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From: guy@sun.uucp (Guy Harris)
Newsgroups: net.emacs
Subject: Re: Including the "-n" ld option on BSD 4.2
Message-ID: <8505@sun.uucp>
Date: Fri, 24-Oct-86 15:05:21 EDT
Article-I.D.: sun.8505
Posted: Fri Oct 24 15:05:21 1986
Date-Received: Sun, 26-Oct-86 01:50:44 EDT
References: <3574@mit-eddie.MIT.EDU>
Organization: Sun Microsystems, Inc.
Lines: 24

>         Is there a reason why temacs is not loaded with the "-n"
>         flag on BSD 4.2 systems?  It would seem to be a reasonable thing
>         to do

Yes, there is a reason, namely that it is *not* a reasonable thing to do.
Loading with the "-n" flag builds an executable image that must be loaded
*all at once* when you "exec" it; both the Gosling/Unipress and GNU forms of
EMACS are BMF programs, and you may not want to load lots of pages of code
that you aren't going to use now or that you aren't going to use ever.

>	and the manual page does not indicate that "-n" is a default option.

To be precise, the manual page indicates that "-z" is the default option,
not "-n" (and definitely not "build an image with no shared text
whatsoever", as you were probably assuming).  "-z" "Arrange(s) for the
process to be loaded on demand from the resulting executable file (413
format) rather than preloaded."  This means that when the process takes a
page fault, if the page has not already been loaded and placed on the swap
device, it is loaded from the executable file.  You don't read in any code
unless you use it.
-- 
	Guy Harris
	{ihnp4, decvax, seismo, decwrl, ...}!sun!guy
	guy@sun.com (or guy@sun.arpa)