Date: Sun, 3 Feb 2008 08:59:45 -0700 From: "Peter Wemm" <peter@wemm.org> To: "=?ISO-8859-1?Q?Dag-Erling_Sm=F8rgrav?=" <des@des.no> Cc: threads@freebsd.org, current@freebsd.org Subject: Re: Symbol versioning errors in libthr Message-ID: <e7db6d980802030759x6db9bf1dq8992542bd8d2e017@mail.gmail.com> In-Reply-To: <861w7um5o5.fsf@ds4.des.no> References: <861w7um5o5.fsf@ds4.des.no>
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On Feb 3, 2008 8:16 AM, Dag-Erling Sm=F8rgrav <des@des.no> wrote: > Here's an excerpt from the RELENG_7 vs HEAD diff of libthr's symbol map: > > --- pthread.map 13 May 2007 14:12:39 -0000 1.18 > +++ pthread.map 20 Dec 2007 04:32:28 -0000 1.21 > @@ -84,9 +84,13 @@ > pthread_multi_np; > pthread_mutex_destroy; > pthread_mutex_getprioceiling; > + pthread_mutex_getspinloops_np; > + pthread_mutex_getyieldloops_np; > pthread_mutex_init; > pthread_mutex_lock; > pthread_mutex_setprioceiling; > + pthread_mutex_setspinloops_np; > + pthread_mutex_setyieldloops_np; > pthread_mutex_timedlock; > pthread_mutex_trylock; > pthread_mutex_unlock; > > These functions are all in FBSD_1.0, but they were introduced after the > branch and never MFCed, so if I understand how we've implemented symbol > versioning, they should be in FBSD_1.1. > > Unless someone argues credibly for keeping them in FBSD_1.0, I will move > them to FBSD_1.1 in a few days. > > DES I'm not sure I see the point in that. Consider the not-moving-to-1.1 case. If somebody takes an 8.0 binary and runs it on 7.x, then they'll get a 'symbol not found' error. On the other hand, if they're moved and somebody tries the same thing, then they still get the same kind of 'symbol not found' error but with just one character different. The point of symbol versioning is to allow incompatible changes. eg: to have a FBSD_1.0 version of pthread_mutex_getspinloops_np() *AND* a FBSD_1.1 version of pthread_mutex_getspinloops_np() in the library at the same time. The 1.0 instance would presumably be an API/ABI conversion wrapper around the newer functions. -Peter --=20 Peter Wemm - peter@wemm.org; peter@FreeBSD.org; peter@yahoo-inc.com "All of this is for nothing if we don't go to the stars" - JMS/B5
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