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From: jdp@caleb.UUCP (Jim Pritchett)
Newsgroups: comp.sys.amiga.tech
Subject: Memory Protection
Message-ID: <7955.AA7955@caleb>
Date: 7 Mar 90 01:36:51 GMT
Followup-To: comp.sys.amiga.tech
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I have an idea for memory protection for the Amiga OS.  Step 1:  assume
MMU.  Step 2:  all memory shared between multiple processes (i.e. OS
stuff, messages, etc.) can only be written by an OS server process.
When a user level process wants to write to shared memory, it asks
the OS server to do so.  Any errant process trying to scribble outside
of its area would cause the MMU to generate an error.  Is this reasonable?
Basically, let anyone read anywhere they want (i.e. in the specially
mapped shared area), but the MMU is used to prevent any user task from
writing there.  This would be slower than now (MMU waits + server time)
but I think that it could be made to work.

Before you flame me, please remember that I am NOT an expert here.  This
is basically just a response to all the "memory protection is impossible
with the Amiga OS" posts.  I am curious as to why this would not be
feasible.  (Of course, I am suggesting a very major change to the OS
here.)




--

                                                Jim Pritchett


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