Path: utzoo!censor!geac!torsqnt!news-server.csri.toronto.edu!clyde.concordia.ca!thunder.mcrcim.mcgill.edu!snorkelwacker.mit.edu!apple!usc!wuarchive!uunet!isis!chanson
From: chanson@isis.cs.du.edu (Chris Hanson)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Help --> How to prevent the visit from the dreaded guru
Summary: Would this work?
Keywords: Exec, Messages, Protected memory, MMU, Hunks, Caffeine.
Message-ID: <1991Jan5.213642.16547@isis.cs.du.edu>
Date: 5 Jan 91 21:36:42 GMT
References: <611@caslon.cs.arizona.edu> <1991Jan4.224833.24914@ncsuvx.ncsu.edu> <17130@cbmvax.commodore.com>
Reply-To: chanson@isis.UUCP (Chris Hanson)
Organization: Matrix
Lines: 43

In article <17130@cbmvax.commodore.com> jesup@cbmvax.commodore.com (Randell Jesup) writes:
>	Correct.  First of all, 80-90% of all Amigas do not have an MMU, and
>aren't likely too (though maybe eventually - nowhere near soon - low-end
>machines may have MMUs).  Also, using protected-process-techniques for 
>inter-process communication would slow down the OS a lot (unacceptably so
>on a 68000 machine).  They add a lot of overhead, and add it even when there's
>no MMU in the system.  Witness the Bill Gates comments that multitasking will
>require 4Meg, a 386, and your first-born son.

  Couldn't you just make all inter-process communication be done using
MEMF_PUBLIC memory? As it was supposed to be? Since most people didn't do
this, Maybe make all the Message functions automagically force the
exchanged memory to be MEMF_PUBLIC temporarily. It'd be a pain, and a
megakludge, but it might work.

  As for Bill Gates: Did anyone else notice the InfoWorld Christmas-list
column, wherein they suggested that he wants a Video Toaster for Christmas,
to produce his next "IBM/Microsoft invented/is-leading-the-market-in
multimedia" video?

>	AmigaDos isn't likely to support protection any time soon - it's not
>designed for it, and attempting to add it would break almost any program that
>uses anything more complex than Dos functions (tty-style).  This may be a
>(very slight) exaggeration, but it's mostly true.  VM is far easier.

  Agreed, adding protection might break large quantities of stuff. How
about some kind of retrofit? Create a new object file hunk, say HUNK_FLAGS,
which tells you intimate info about the program that LoadSeg is bringing in.
You could have a flag to signify "I'm a nice program and I work well under
memory protection, so protect me if you can". This would also be an
excellent place to finally settle the PURE code problem. Make a hunk flag
that signifies, regardless of what the FS bit says, "This code is pure,
damnit." ;)

>Randell Jesup, Keeper of AmigaDos, Commodore Engineering.
>{uunet|rutgers}!cbmvax!jesup, jesup@cbmvax.commodore.com  BIX: rjesup  

   Chris - Xenon

-- 
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