Date: Tue, 28 Aug 2007 06:38:57 +0400 From: Yar Tikhiy <yar@comp.chem.msu.su> To: Daniel Eischen <deischen@freebsd.org> Cc: src-committers@freebsd.org, John Baldwin <jhb@freebsd.org>, alfred@freebsd.org, cvs-all@freebsd.org, cvs-src@freebsd.org, "M. Warner Losh" <imp@bsdimp.com> Subject: Re: cvs commit: src/lib/libc/gen fts-compat.c fts-compat.h Message-ID: <20070828023857.GW21352@comp.chem.msu.su> In-Reply-To: <Pine.GSO.4.64.0708272127371.28508@sea.ntplx.net> References: <200708270850.20904.jhb@freebsd.org> <200708271715.21462.jhb@freebsd.org> <Pine.GSO.4.64.0708271719510.28508@sea.ntplx.net> <200708271757.01674.jhb@freebsd.org> <Pine.GSO.4.64.0708271757570.28508@sea.ntplx.net> <20070828004842.GT21352@comp.chem.msu.su> <Pine.GSO.4.64.0708272127371.28508@sea.ntplx.net>
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On Mon, Aug 27, 2007 at 09:30:48PM -0400, Daniel Eischen wrote: > On Tue, 28 Aug 2007, Yar Tikhiy wrote: > > > >Example: Assume we released 7.0-R with all symbols at FBSD_1.0. > >Before the 8.0 release cycle starts, struct FTS and struct FILE > >change, perhaps a few times each, thus affecting the fts(3) and > >stdio(3) global symbols. At the very first change to a symbol or > >their group, its 7.0-R variant is preserved at FBSD_1.0 and its > >default version becomes FBSD_1.1. Later changes to the current > >variant of that symbol don't affect its version. Consequently, > >8.0-R is released with the new fts(3) and stdio(3) symbols at > >FBSD_1.1, their 7.0-R variants at FBSD_1.0, and the rest of symbols > >still at FBSD_1.0 because they are unchanged. Let's note that > >CURRENT users had to rebuild ports depending on fts(3) or stdio(3) > >_each time_ an ABI component changed. > > I think you're a little confused here. CURRENT users did NOT have > to rebuild ports when fts(3) or stdio(3) ABIs changed. They > would only have to rebuild if one of these ABIs changed _more > than once between releases_. That hasn't ever happened to my > knowledge in the past, and it really shouldn't happen as long > as things are tested and reviewed properly. Oh, indeed! If a user builds an ABI-dependent port before the change, the port will record dependence on say fwrite@FBSD_1.0. In our example, the default version of fwrite() and friends will change to FBSD_1.1 later, after 7.0-RELEASE is out, but fwrite@FBSD_1.0 will also stay as a compatibility version because it appeared in the previous release. Moreover, the port will still work even if the ABI component changes once more after 8.0-RELEASE and proceeds to FBSD_1.2, because fwrite@FBSD_1.0 will be there. Similarly, a port built between 7.0-R and 8.0-R will work after the 2nd change as fwrite@FBSD_1.1 will be there, too. I can't but remark that this is not a natural effect of symbol versioning, but a consequence from the following policy: - At most one new version is introduced between major releases. - Symbol modifications during the period are assigned to the new version. - There is exactly one change per symbol per version. - All old symbol versions created so far are preserved. Now we have at least one policy with known behavior. :-) -- Yar
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