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From: pl@etana.tut.fi (Lehtinen Pertti)
Newsgroups: comp.sys.amiga.tech
Subject: Re: MMU + A3000 + AmigaOS2.0 == Non-crashing system?
Message-ID: <1990Aug1.092303.19256@funet.fi>
Date: 1 Aug 90 09:23:03 GMT
References: <2489@clinet.FI>
Sender: news@funet.fi (#News )
Organization: Finnish University and Research Network FUNET
Lines: 48


From article <2489@clinet.FI>, by dix@clinet.FI (Risto Kaivola):
> 
> 	I have read comp.sys.amiga.xxxx groups and seen plenty of
> information about the new Amiga operating system version 2.0. I've
> probably missed something, because I don't know does the OS2.0 use the
> MMU to prevent those nasty Gurus. Therefore, I have the following
> questions:
> 
> 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?
>

	AmigaDOS message passing mechanism is based on pointer passing,
	which means that communicating processes must have shared dataspace.
	And I afraid that there exists programs, which don't allocate
	their messages with MEMF_PUBLIC flag on, but instead use their
	stack or even code segment. And that means that even these can't
	be protected.

> 
> 2)If the OS2.0 supports the MMU (I'd really like it to happen) will this
> cause any compatibility problems with the older versions of the OS?
>

	I afraid so.

> 
> 3)If the OS2.0 doesn't support the MMU, is it because the UNIX version
> for the amiga (in the distant future) will?
> 

	These are totally unrelated things, actions of some future
	UNIX don't affect OS2.0 in any way.

>
> 4)Are there some hardware related things that could prevent me using the
> MMU while bypassing the OS?
>

	If you are bypassing OS, nothing could prevent anything from you.
	OS uses MMU to protect itself from bypassing.

--
pl@tut.fi				! All opinions expressed above are
Pertti Lehtinen				! purely offending and in subject
Tampere University of Technology	! to change without any further
Software Systems Laboratory		! notice