dpdk/commit/?id=20afd76a504155e947c770783ef5023e87136ad8 Am I misunderstanding this? Regards, Sergio