From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.tuxdriver.com (charlotte.tuxdriver.com [70.61.120.58]) by dpdk.org (Postfix) with ESMTP id D18632C8 for ; Fri, 9 Mar 2018 01:19:47 +0100 (CET) Received: from cpe-2606-a000-111b-40b7-215-ff-fecc-4872.dyn6.twc.com ([2606:a000:111b:40b7:215:ff:fecc:4872] helo=localhost) by smtp.tuxdriver.com with esmtpsa (TLSv1:AES256-SHA:256) (Exim 4.63) (envelope-from ) id 1eu5kx-0003Im-73; Thu, 08 Mar 2018 19:19:39 -0500 Date: Thu, 8 Mar 2018 19:18:56 -0500 From: Neil Horman To: Thomas Monjalon Cc: Ferruh Yigit , John McNamara , Marko Kovacevic , dev@dpdk.org, Luca Boccassi , Christian Ehrhardt Message-ID: <20180309001856.GA9761@neilslaptop.think-freely.org> References: <20180307174422.118291-1-ferruh.yigit@intel.com> <4097404.y7j9CXhnSi@xps> <20180308194039.GB32578@hmswarspite.think-freely.org> <2251603.sn1Xas34Et@xps> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2251603.sn1Xas34Et@xps> User-Agent: Mutt/1.9.2 (2017-12-15) X-Spam-Score: -2.9 (--) X-Spam-Status: No Subject: Re: [dpdk-dev] [RFC] config: remove RTE_NEXT_ABI X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 09 Mar 2018 00:19:48 -0000 On Thu, Mar 08, 2018 at 10:34:14PM +0100, Thomas Monjalon wrote: > 08/03/2018 20:40, Neil Horman: > > On Thu, Mar 08, 2018 at 05:04:01PM +0100, Thomas Monjalon wrote: > > > 08/03/2018 16:35, Neil Horman: > > > > On Thu, Mar 08, 2018 at 04:17:00PM +0100, Thomas Monjalon wrote: > > > > > 08/03/2018 12:43, Ferruh Yigit: > > > > > > On 3/8/2018 8:05 AM, Thomas Monjalon wrote: > > > > > > > 07/03/2018 18:44, Ferruh Yigit: > > > > > > >> After experimental API process defined do we still need RTE_NEXT_ABI > > > > > > >> config and process which has similar targets? > > > > > > > > > > > > > > They are different targets. > > > > > > > Experimental API is always enabled but may be avoided by applications. > > > > > > > Next ABI can be used to break ABI without notice and disabled to keep > > > > > > > old ABI compatibility. It is almost never used because it is preferred > > > > > > > to keep ABI compatibility with rte_compat macros, or wait a deprecation > > > > > > > period after notice. > > > > > > > > > > > > OK, I see. > > > > > > > > > > > > Shouldn't we disable it by default at least? Otherwise who is not paying > > > > > > attention to this config option will get and ABI/API break. > > > > > > > > > > Yes I think you are right, it can be disabled by default. > > > > > > > > > I would agree, there seems to be overlap here, and the experimental tagging can > > > > cover what the NEXT_API flag is meant to do. It can be removed I think. > > > > > > It is not NEXT_API but NEXT_ABI. > > Sorry, typo, though I'm sure you got that, since the former doesn't exist, > > right? > > > Why do you think it overlaps experimental API tagging? > > > > I assert that because the compat lib has macros to map common symbols to version > > specific ones. That is to say, if you change a data structure, you can setup > > the API calls that use said structure such that version 1 or the symbol maps to > > an internal function that uses the old structure, while version 2 maps to an > > internal function that uses the new symbol > > > > That is to say, if you're planning on introducing ABI changes, the experimental > > API tagging can be used to implement what the NEXT_ABI macro does. > > It is a different usage. > Experimental API tagging is for new functions. > rte_compat is used to avoid breaking the ABI when changing old code. > NEXT_ABI has been used in the past to disable an ABI breakage, which was > not possible to mitigate with rte_compat because impacting too many functions. > Thats not entirely true. It _is_ used to manage ABI changes when backwards compatibiilty needs to be preserved. It _can_be_ used for experimental abi management. That is to say, if you want to modify an existing ABI symbol, you can do so by writing a new function, and then exporting the new function as the old symbol with the @EXPERIMENTAL version. Not saying we have to do that, but we certainly can, and can eliminate NEXT_ABI in the process. > I am not saying that I like NEXT_ABI, but it could be useful exceptionnally. > Well, if the consensus is that it should be kept, its no skin off my nose, but the discussion was around removing NEXT_ABI, and I was copied, so I thought I'd add my $0.02 Neil > >