From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: <konstantin.ananyev@intel.com> Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by dpdk.org (Postfix) with ESMTP id 4B4FD595A for <dev@dpdk.org>; Tue, 3 Mar 2015 17:24:13 +0100 (CET) Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga102.jf.intel.com with ESMTP; 03 Mar 2015 08:22:45 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.09,682,1418112000"; d="scan'208";a="461935933" Received: from irsmsx106.ger.corp.intel.com ([163.33.3.31]) by FMSMGA003.fm.intel.com with ESMTP; 03 Mar 2015 08:17:56 -0800 Received: from irsmsx105.ger.corp.intel.com ([169.254.7.117]) by IRSMSX106.ger.corp.intel.com ([169.254.8.235]) with mapi id 14.03.0195.001; Tue, 3 Mar 2015 16:24:06 +0000 From: "Ananyev, Konstantin" <konstantin.ananyev@intel.com> To: Marc Sune <marc.sune@bisdn.de>, "Richardson, Bruce" <bruce.richardson@intel.com> Thread-Topic: [dpdk-dev] [PATCH] mk: add support for gdb debug info generation Thread-Index: AQHQTpX7K/KSn4KDi0q/6hBZ4HLQyZ0JgHeAgAEMsoCAAC5AgIAABfAAgAAEXYCAAAHfgIAABshwgAAUKoCAABs3AA== Date: Tue, 3 Mar 2015 16:24:05 +0000 Message-ID: <2601191342CEEE43887BDE71AB977258213F3A03@irsmsx105.ger.corp.intel.com> References: <1396546285-29972-1-git-send-email-cchemparathy@tilera.com> <2601191342CEEE43887BDE71AB9772580EF948F7@IRSMSX105.ger.corp.intel.com> <54E9C2C0.3090108@bisdn.de> <54F49E9D.6070201@bisdn.de> <20150303093355.GA7300@bricha3-MOBL3> <54F5A6CF.2090203@bisdn.de> <54F5ABCA.4010707@redhat.com> <54F5AF73.1060109@bisdn.de> <20150303130301.GA11084@bricha3-MOBL3> <2601191342CEEE43887BDE71AB977258213F38C9@irsmsx105.ger.corp.intel.com> <54F5C79F.1090705@bisdn.de> In-Reply-To: <54F5C79F.1090705@bisdn.de> Accept-Language: en-IE, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [163.33.239.180] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Cc: "dev@dpdk.org" <dev@dpdk.org> Subject: Re: [dpdk-dev] [PATCH] mk: add support for gdb debug info generation X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK <dev.dpdk.org> List-Unsubscribe: <http://dpdk.org/ml/options/dev>, <mailto:dev-request@dpdk.org?subject=unsubscribe> List-Archive: <http://dpdk.org/ml/archives/dev/> List-Post: <mailto:dev@dpdk.org> List-Help: <mailto:dev-request@dpdk.org?subject=help> List-Subscribe: <http://dpdk.org/ml/listinfo/dev>, <mailto:dev-request@dpdk.org?subject=subscribe> X-List-Received-Date: Tue, 03 Mar 2015 16:24:14 -0000 > -----Original Message----- > From: Marc Sune [mailto:marc.sune@bisdn.de] > Sent: Tuesday, March 03, 2015 2:39 PM > To: Ananyev, Konstantin; Richardson, Bruce > Cc: dev@dpdk.org > Subject: Re: [dpdk-dev] [PATCH] mk: add support for gdb debug info genera= tion >=20 >=20 > On 03/03/15 14:31, Ananyev, Konstantin wrote: > > > >> -----Original Message----- > >> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Bruce Richardson > >> Sent: Tuesday, March 03, 2015 1:03 PM > >> To: Marc Sune > >> Cc: dev@dpdk.org > >> Subject: Re: [dpdk-dev] [PATCH] mk: add support for gdb debug info gen= eration > >> > >> On Tue, Mar 03, 2015 at 01:56:19PM +0100, Marc Sune wrote: > >>> On 03/03/15 13:40, Panu Matilainen wrote: > >>>> On 03/03/2015 02:19 PM, Marc Sune wrote: > >>>>> On 03/03/15 10:33, Bruce Richardson wrote: > >>>>>> On Mon, Mar 02, 2015 at 06:32:13PM +0100, Marc Sune wrote: > >>>>>>> On 22/02/15 12:51, Marc Sune wrote: > >>>>>>>> I don't like the proposed patch, but I am recovering this old th= read > >>>>>>>> because I agree on the problem statement. > >>>>>>>> > >>>>>>>> On 04/04/14 11:57, Ananyev, Konstantin wrote: > >>>>>>>>> Hi Cyril, > >>>>>>>>> We already do have 'EXTRA_CFLAGS' and 'EXTRA_LDFLAGS' that you > >>>>>>>>> can use > >>>>>>>>> to enable debug, or any other compiler/linker options you need. > >>>>>>>>> Wonder, why that is not enough? > >>>>>>>> EXTRA_FLAGS var affects all the DPDK libraries. I was wondering = why > >>>>>>>> setting individually: > >>>>>>>> > >>>>>>>> diff --git a/config/common_linuxapp b/config/common_linuxapp > >>>>>>>> index 2f9643b..04adc0d 100644 > >>>>>>>> --- a/config/common_linuxapp > >>>>>>>> +++ b/config/common_linuxapp > >>>>>>>> @@ -127,7 +127,7 @@ CONFIG_RTE_LIBRTE_KVARGS=3Dy > >>>>>>>> # Compile generic ethernet library > >>>>>>>> # > >>>>>>>> CONFIG_RTE_LIBRTE_ETHER=3Dy > >>>>>>>> -CONFIG_RTE_LIBRTE_ETHDEV_DEBUG=3Dn > >>>>>>>> +CONFIG_RTE_LIBRTE_ETHDEV_DEBUG=3Dy > >>>>>>>> > >>>>>>>> > >>>>>>>> to put an example, does not set -g and -O0 in that particular mo= dule > >>>>>>>> only. > >>>>>>>> No one would ever use something compiled in DEBUG in production > >>>>>>>> anyway. > >>>>>>>> > >>>>>>>> I always end up modifying manually Makefiles in the lib library = that > >>>>>>>> I am > >>>>>>>> interested in having insides, overriding CFLAGS=3D-O3, which is = not > >>>>>>>> that > >>>>>>>> nice. > >>>>>>> I would like some feedback on this idea. If the community sees > >>>>>>> benefit, I > >>>>>>> will work on a patch for this. > >>>>>>> > >>>>>>> Marc > >>>>>>> > >>>>>> So, your proposal is to patch things so that any time one sets DEB= UG=3Dy > >>>>>> in the > >>>>>> build-time config for a library, we change the '-O3' to '-O0' and = set > >>>>>> -g also. > >>>>>> Correct? > >>>>> I am not sure what you mean by 'patch things'. I would simply enabl= e the > >>>>> build system to override the default compilation flags (now DPDK-wi= de, > >>>>> or specifically librte_ wide) when _DEBUG=3Dy for a library, changi= ng > >>>>> compilation flags from -O3 to -O0 -g and possibly also -fno-inline.= I > >>>>> have to check if -O0 already implicitly means -fno-inline (even for > >>>>> __attribute__((always_inline)) ). > >>>>> > >>>>> I did a quick test. I chose KNI because it didn't have a DEBUG flag= for > >>>>> the user-space library. For other libraries, the existing _DEBUG se= tting > >>>>> would be enough: > >>>>> > >>>>> marc@dpdk:~/dpdk$ git diff HEAD > >>>>> diff --git a/config/common_linuxapp b/config/common_linuxapp > >>>>> index 97f1c9e..8a3cef8 100644 > >>>>> --- a/config/common_linuxapp > >>>>> +++ b/config/common_linuxapp > >>>>> @@ -405,6 +405,7 @@ CONFIG_RTE_LIBRTE_PIPELINE=3Dy > >>>>> # > >>>>> CONFIG_RTE_LIBRTE_KNI=3Dy > >>>>> CONFIG_RTE_KNI_PREEMPT_DEFAULT=3Dy > >>>>> +CONFIG_RTE_LIBRTE_KNI_DEBUG=3Dy > >>>>> CONFIG_RTE_KNI_KO_DEBUG=3Dn > >>>>> CONFIG_RTE_KNI_VHOST=3Dn > >>>>> CONFIG_RTE_KNI_VHOST_MAX_CACHE_SIZE=3D1024 > >>>>> diff --git a/lib/librte_kni/Makefile b/lib/librte_kni/Makefile > >>>>> index 7107832..895f64e 100644 > >>>>> --- a/lib/librte_kni/Makefile > >>>>> +++ b/lib/librte_kni/Makefile > >>>>> @@ -34,7 +34,7 @@ include $(RTE_SDK)/mk/rte.vars.mk > >>>>> # library name > >>>>> LIB =3D librte_kni.a > >>>>> > >>>>> -CFLAGS +=3D $(WERROR_FLAGS) -I$(SRCDIR) -O3 -fno-strict-aliasing > >>>>> +CFLAGS +=3D $(WERROR_FLAGS) -I$(SRCDIR) $(CONFIG_RTE_LIBRTE_KNI_CF= LAGS) > >>>>> > >>>>> EXPORT_MAP :=3D rte_kni_version.map > >>>>> > >>>>> diff --git a/mk/rte.app.mk b/mk/rte.app.mk > >>>>> index 63a41e2..eee477d 100644 > >>>>> --- a/mk/rte.app.mk > >>>>> +++ b/mk/rte.app.mk > >>>>> @@ -78,6 +78,13 @@ endif > >>>>> ifeq ($(CONFIG_RTE_LIBRTE_KNI),y) > >>>>> ifeq ($(CONFIG_RTE_EXEC_ENV_LINUXAPP),y) > >>>>> LDLIBS +=3D -lrte_kni > >>>>> + > >>>>> +ifeq ($(CONFIG_RTE_LIBRTE_KNI_DEBUG),y) > >>>>> +CONFIG_RTE_LIBRTE_KNI_CFLAGS =3D -O0 -g -fno-strict-aliasing -fno-= inline > >>>>> +else > >>>>> +CONFIG_RTE_LIBRTE_KNI_CFLAGS =3D -O3 -fno-strict-aliasing > >>>>> +endif > >>>>> + > >>>>> endif > >>>>> endif > >>>>> > >>>>> > >>>>> Thoughts? > >>>> My 5c is that if anything, DPDK needs *less* places that muck around= with > >>>> compiler flags, not more. If you something like this for all the lib= raries > >>>> in DPDK the number doesn't just increase a bit, it explodes. > >>> If you check the part below this one in my original email, that you s= tripped > >>> out (without notice), the suggestion was also to add a global _DEBUG > >>> parameter for the entire DPDK set of libraries, to change all the CFL= AGS at > >>> once (not in the attached PATCH). > >>> > >>>> I dont see that much point in this thing, but I'd approach it by def= ining > >>>> the debug flags someplace central, say DEBUG_FLAGS, and append that = to the > >>>> common cflags when *_DEBUG config is enabled. At least with gcc the = last > >>>> option wins so if you just append -O0 when debugging then that's wha= t > >>>> wins, the earlier -O3 does not matter. > >>> The original problem is the one you expose; libraries hardcode the CF= LAGS, > >>> ignoring user-flags. There is no way to change this unless you change= the > >>> Makefiles directly. > >>> > >>> But right now, each library does hardcode its *own* flags (check Make= files > >>> for the libraries), so there is already not a unified approach here. = I see > >>> for instance KNI having -fno-strict-aliasing while other libraries do= n't. > >>> > >>> Having said that, there are moments, specially with -O3, in which to = be able > >>> to reproduce a bug, you need to compile certain parts of code with -O= 3 and > >>> the rest with -O0 -g (the ones to be debugged). The approach proposed= (both > >>> a global *and* a lib specific) allows that. > >>> > >>> Marc > >>> > >> I believe that the global option of overriding the CFLAGS is already s= ufficiently > >> covered - including being documented in programmers guide - by EXTRA_C= FLAGS. The > >> ability to turn off optimization support for a single library is not c= overed > >> anywhere, and that suggestion seems reasonable to me. For each library= , we can > >> just append '-O0 -g' to the CFLAGS in that libraries makefile if the d= ebug option > >> is set. I don't see that as significantly complicating things [though = I wouldn't > >> make any changes to the rte.app.mk to allow this, just have it per lib= in the > >> lib's makefile] > >> > > Well, but then people would say 'why only -g -O0' for _DEBUG config opt= ion? > > And would ask for ability to add/change other compile options to add/ch= ange for particular library. > > If we need that, probably we can introduce RTE_LIBRTE_<LIBNAME>_EXTRA_C= FLAGS config macros for each library? > > So people can set them in their config files to whatever they like? >=20 > It is not a bad idea either. However, there are already those _DEBUG > config elements (the KNI is a special case). >=20 > Maybe both can be combined (i.e. RTE_LIBRTE_<LIBNAME>_EXTRA_CFLAGS > should always override _DEBUG). It would probably get a bit > over-engineered then, though. I would probably leave _DEBUG config options with what they are doing right= now: perform extra checks and generate logs. After all, people might want their program to be more verbose, but they don= 't want compile options to be changed. =20 Konstantin >=20 > marc > > > > Konstantin