*BSD News Article 24012


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From: pk@cs.few.eur.nl (Paul Kranenburg)
Subject: Re: SUMMARY: FreeBSD vs. Linux
Message-ID: <1993Nov15.234441.6632@cs.few.eur.nl>
Sender: news@cs.few.eur.nl
Reply-To: pk@cs.few.eur.nl
Organization: Erasmus University Rotterdam
References: <2brq1b$a8j@news.ysu.edu> <CGC6nH.J08@usenet.ucs.indiana.edu> <2btv9t$4nb@news.cs.tulane.edu> <2bui0j$blb@fw.novatel.ca> <CGCroz.B6r@kithrup.com>
Date: Mon, 15 Nov 1993 23:44:41 GMT
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In <CGCroz.B6r@kithrup.com> sef@kithrup.com (Sean Eric Fagan) writes:

>Dynamicly-linked shared libraries were announced for testing for linux
>before they were announced for *bsd.  If I remember correctly, from looking
>at it, it was also less of a hack, and used ELF instead of a.out.  (Even
>COFF would be better than a.out for shared libraries, sheesh.)

ELF is certainly a more suitable format for doing shared libs (and other
things), but given the circumstances that the current generation of BSD
utilities still rely heavily on a.out, it would be asking for trouble to
try and convert them rashly. Also, kernel support will be required in
kern_exec.c to run ELF binaries.

Once we have some sound experience with building assemblers and linkers
proper (ie. the more-or-less format independent bits) we can turn our
attention to these other parts. Otherwise we'd end up debugging everything
at the same time.

While the use of a.out for dynamic linking can be construed as a hack, it's
not that *terrible* a hack. If you look carefully, the data structures used
are just an additional format embedded within the a.out sections. The
main drawback is that it's invisible to utilities like nm(1).

-pk
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