From: Christian Ehrhardt <christian.ehrhardt@canonical.com>
To: Panu Matilainen <pmatilai@redhat.com>
Cc: Thomas Monjalon <thomas.monjalon@6wind.com>, dev <dev@dpdk.org>
Subject: Re: [dpdk-dev] Underlinked libs and overlinked applications - an issue?
Date: Fri, 20 May 2016 18:43:37 +0200 [thread overview]
Message-ID: <CAATJJ0KCLxdZjurkzsbps6BijkFFr2pHb6ysvCRQWuwRPLXWAw@mail.gmail.com> (raw)
In-Reply-To: <CAATJJ0KBTA1KPdb-ZaSFGLP6UCKORLZ-O75euo3PhnbKiAG0DQ@mail.gmail.com>
ok,
- little baby steps first
I'll submit a trivial patch in reply to this fixing the underlinking in
all .so's, except librte_eal.
- discussion on the remaining open issue second.
For the remaining issue I think that needs a special understanding of
linkers I still need to grasp.
But since I failed to find a good explanation for the exact case we face
here I put it in a generalized form on StackOverflow so eventually more
than just us can benefit from the answer once/if we find an answer.
So to all of you - if you are not scared of the latter pages of ld/gcc man
pages :-) feel free to take a look at
http://stackoverflow.com/questions/37351699/how-to-create-both-so-files-for-two-circular-depending-libraries
For us, but not important for the question in general:
liba = librte_eal, libb = librte_mempool
(and ring, ivshmem, but once it is solved once it is solved)
Time to stip for now, have a great Weekend
Christian
Christian Ehrhardt
Software Engineer, Ubuntu Server
Canonical Ltd
On Fri, May 20, 2016 at 2:41 PM, Christian Ehrhardt <
christian.ehrhardt@canonical.com> wrote:
> On Fri, May 20, 2016 at 1:01 PM, Panu Matilainen <pmatilai@redhat.com>
> wrote:
>
>> On 05/19/2016 09:17 PM, Thomas Monjalon wrote:
>>
>>> 2016-05-19 17:38, Christian Ehrhardt:
>>>
>>>> Hi,
>>>> I was working on the new 16.04 build system to adapt deb packaging to
>>>> it.
>>>> I remember somewhen back in the DPDK 2.2 and shared+combined library
>>>> days I
>>>> had some issues with over/underlinking - but it seems those are still
>>>> existent or came back.
>>>>
>>>
>>> I would say it has always been like that.
>>> Thanks for raising the issue.
>>>
>>> After a build in almost default config (just disabled the kernel modules)
>>>> and set RTE_MACHINE to default I find the following.
>>>>
>>>> #1
>>>> The libraries are all only linked against external things - even clearly
>>>> using internal structures:
>>>> ldd usr/lib/x86_64-linux-gnu/librte_lpm.so.2
>>>> linux-vdso.so.1 => (0x00007fff7e7a5000)
>>>> libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f175d4dd000)
>>>> /lib64/ld-linux-x86-64.so.2 (0x0000558d3afbf000)
>>>>
>>>
>>> The DT_NEEDED entries are created only for external dependencies.
>>> Probably we should create ones for internal dependencies based on the
>>> variable DEPDIRS-y.
>>>
>>
>> Yes, DT_NEEDED for internal dependencies are needed too, see eg recent
>> commits c6417ce61f83 and 8180554d82b3. That was part of Sergios' build
>> system improvement patch series last spring or so (but since then
>> abandoned), I picked up the work and been doing it in smaller pieces. Phase
>> 1 was the external dependencies, phase 2 is internal dependencies which I'm
>> working on. Unfortunately health issues have stalled my work a lot recently
>> :-/
>
>
> Since I work on 16.04 as released currently I almost missed those, but I
> at least remember seeing the first on the list.
> I had almost the same change - adopting yours since it is accepted.
> Maybe I can provide a few more baby steps on that path - or at least a few
> more pieces for discussion and review.
> I hope you get well soon Panu!
>
>
>> #2
>>>> The Application then seem to try to make up for that by realizing all
>>>> that
>>>> is missing.
>>>> But looking at the app alone it seems overlinked by that - it is not
>>>> using
>>>> all of these on its own.
>>>> ldd usr/bin/cmdline_test
>>>> linux-vdso.so.1 => (0x00007ffeec9ea000)
>>>> librte_distributor.so.1 => not found
>>>> librte_reorder.so.1 => not found
>>>> [...]
>>>> librte_jobstats.so.1 => not found
>>>> [...]
>>>> And for example none of the librte_jobstats.so.1 symbols are used
>>>> "directly" in there.
>>>>
>>>
>>> Yes every libraries are put for every apps in rte.app.mk.
>>> Probably that we could better use DEPDIRS-y for apps.
>>>
>>>
>> Another trick from Sergios' original patch series is to utilize
>> AS_NEEDED() in the linker script, so it ends up looking something like this
>> for shared library config (static would remain as it is now):
>>
>> INPUT ( librte_eal librte_mempool librte_ring
>> AS_NEEDED ( librte_acl librte_timer librte_vhost <...> )
>> )
>>
>> ...and then use the linker script for linking the apps, which should
>> simplify rte.app.mk considerably. Or so the theory goes. Anyway, the
>> above requires DT_NEEDED for the internal libraries to be present first,
>> but once all these pieces are in place, dynamically linked apps will only
>> link to the libraries they actually need.
>>
>
> Interesting approach, I wasn't even working on DPDK back then - that could
> really simplify the mk there.
> I was experimenting with just dropping the "no-as-needed" in
> mk/exec-env/linuxapp/rte.vars.mk, but that seems to shoot too far -
> haven't had the time to look deeper.
> Interested if your approach could help.
>
> But the other part of it - getting the proper DT_NEEDED into the libs (I
> also consider underlinking worse than overlinking) seems to be just missing
> a bunch of -l - my last test build looked fine.
> There is the underlinking issue of librte_eal left that Sergio mentioned
> back in 6d25d90c, but it seems to be the next baby step to solve most else
> of the underlinking.
> I'll adapt it to git level and at least throw it out for discussion later
> on.
>
>
next prev parent reply other threads:[~2016-05-20 16:43 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-19 15:38 Christian Ehrhardt
2016-05-19 18:17 ` Thomas Monjalon
2016-05-20 11:01 ` Panu Matilainen
2016-05-20 12:41 ` Christian Ehrhardt
2016-05-20 16:43 ` Christian Ehrhardt [this message]
2016-05-20 16:50 ` [dpdk-dev] [PATCH] mk: fix underlinking issues of most librte libraries Christian Ehrhardt
2016-05-20 17:08 ` Thomas Monjalon
2016-05-24 9:56 ` Panu Matilainen
2016-05-24 10:11 ` Christian Ehrhardt
2016-05-26 13:13 ` Ferruh Yigit
2016-05-27 5:59 ` Panu Matilainen
2016-05-27 16:15 ` Ferruh Yigit
2016-05-27 16:48 ` [dpdk-dev] [PATCH 1/2] mk: prevent overlinking in applications Ferruh Yigit
2016-05-27 16:48 ` [dpdk-dev] [PATCH 2/2] mk: reduce scope of whole-archive to pmd libraries Ferruh Yigit
2016-06-10 9:03 ` Thomas Monjalon
2016-06-10 9:57 ` Ferruh Yigit
2016-06-10 10:18 ` Thomas Monjalon
2016-06-10 11:06 ` Ferruh Yigit
2016-06-10 12:21 ` Thomas Monjalon
2016-06-10 13:35 ` Ferruh Yigit
2016-06-09 10:10 ` [dpdk-dev] [PATCH 1/2] mk: prevent overlinking in applications Thomas Monjalon
2016-06-09 13:05 ` Ferruh Yigit
2016-06-10 13:19 ` [dpdk-dev] [PATCH v2 0/6] reduce " Thomas Monjalon
2016-06-10 13:19 ` [dpdk-dev] [PATCH v2 1/6] mk: sort drivers in static application link list Thomas Monjalon
2016-06-10 13:19 ` [dpdk-dev] [PATCH v2 2/6] mk: fix driver dependencies order for static application Thomas Monjalon
2016-06-10 14:49 ` Ferruh Yigit
2016-06-10 14:54 ` Thomas Monjalon
2016-06-10 13:19 ` [dpdk-dev] [PATCH v2 3/6] mk: remove library grouping during application linking Thomas Monjalon
2016-06-10 14:54 ` Ferruh Yigit
2016-06-10 15:14 ` Thomas Monjalon
2016-06-10 13:19 ` [dpdk-dev] [PATCH v2 4/6] mk: prevent overlinking in applications Thomas Monjalon
2016-06-10 14:56 ` Ferruh Yigit
2016-06-10 15:15 ` Thomas Monjalon
2016-06-10 13:19 ` [dpdk-dev] [PATCH v2 5/6] mk: sort libraries in level order when linking Thomas Monjalon
2016-06-10 13:19 ` [dpdk-dev] [PATCH v2 6/6] mk: reduce scope of whole-archive static linking Thomas Monjalon
2016-06-10 15:03 ` Ferruh Yigit
2016-06-10 15:18 ` Thomas Monjalon
2016-06-10 18:32 ` [dpdk-dev] [PATCH v3 0/6] reduce overlinking in applications Ferruh Yigit
2016-06-10 18:32 ` [dpdk-dev] [PATCH v3 1/6] mk: sort drivers in static application link list Ferruh Yigit
2016-06-10 19:38 ` Wiles, Keith
2016-06-10 18:32 ` [dpdk-dev] [PATCH v3 2/6] mk: fix driver dependencies order for static application Ferruh Yigit
2016-06-10 18:32 ` [dpdk-dev] [PATCH v3 3/6] mk: sort libraries when linking, move pmd libs to higher level Ferruh Yigit
2016-06-13 9:29 ` Thomas Monjalon
2016-06-13 10:04 ` Ferruh Yigit
2016-06-13 10:21 ` Thomas Monjalon
2016-06-13 10:29 ` Ferruh Yigit
2016-06-10 18:32 ` [dpdk-dev] [PATCH v3 4/6] mk: sort libraries when linking, move external libs to lower level Ferruh Yigit
2016-06-10 18:32 ` [dpdk-dev] [PATCH v3 5/6] mk: remove library grouping during application linking Ferruh Yigit
2016-06-10 18:32 ` [dpdk-dev] [PATCH v3 6/6] mk: prevent overlinking in applications Ferruh Yigit
2016-06-11 6:34 ` Thomas Monjalon
2016-06-13 9:05 ` Ferruh Yigit
2016-06-13 9:24 ` Christian Ehrhardt
2016-06-13 9:48 ` [dpdk-dev] [PATCH] mk: fix missing DEPDIRS to avoid libarary underlinking Christian Ehrhardt
2016-06-13 10:08 ` Thomas Monjalon
2016-06-13 10:20 ` Christian Ehrhardt
2016-06-13 11:06 ` [dpdk-dev] [PATCH v2 0/2] mk: fix more library underlinking Christian Ehrhardt
2016-06-13 11:06 ` [dpdk-dev] [PATCH v2 1/2] mk: fix missing vhost dependency to pthread to avoid libarary underlinking Christian Ehrhardt
2016-06-13 11:06 ` [dpdk-dev] [PATCH v2 2/2] mk: fix missing DEPDIRS " Christian Ehrhardt
2016-06-13 14:16 ` [dpdk-dev] [PATCH v2 0/2] mk: fix more library underlinking Thomas Monjalon
2016-06-13 14:14 ` [dpdk-dev] [PATCH v2 0/6] reduce overlinking in applications Thomas Monjalon
2016-06-07 8:23 ` [dpdk-dev] [PATCH] mk: fix underlinking issues of most librte libraries Thomas Monjalon
2016-06-07 9:25 ` Panu Matilainen
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