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 -