From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Monjalon Subject: Re: [PATCH] ixgbe: fix build with gcc 4.4 Date: Tue, 14 Apr 2015 16:17:04 +0200 Message-ID: <54963304.brPH8sEe9A@xps13> 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-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Cc: dev-VfR2kkLFssw@public.gmane.org To: Vlad Zolotarov Return-path: In-Reply-To: <552D1869.4060703-RmZWMc9puTNJc61us3aD9laTQe2KTcn/@public.gmane.org> List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces-VfR2kkLFssw@public.gmane.org Sender: "dev" 2015-04-14 16:38, Vlad Zolotarov: > On 04/14/15 16:06, Ananyev, Konstantin wrote: > > From: Vlad Zolotarov [mailto:vladz-RmZWMc9puTNJc61us3aD9laTQe2KTcn/@public.gmane.org] > >> 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?