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From: mwm@eris.UUCP
Newsgroups: comp.sys.amiga,comp.sys.atari.st,comp.sys.m6809
Subject: Re: Re: True Multitasking, and shared code
Message-ID: <3934@jade.BERKELEY.EDU>
Date: Fri, 12-Jun-87 01:38:55 EDT
Article-I.D.: jade.3934
Posted: Fri Jun 12 01:38:55 1987
Date-Received: Sat, 13-Jun-87 11:31:28 EDT
References: <8706040024.AA10895@cogsci.berkeley.edu> <2194@husc6.UUCP> <1206@crash.CTS.COM>
Sender: usenet@jade.BERKELEY.EDU
Reply-To: mwm@eris.BERKELEY.EDU (Mike (My watch has windows) Meyer)
Organization: Missionaria Phonibalonica
Lines: 36
Keywords: shared text code libraries UNIX
Xref: utgpu comp.sys.amiga:5287 comp.sys.atari.st:3690 comp.sys.m6809:314

In article <1206@crash.CTS.COM> ford@crash.CTS.COM (Michael Ditto) writes:
<About shared text and libraries:  On the Amiga, the shared libraries are in
<the ROM -- they are the equivalent of system calls on UNIX.

Uh, that's a major oversimplification. It's better to say that the
equivalent of Unix system calls have been implemented as shared
libraries. The difference is that, as shared libraries, you can 1)
replace the library and 2) replace entries in a library. Try replacing
your Unix system calls without relinking the kernel.

<"libc" routines are still linked in with the executable and therefore exist
<multiple times, so AmigaDOS and UNIX are very similar in terms of memory
<usage.

Only in the C environment, where the Amiga has to do some extra work
to provide a Unix-like C environment. If you blow off the
Unix-compatable stuff and etc., AmigaDOS suddenly does much better.

<It is possible to write your own shared library, but it requires
<special programming techniques.  On UNIX System V release 3, this has been
<done, and there is a shared version of libc available; the supplied UNIX
<utilities have been compiled with it.  It is not the default because it is
<not possible to use most debugges on a program using a shared library.

Last time I looked (last year at the Atlanta Usenix), the SysV
libraries required root privs to install (DCL_SYS_ ... oops, sorry;
had a VMS flashback). This was because the memory allocation for
shared memory for a shared library had to be fixed. Ugh. Give me
AmigaDOS dynamic linking or OS/9 PIC anyday.

	<mike
--
How many times do you have to fall			Mike Meyer
While people stand there gawking?			mwm@berkeley.edu
How many times do you have to fall			ucbvax!mwm
Before you end up walking?				mwm@ucbjade.BITNET