*BSD News Article 5253


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Newsgroups: comp.unix.bsd
Path: sserve!manuel!munnari.oz.au!uunet!mcsun!sun4nl!fwi.uva.nl!casper
From: casper@fwi.uva.nl (Casper H.S. Dik)
Subject: Re: Shared Libs for X11?, was Re: 386bsd -- The New Newsgroup
Message-ID: <1992Sep18.154723.29222@fwi.uva.nl>
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References: <veit.716291291@du9ds3>> <1992Sep14.232949.9093@bby.com.au> 	<2aFn02vQ22Jx01@JUTS.ccc.amdahl.com> <Buo74w.Jp2@pix.com> <JP107.92Sep18105432@grus.cus.cam.ac.uk>
Date: Fri, 18 Sep 1992 15:47:23 GMT
Lines: 29

jp107@cus.cam.ac.uk (Jon Peatfield) writes:

>In <Buo74w.Jp2@pix.com> stripes@pix.com (Josh Osborne) correctly states:
>> Runtime linked code will not allways be the same for each copy of the
>> same executable.  Not if we support a library path like Sun does (which
>> is a good idea), or if a new lib is installed after starting one copy of
>> xterm but before another is started.

>But, by being careful one can arrange to keep all the parts of the
>program which must be modified in the data segment of the program,
>thus allowing the text segment to remain shared and unmodified after
>final linkage.  Thus while the data segment is a bit bigger, and
>unsharable most of the program is sharable and can be loaded r/o into
>memory.

Which is what Sun intended. However, the rules of building shared libraries
on Suns were never totally enforced by the ld, when used with its
default options. If ``-assert pure-text'' had been used by all
shared library builders when linking their test programs, there
wouldn't have been so many problems. Although, building a shared library
on Suns might have proven to be too difficult for many.

I believe Solaris 2.0 has made building shared libraries a lot easier,
probably made possible because Solaris 2.0 no longer uses a.out.

Casper
-- 
						|	Casper H.S. Dik
						|	casper@fwi.uva.nl