From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qg0-f53.google.com (mail-qg0-f53.google.com [209.85.192.53]) by dpdk.org (Postfix) with ESMTP id DA775ADFC for ; Fri, 20 May 2016 14:42:13 +0200 (CEST) Received: by mail-qg0-f53.google.com with SMTP id f92so59370303qgf.0 for ; Fri, 20 May 2016 05:42:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=canonical-com.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=IXJSEno8uCLsa0L5zLybLRCF1vx2kGvXsYo/y5le7is=; b=J91NkyoYjWpQyjC3yjgh84AMsjAhxY34zdj9PpyBB/TtbcZBvVyXp83zRav6hsSYev ZyWEnaT0AW6775h49/L5KRHxdhUuLXmUzwQiYxRD12vBS84HZ/IwNjj553VW5IphITzS NGsz5zj7MifuIqyvIKadfPeXgzj36neLJ6AaNjYIjPqoTXJBFKHRZ+DCZnuyQEo4+x3q At29BGXLEo79WLCB1xFTnPxuB1MEEuMcoQGX7CrfyYeyNUygw+95F2pXgkl28PTHVObp XQYaY7wPMu+7tZ5dJATYI2acsqSquL0YGEYGRCZ8nJfMFzarB+Kr86l23aS+ionn/akx W8ug== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=IXJSEno8uCLsa0L5zLybLRCF1vx2kGvXsYo/y5le7is=; b=kkkya3rvGc3pbzWeKpFo+xIQmnSTFyZkw7PoNEmd9Nbm5Ie+2IE8NK7I+nhSOSVHih Zeu0fU6fVSYNtnXYIot+bix3LLErR3tO1D+xUbBFXtTZOo17cOQgc70ZlqYWEb3LI90b B37ZfNlYCHfpN+vRxLiO/4u25nrKOKUESjvU9rJywCU7qXTHReEhzb9e+z2fejDV7xv1 vKJhaqQnM92sSIZlX6aixe2FQteJrqRzMRcSSSUFgyBEe7RGnt9gJxgKbbYph2VUzpIc 2Gu7EX2Dg0O2uoODneR1JVWT6e3ee5qVOO1HQVqlreoMKLgisqwcF/Wa39F3vlmTbFle NEdA== X-Gm-Message-State: AOPr4FVdXNqd28ec8WEP4sOkjnO/g4jo7Di24ezG0JX6nnzlsbQ9fPgWPo3xg2STLBET/XXbZukI1zkhh5glY4U5 X-Received: by 10.140.108.247 with SMTP id j110mr2903819qgf.54.1463748132592; Fri, 20 May 2016 05:42:12 -0700 (PDT) MIME-Version: 1.0 Received: by 10.55.97.3 with HTTP; Fri, 20 May 2016 05:41:53 -0700 (PDT) In-Reply-To: References: <2785570.uvvpCYCSoT@xps13> From: Christian Ehrhardt Date: Fri, 20 May 2016 14:41:53 +0200 Message-ID: To: Panu Matilainen Cc: Thomas Monjalon , dev Content-Type: text/plain; charset=UTF-8 X-Content-Filtered-By: Mailman/MimeDel 2.1.15 Subject: Re: [dpdk-dev] Underlinked libs and overlinked applications - an issue? X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 20 May 2016 12:42:14 -0000 On Fri, May 20, 2016 at 1:01 PM, Panu Matilainen 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.