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Path: euryale.cc.adfa.oz.au!newshost.carno.net.au!harbinger.cc.monash.edu.au!munnari.OZ.AU!news.Hawaii.Edu!ames!enews.sgi.com!news.sgi.com!howland.erols.net!feed1.news.erols.com!tipu2.cwix.net!uunet!in3.uu.net!199.170.214.67!trebuchet.va.pubnix.com!not-for-mail From: lidl@va.pubnix.com (Kurt J. Lidl) Newsgroups: comp.unix.bsd.bsdi.misc Subject: Re: BSDI 3.0 Impressive Date: 16 Mar 1997 21:49:55 -0500 Organization: UUNET Technologies -- Fairfax, Virginia, USA Lines: 39 Message-ID: <5gibgj$bu7@arrow.va.pubnix.com> References: <332849E6.71CA@cet.co.jp> <332824B1.6B5F@opengroup.org> <E6zpJB.Iv0@news.interactive.net> <5giab8$l8h@vanbc.wimsey.com> NNTP-Posting-Host: arrow.va.pubnix.com Xref: euryale.cc.adfa.oz.au comp.unix.bsd.bsdi.misc:6362 In <5giab8$l8h@vanbc.wimsey.com>, John Henders <jhenders@wimsey.com> wrote: >In <E6zpJB.Iv0@news.interactive.net>, <ritz@interactive.net> writes: > >>>Does it have shared libraries yet? > >>It's had shared libraries for years. Where have you been? >>I've been using them since the release of BSDI 2.1. > >Shared libraries came out with 2.0 actually. I believe the real question that should have been asked is, "Does it have dynamically linked libraries yet?", not "shared libraries". BSD/OS certainly has shared libraries, but doesn't have dynamically linked libraries, even in the 3.0 release. The difference? shared libraries --> multiple programs can share the same copy of the mapped text for libraries, resulting in very efficient use of memory space dynamically linked libraries --> each program's unresolved list of symbols is bound to a library symbol at run time. Under SunOS, this is done via an exec of the /usr/lib/ld.so program, which attempts to do this resolving by examining the list of libraries that was stored in the program. Normally, the list of libraries is the standard list of system libraries, which happen to be shared. One of the other restrictions of the BSDi scheme is that in the case of the shared libraries, they are mapped into the same virtual memory locations in each process. With most dynamic linking solutions, the processes don't have to map the shared libraries into the same virtual address locations. -Kurt -- /* Kurt J. Lidl (lidl@va.pubnix.com) UUCP: <Earth>!uunet!lidl */ /* Don't confuse my opinions with my employer's opinions! */ /* We may just have to destroy USENET, in order to save it. */