From owner-cvs-src@FreeBSD.ORG Fri Oct 26 16:37:59 2007 Return-Path: Delivered-To: cvs-src@FreeBSD.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 2C87F16A468; Fri, 26 Oct 2007 16:37:59 +0000 (UTC) (envelope-from scottl@samsco.org) Received: from pooker.samsco.org (pooker.samsco.org [168.103.85.57]) by mx1.freebsd.org (Postfix) with ESMTP id CC98813C4BC; Fri, 26 Oct 2007 16:37:58 +0000 (UTC) (envelope-from scottl@samsco.org) Received: from phobos.samsco.home (phobos.samsco.home [192.168.254.11]) (authenticated bits=0) by pooker.samsco.org (8.13.8/8.13.8) with ESMTP id l9QGbftx069768; Fri, 26 Oct 2007 10:37:42 -0600 (MDT) (envelope-from scottl@samsco.org) Message-ID: <472217C2.8020800@samsco.org> Date: Fri, 26 Oct 2007 10:37:22 -0600 From: Scott Long User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X; en-US; rv:1.8.1.6) Gecko/20070802 SeaMonkey/1.1.4 MIME-Version: 1.0 To: John Baldwin References: <200710150951.l9F9pUm7026506@repoman.freebsd.org> <20071025233536.B99770@fledge.watson.org> <472120E8.90504@samsco.org> <200710261144.34645.jhb@freebsd.org> In-Reply-To: <200710261144.34645.jhb@freebsd.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH authentication, not delayed by milter-greylist-2.0.2 (pooker.samsco.org [168.103.85.57]); Fri, 26 Oct 2007 10:37:42 -0600 (MDT) X-Spam-Status: No, score=-1.4 required=5.5 tests=ALL_TRUSTED autolearn=failed version=3.1.8 X-Spam-Checker-Version: SpamAssassin 3.1.8 (2007-02-13) on pooker.samsco.org Cc: src-committers@FreeBSD.org, d@delphij.net, Andrey Chernov , cvs-all@FreeBSD.org, Robert Watson , cvs-src@FreeBSD.org Subject: Re: cvs commit: src/lib/libc/locale utf8.c X-BeenThere: cvs-src@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: CVS commit messages for the src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 26 Oct 2007 16:37:59 -0000 John Baldwin wrote: > On Thursday 25 October 2007 07:04:08 pm Scott Long wrote: >> Robert Watson wrote: >>> On Thu, 25 Oct 2007, Andrey Chernov wrote: >>> >>>> On Thu, Oct 25, 2007 at 12:05:40PM -0700, LI Xin wrote: >>>>> Well, I think the problem is not exposing a new symbol by itself, but >>>>> __mb_sb_limit is being used in _ctype.h, in a form of __inline >>>>> functions. Therefore, the change will break new binaries running on >>>>> older systems. >>>> Yes. Only vice versa compatibility supported. >>> I think the issue here is that the change occurred very quickly after >>> the branch, and when users wanted to 'change gears' back to RELENG_7 >>> from HEAD once it was created immediately ran into the problem. It >>> seems like a useful piece of post-branch advice to developers in the >>> future will be, "Please don't do things that make switching branches -- >>> back or forward -- for the first few weeks after the branch is >>> created". In general, I don't think we care about forward >>> compatibility, but we are currently getting lots of reports because this >>> is one of those few times where a lot of moving backward happens. >>> >> We do care about forward compatibility within STABLE branches, as Ken >> and I have discussed in side threads. But yes, forward compat between >> major branches is merely desired; i.e. changes will happen, and >> hopefully not for gratuitous reasons. > > If we care about forward compatiblity then we can't add new features to > RELENG_X branches. For example, MFCing MSI to 6.x broke forward compat since > a 6.3 module might call the MSI methods thus can't be used on a 6.2 kernel. > AFAIK, we have _never_ promised anything wrt forward compat, only backwards > ABI compat. I can agree with Robert above that during a transition time such > as now it's really handy to be able to switch easily between branches, but I > didn't think it was ever a concern otherwise. If we are going to change the > policy for that then there's a whole bunch of crap I need to go back out of > 6.x to restore compat. :-/ > You're right that nothing can be promised, but you're ignoring what Ken and I are saying about having a justification for changes. Yes, MSI added a feature that wasn't present in previous releases. But it's something that is optional and can be easily ifdef'd in source. The ctype ABI change isn't like that at all; it's mandatory and it can't be worked around. We also asked that even justifiable changes be evaluated to see if there was any work-around to avoid breakage. Several have already been suggested for the ctype change. Scott