On 12/02/2015 05:41, Neil Horman wrote: > On Wed, Feb 11, 2015 at 11:11:13AM +0000, 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. >> > ok, understood. > >>>> 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. >> > This is very true, but I was under the impression that the only things that > were > dlopen-able were PMD's, which would not be part of the core library. Was I > mistaken? As far as I know you are right that only PMDs are being dlopen. The proposed patch though, added DT_NEEDED entries for PMDs too, so they would need to be left empty for them to work in such scenario.
Is that reasonable? Regards, Sergio >> 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. >> >> Thoughts? >> > As I mentioned above I thought the only thing that would typically be > referenced > via dlopen would be libraries that were not part of the unified core library. > if thats not the case, then yes, we need a little more thought here > Neil > >> Regards, >> Sergio >>
