From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?iso-8859-1?Q?N=E9lio?= Laranjeiro Subject: Re: [PATCH] net: introduce big and little endian types Date: Tue, 6 Dec 2016 14:14:17 +0100 Message-ID: <20161206131416.GR21794@autoinstall.dev.6wind.com> References: <2601191342CEEE43887BDE71AB9772583F0E3F68@irsmsx105.ger.corp.intel.com> <20161205120603.GL21794@autoinstall.dev.6wind.com> <2601191342CEEE43887BDE71AB9772583F0E4632@irsmsx105.ger.corp.intel.com> <20161206115502.GA12224@bricha3-MOBL3.ger.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Cc: "Ananyev, Konstantin" , "dev@dpdk.org" , Olivier Matz , "Lu, Wenzhuo" , Adrien Mazarguil To: Bruce Richardson Return-path: Received: from mail-wj0-f176.google.com (mail-wj0-f176.google.com [209.85.210.176]) by dpdk.org (Postfix) with ESMTP id 7D53A2BB3 for ; Tue, 6 Dec 2016 14:14:25 +0100 (CET) Received: by mail-wj0-f176.google.com with SMTP id tk12so25332623wjb.3 for ; Tue, 06 Dec 2016 05:14:25 -0800 (PST) Content-Disposition: inline In-Reply-To: <20161206115502.GA12224@bricha3-MOBL3.ger.corp.intel.com> List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" Hi Konstantin, Bruce, On Tue, Dec 06, 2016 at 11:55:02AM +0000, Bruce Richardson wrote: > On Tue, Dec 06, 2016 at 11:23:42AM +0000, Ananyev, Konstantin wrote: > > Hi Neilo, > > > > > > Hi Neilo, > > > > > > > > > > This commit introduces new rte_{le,be}{16,32,64}_t types and updates > > > > > rte_{le,be,cpu}_to_{le,be,cpu}_*() and network header structures > > > > > accordingly. > > > > > > > > > > Specific big/little endian types avoid uncertainty and conversion mistakes. > > > > > > > > > > No ABI change since these are simply typedefs to the original types. > > > > > > > > It seems like quite a lot of changes... > > > > Could you probably explain what will be the benefit in return? > > > > Konstantin > > > > > > Hi Konstantin, > > > > > > The benefit is to provide documented byte ordering for data types > > > software is manipulating to determine when network to CPU (or CPU to > > > network) conversion must be performed. > > > > Ok, but is it really worth it? > > User can still make a mistake and forget to call ntoh()/hton() at some particular place. > > From other side most people do know that network protocols headers are usually in BE format. > > I would understand the effort, if we'll have some sort of tool that would do some sort of static code analysis > > based on these special types or so. > > Again, does it mean that we should go and change uint32_t to rte_le_32 inside all Intel PMDs > > (and might be in some others too) to be consistent? > > Konstantin > > > > I actually quite like this patch as I think it will help make things > clear when the user is possibly doing something wrong. I don't think we > need to globally change all PMDs to use the types, though. I agree, at least APIs should use this, PMDs can do as they want. > One thing I'm wondering though, is if we might want to take this > further. For little endian environments, we could define the big endian > types as structs using typedefs, and similarly the le types on be > platforms, so that assigning from the non-native type to the native one > without a transformation function would cause a compiler error. > > /Bruce If I understand you correctly, this will break hton like functions which expects an uint*_t not a structure. -- Nélio Laranjeiro 6WIND