Path: utzoo!attcan!uunet!pyrdc!pyrnj!rutgers!cs.utexas.edu!ico!dougm
From: dougm@ico.ISC.COM (Doug McCallum)
Newsgroups: comp.emacs
Subject: Re: Possible to do #undef NO_REMAP for V/386?
Keywords: 386,NO_REMAP
Message-ID: <11091@ico.ISC.COM>
Date: 17 Nov 88 00:50:06 GMT
References: <442@arisia.Xerox.COM>
Reply-To: dougm@ico.ISC.COM (Doug McCallum)
Organization: Interactive Systems Corp., Boulder CO
Lines: 25

In article <442@arisia.Xerox.COM> weikart@arisia.Xerox.COM (Scott Weikart) writes:
...
>I'm using GNU Emacs 18.52 on a 386/AT clone, with MicroPort Unix and Everex's
>Enix (both derived from AT&T V/386, System 5 Release 3.0).  Has anyone been
>able to successfully dump a GNU Emacs with the read-only data region remapped
>into the text region, i.e. with #undef NO_REMAP ?  I got the following comment
>on this:
...
>Also, it has been suggested that #undef NO_REMAP isn't as important with
>System V release 3, because under Vr3 a new exec shares an existing data
>region, and uses copy on write to replace the data region pages that get
>changed, so that in general there is only one copy of the Emacs libraries in
>memory even if there are multiple Emacses running.  Is this correct?

On a standard V.3 paging system the the data segment is copy-on-write
and it should be that way on the 386 system you have, it is on mine.
Also, 386 memory regions are at 4 megabyte boundaries.  That is, data
in emacs starts at 4 meg so trying to push it into text would require
some creative use of the load file option of ld.  The amount of extra
work wasn't worth it when I first did 386 support in GNU so I didn't
do it and apparently no one has since.

Hope this helps,
Doug McCallum
dougm@ico.isc.com