From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id BF0DCA0547 for ; Mon, 19 Jul 2021 10:38:23 +0200 (CEST) Received: from [217.70.189.124] (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id B637B410FC; Mon, 19 Jul 2021 10:38:23 +0200 (CEST) Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by mails.dpdk.org (Postfix) with ESMTP id F030D4068B; Mon, 19 Jul 2021 10:38:20 +0200 (CEST) X-IronPort-AV: E=McAfee;i="6200,9189,10049"; a="209113475" X-IronPort-AV: E=Sophos;i="5.84,251,1620716400"; d="scan'208";a="209113475" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Jul 2021 01:38:20 -0700 X-IronPort-AV: E=Sophos;i="5.84,251,1620716400"; d="scan'208";a="430695884" Received: from bricha3-mobl.ger.corp.intel.com ([10.252.28.84]) by fmsmga007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-SHA; 19 Jul 2021 01:38:18 -0700 Date: Mon, 19 Jul 2021 09:38:14 +0100 From: Bruce Richardson To: Liang Ma Cc: Stephen Hemminger , dev@dpdk.org, leyi.rong@intel.com, Liang Ma , stable@dpdk.org, Konstantin Ananyev Message-ID: References: <20210717170830.1736-1-liangma@liangbit.com> <20210717104849.2ec6526e@hermes.local> <20210717221304.GA45@DESKTOP-POQV63C.localdomain> <20210717180804.301f7876@hermes.local> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [dpdk-stable] [dpdk-dev] [PATCH] buildtools: Check GCC version to avoid GCC 6.3.0 avx512 bug X-BeenThere: stable@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: patches for DPDK stable branches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: stable-bounces@dpdk.org Sender: "stable" On Sun, Jul 18, 2021 at 10:33:15AM +0100, Liang Ma wrote: > On Sat, Jul 17, 2021 at 06:08:04PM -0700, Stephen Hemminger wrote: > > On Sat, 17 Jul 2021 23:13:04 +0100 > > Liang Ma wrote: > > > > > On Sat, Jul 17, 2021 at 10:48:49AM -0700, Stephen Hemminger wrote: > > > > On Sat, 17 Jul 2021 18:08:30 +0100 > > > > Liang Ma wrote: > > > > > > > > > From: Liang Ma > > > > > > > > > > GCC 6.3.0 has a known bug which related to _mm512_extracti64x4_epi64. > > > > > Please reference https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82887 > > > > > > > > > > Some DPDK PMD avx512 version heavily use _mm512_extracti64x4_epi6, > > > > > which casue building failure with debug buildtype. > > > > > > > > > > Therefore, it's helpful to disable avx512 for GCC 6.3.0 > > > > > > > > > > Bugzilla ID: 717 > > > > > Fixes: e6a6a138919f (net/i40e: add AVX512 vector path) > > > > > Fixes: 808a17b3c1e6 (net/ice: add Rx AVX512 offload path) > > > > > Fixes: 4b64ccb328c9 (net/iavf: fix VLAN extraction in AVX512 path) > > > > > Cc: stable@dpdk.org > > > > > > > > > > Reported-by: Liang Ma > > > > > Signed-off-by: Liang Ma > > > > > > > > What distro still has GCC 6.3.0? > > > For example Debian 9.x > > > > Ok, thanks. Is there a bug fix in Debian LTS yet? > I look into https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82887, and > find gcc community has no plan to backport fix. Hence, I don't think > Debian LTS will have any fix for this. That's why I send out this patch. > Thanks for the report. However, rather than just disabling based on version number, can we instead use a compile-time check for broken compiler. This is what we did previously for other similar issues and it works better because: * removes the possibility of us missing a broken compiler version * takes account of the possibility of a fix backport (even if we don't expect one, it's best not to count it out) Looking at the bug report, it seems this issue could be detected directly in meson using "cc.compiles" and the code snippet from the report. Regards, /Bruce