From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wg0-f51.google.com (mail-wg0-f51.google.com [74.125.82.51]) by dpdk.org (Postfix) with ESMTP id C29E1C310 for ; Tue, 14 Apr 2015 16:17:47 +0200 (CEST) Received: by wgyo15 with SMTP id o15so13712615wgy.2 for ; Tue, 14 Apr 2015 07:17:47 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:organization :user-agent:in-reply-to:references:mime-version :content-transfer-encoding:content-type; bh=tGbcIrcWmGSif0fHn46CmO/+6EVlDmYpLhOyui8wPV4=; b=Q8G/i7JUvgSfr7SalsvUk3nCDHsjfQPjRv8dRpzwe5L+kcKLmxzS7dS1a/d3iNLdyE OSGm0I3Uyj0pGtJO41kUFMb8UJU9f6DcHuIMZ+kMMCFLunUy8+U7w2Inuzn2bjeOF37a VIoQ7w8yOKcNe2tJr/8hdw24LTZVqXTQ+ZB9jYRdu6sTZAv5Qgn+BdVD9VnUqK+XP1rG Q0r6F8fYitcTopaCnLEVuOs97/BcKgTL4z05R3Ood+ifaBXq7Tqf0SAlD0yRnZ6pfIbb AOCJeNxw1rU2AEyjrlvgMf4YKteb/x12TKoic9LjUqyU8+iOeadL6zZc80Ld9hctwEuO Jbow== X-Gm-Message-State: ALoCoQkg+mjacLWRHYBSIJnyQtnTrc4U2eSRtKWE0okO8p5HMH4j6e/d58UvVDgVmni32wB/5l1A X-Received: by 10.194.185.9 with SMTP id ey9mr40509646wjc.135.1429021066624; Tue, 14 Apr 2015 07:17:46 -0700 (PDT) Received: from xps13.localnet (136-92-190-109.dsl.ovh.fr. [109.190.92.136]) by mx.google.com with ESMTPSA id eu3sm1782534wjb.16.2015.04.14.07.17.45 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 14 Apr 2015 07:17:45 -0700 (PDT) From: Thomas Monjalon To: Vlad Zolotarov Date: Tue, 14 Apr 2015 16:17:04 +0200 Message-ID: <54963304.brPH8sEe9A@xps13> Organization: 6WIND User-Agent: KMail/4.14.4 (Linux/3.18.4-1-ARCH; KDE/4.14.4; x86_64; ; ) In-Reply-To: <552D1869.4060703@cloudius-systems.com> References: <1429003900-20074-1-git-send-email-thomas.monjalon@6wind.com> <2601191342CEEE43887BDE71AB9772582141570C@irsmsx105.ger.corp.intel.com> <552D1869.4060703@cloudius-systems.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Cc: dev@dpdk.org Subject: Re: [dpdk-dev] [PATCH] ixgbe: fix build with gcc 4.4 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: Tue, 14 Apr 2015 14:17:48 -0000 2015-04-14 16:38, Vlad Zolotarov: > On 04/14/15 16:06, Ananyev, Konstantin wrote: > > From: Vlad Zolotarov [mailto:vladz@cloudius-systems.com] > >> On 04/14/15 12:31, Thomas Monjalon wrote: > >>> - struct rte_eth_dev_info dev_info = { 0 }; > >>> + struct rte_eth_dev_info dev_info = { .max_rx_queues = 0 }; > >> > >> Hmmm... Unless I miss something this and one above would zero only a > >> single field - "max_rx_queues"; and would leave the rest uninitialized. > >> The original code intend to zero the whole struct. The alternative to > >> the original lines could be usage of memset(). > > > > As I understand, in that case compiler had to set all non-explicitly initialised members to 0. > > So I think we are ok here. > > Yeah, I guess it does zero-initializes the rest > (https://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html) however I > don't understand how the above change fixes the error if it complains > about the dev_info.driver_name? As only 1 field is required, I chose the one which should not be removed from this structure in the future. > What I'm trying to say - the proposed fix is completely unclear and > confusing. Think of somebody reading this line in a month from today - > he wouldn't get a clue why is it there, why to explicitly set > max_rx_queues to zero and leave the rest be zeroed automatically... Why > to add such artifacts to the code instead of just zeroing the struct > with a memset() and putting a good clear comment above it explaining why > we use a memset() and not and initializer? We can make it longer yes. I think you agree we should avoid extra lines if not needed. In this case, when reading "= { .field = 0 }", it seems clear our goal is to zero the structure (it is to me). I thought it is a basic C practice. You should try "git grep '\.[^ ]\+ *= *0 *}'" to be convinced that we are not going to comment each occurence of this coding style. But it must be explained in the coding style document. Agree?