From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by dpdk.org (Postfix) with ESMTP id C65C97EB0 for ; Wed, 3 Dec 2014 22:49:18 +0100 (CET) Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga101.fm.intel.com with ESMTP; 03 Dec 2014 11:46:22 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.07,508,1413270000"; d="scan'208";a="641838922" Received: from kmsmsx151.gar.corp.intel.com ([172.21.73.86]) by fmsmga002.fm.intel.com with ESMTP; 03 Dec 2014 06:00:07 -0800 Received: from shsmsx103.ccr.corp.intel.com (10.239.4.69) by KMSMSX151.gar.corp.intel.com (172.21.73.86) with Microsoft SMTP Server (TLS) id 14.3.195.1; Wed, 3 Dec 2014 22:00:06 +0800 Received: from shsmsx101.ccr.corp.intel.com ([169.254.1.110]) by SHSMSX103.ccr.corp.intel.com ([169.254.4.240]) with mapi id 14.03.0195.001; Wed, 3 Dec 2014 21:59:59 +0800 From: "Qiu, Michael" To: "Richardson, Bruce" , Michael Qiu Thread-Topic: [PATCH] test-pmd: Fix pointer aliasing error Thread-Index: AQHQDuxQX/2B2GdrV0OV5lPAliaykw== Date: Wed, 3 Dec 2014 13:59:58 +0000 Message-ID: <533710CFB86FA344BFBF2D6802E60286C9C531@SHSMSX101.ccr.corp.intel.com> References: <1417606044-3432-1-git-send-email-michael.qiu@intel.com> <1417606099-3489-1-git-send-email-michael.qiu@intel.com> <20141203114258.GA2396@bricha3-MOBL3> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.239.127.40] Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Cc: "dev@dpdk.org" Subject: Re: [dpdk-dev] [PATCH] test-pmd: Fix pointer aliasing error 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: Wed, 03 Dec 2014 21:49:19 -0000 On 2014/12/3 19:43, Richardson, Bruce wrote:=0A= > On Wed, Dec 03, 2014 at 07:28:19PM +0800, Michael Qiu wrote:=0A= >> app/test-pmd/csumonly.c: In function =91get_psd_sum=92:=0A= >> build/include/rte_ip.h:161: error: dereferencing pointer =91u16=92=0A= >> does break strict-aliasing rules=0A= >> build/include/rte_ip.h:157: note: initialized from here=0A= >> ...=0A= >>=0A= >> The root cause is that, compile enable strict aliasing by default,=0A= >> while in function rte_raw_cksum() try to convert 'const char *'=0A= >> to 'const uint16_t *'.=0A= >>=0A= > What compiler version is this with? Is there any other way to fix this=0A= > other than disabling the compiler warnings. Turning off strict aliasing m= ay=0A= > affect performance as it reduces the number of optimizations that the com= piler=0A= > can perform.=0A= =0A= The compile version is:=0A= =0A= $ gcc -v=0A= Using built-in specs.=0A= Target: x86_64-redhat-linux=0A= ...=0A= gcc version 4.4.7 20120313 (Red Hat 4.4.7-4) (GCC)=0A= =0A= =0A= The OS is centos6.5 x86_64=0A= =0A= =0A= Actually, another possible solution is, as gcc manual shows, use union.=0A= In function rte_raw_cksum() of lib/librte_net/rte_ip.h:=0A= =0A= static inline uint16_t=0A= rte_raw_cksum(const char *buf, size_t len){=0A= union {=0A= const char *ubuf;=0A= const uint16_t *uu16;=0A= } convert;=0A= =0A= convert.ubuf =3D buf;=0A= const uint16_t *u16 =3D convert.uu16;=0A= ...=0A= }=0A= =0A= This may be work, but not test yet.=0A= =0A= Any comments about this solution?=0A= =0A= Thanks,=0A= Michael=0A= >=0A= > /Bruce=0A= >=0A= >> Need to add CFLAG '-Wno-strict-aliasing' to avoid this issue.=0A= >>=0A= >> Signed-off-by: Michael Qiu =0A= >> ---=0A= >> app/test-pmd/Makefile | 2 +-=0A= >> 1 file changed, 1 insertion(+), 1 deletion(-)=0A= >>=0A= >> diff --git a/app/test-pmd/Makefile b/app/test-pmd/Makefile=0A= >> index 97dc2e6..995c874 100644=0A= >> --- a/app/test-pmd/Makefile=0A= >> +++ b/app/test-pmd/Makefile=0A= >> @@ -38,7 +38,7 @@ ifeq ($(CONFIG_RTE_TEST_PMD),y)=0A= >> #=0A= >> APP =3D testpmd=0A= >> =0A= >> -CFLAGS +=3D -O3=0A= >> +CFLAGS +=3D -O3 -Wno-strict-aliasing=0A= >> CFLAGS +=3D $(WERROR_FLAGS)=0A= >> =0A= >> ifeq ($(CONFIG_RTE_LIBRTE_PMD_PCAP),y)=0A= >> -- =0A= >> 1.9.3=0A= >>=0A= =0A=