Date: Fri, 23 Oct 2015 15:06:22 -0700 From: Conrad Meyer <cem@FreeBSD.org> To: Ian Lepore <ian@freebsd.org> Cc: "svn-src-head@freebsd.org" <svn-src-head@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, "src-committers@freebsd.org" <src-committers@freebsd.org> Subject: Re: svn commit: r289773 - in head: sbin/sysctl sys/kern sys/sys Message-ID: <CAG6CVpVNuZQtkZhbuKPTzBG7PfyXiDu4Aav5-d2dgaQWEw2x0A@mail.gmail.com> In-Reply-To: <1445637372.91534.38.camel@freebsd.org> References: <201510222303.t9MN37D2093845@repo.freebsd.org> <CAGHfRMCSjzC5FCk9cd8At=Q%2BDtQkXvYVsq3tfQ_aMPSVLZpqnQ@mail.gmail.com> <CAG6CVpW6W%2BDu0kgmgUnbU1tyXOxZ54C7Op6wRX9=i9bhipH6qQ@mail.gmail.com> <20151023210604.GA12348@lonesome.com> <CAG6CVpU2ANjWBot=2OCqcu9zT=HrK=ubdJsYPCedyz8jL35=SQ@mail.gmail.com> <1445637372.91534.38.camel@freebsd.org>
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On Fri, Oct 23, 2015 at 2:56 PM, Ian Lepore <ian@freebsd.org> wrote: > On Fri, 2015-10-23 at 14:43 -0700, Conrad Meyer wrote: >> On Fri, Oct 23, 2015 at 2:06 PM, Mark Linimon <linimon@lonesome.com> >> wrote: >> > On Fri, Oct 23, 2015 at 08:09:35AM -0700, Conrad Meyer wrote: >> > > What is __FreeBSD_version and why would it be bumped? >> > >> > <stuff that does not inform what __FreeBSD_version is snipped> >> > >> > This variable exists to tell the Ports Collection, among others, >> > that "something has changed that may require you to patch and/or >> > recompile." > > Another is making it possible to test for new features that > arrived with a given version, and that's what you've done. > > Suppose I maintain an out-of-tree driver that has to build on several > versions, and uint16 is really the right type for its sysctl but it > also has to work on versions that don't have that support. That tends > to get handled with things like #if __FreeBSD_version < NNNNNNNN. > (Contrived example here maybe, since if uint32 worked on one version, > I'd likely use it on all of versions.) Suppose you did. The change lends itself to "#ifdef CTLTYPE_U16" =E2=80=94 = in this truly contrived scenario. Any other check is redundant or less specific. (As Ngie points out, checking an absolute version doesn't do you a lot of good in the face of backports/cherry-picks.) > One of the implications of the feature-availability testing is that > when you MFC your change, you also have to bump the version number on > that branch (independently, not via MFC). Not a problem =E2=80=94 the MFC After field was intentionally omitted (i.e.= , "MFC After: never"). This is only intended for CURRENT. Best, Conrad
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