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From: panon@cheddar.cc.ubc.ca (Paul-Andre Panon)
Newsgroups: comp.sys.amiga
Subject: Re: Memory protection for all amiga's
Message-ID: <7250@ubc-cs.UUCP>
Date: 21 Mar 90 03:40:02 GMT
References: <227.25ff6050@waikato.ac.nz> <532@bilver.UUCP>
Sender: news@cs.ubc.ca
Reply-To: panon@cheddar.cc.ubc.ca (Paul-Andre Panon)
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Organization: UBC Computing Centre, Vancouver, B.C., Canada
Lines: 23

In article <532@bilver.UUCP> alex@bilver.UUCP (Alex Matulich) writes:
>[blurb about message passing on the amiga]
>This means that the tasks in question must share
>the same address space.  An MMU would prohibit that.  An MMU causes each
>process to run in its own "aritifically-induced" address space, so a pointer
>from one process will not point to the same address as the same value of
>that pointer for another process.
This is incorrect as far as I know. Now certainly UNIX gives each process its
own virtual address space but that certainly isn't necessary for VM. All
processes could share the same map for VM->physical memory so that you could
still pass pointers. The problem is when you try to implement memory protection
that you can break things. For obvious reasons, you could only run VM on
FAST RAM, not CHIP (blitter wants this address. Just a second I'll page it in.
oops, there goes your screen, Sorry.)
>
>-- 
>     ///  Alex Matulich
P-A
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