Path: utzoo!attcan!uunet!pyrdc!grebyn!ckp
From: ckp@grebyn.com (Checkpoint Technologies)
Newsgroups: comp.sys.amiga.tech
Subject: Re: MMU + A3000 + AmigaOS2.0 == Non-crashing system?
Message-ID: <20889@grebyn.com>
Date: 1 Aug 90 17:18:00 GMT
References: <2489@clinet.FI>
Reply-To: ckp@grebyn.UUCP (Checkpoint Technologies)
Organization: Grebyn Timesharing, Vienna, VA, USA
Lines: 27

In article <2489@clinet.FI> dix@clinet.FI (Risto Kaivola) writes:
>1)If the OS2.0 does not support the MMU upto the extent where all
>application programs could run independently, i.e not corrupting other
>programs' data, can you tell me what is the reason?
>

No, OS 2.0 does not use the MMU to protect applications from tromping on
each other's, or the systems, memory.  This is because there are so many
applications that share memory structures, and in the past these
applications have not been bound to inform the OS of their intentions.
When you don't tell the OS in advance what memory you're going to share,
then the OS cannot make any distinction between normal, healthy sharing,
and an unhealthy, amok program trouncing other applications.

Yes, there's been a lot of traffic in the comp.sys.amiga.xxx groups
about this.  Unfortunately, I haven't heard a workable solution for
existing applications, I can't think of one myself, and many net.folk
whose opinions I respect have claimed it can't be practically done.

Therefore, the way to get MMU protection for your applications is to
abandon application binary compatibility; and if you're going to do
this anyway, then why not just use Unix?
-- 
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