Path: utzoo!attcan!uunet!lll-winken!lll-tis!ames!mailrus!tut.cis.ohio-state.edu!osu-cis!att!chinet!mcdchg!nud!fishpond!fnf
From: fnf@fishpond.UUCP (Fred Fish)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Address Space on the Amiga (was Re: Need info on exceptions)
Message-ID: <127@fishpond.UUCP>
Date: 1 Sep 88 16:49:43 GMT
References: <8808311759.AA19249@cory.Berkeley.EDU>
Reply-To: fnf@fishpond.UUCP (Fred Fish)
Organization: occasionally
Lines: 31

In article <8808311759.AA19249@cory.Berkeley.EDU> dillon@CORY.BERKELEY.EDU (Matt Dillon) writes:
>	Then we get to keep our IPC message-pointer passing model and go FAST
>PLUS HAVE MEMORY PROTECTION all at the same time.

In my original comment on this subject it might appear that I was against
the "all addresses are physical addresses" concept, which I certainly am
not.  What I want, and absolutely require in any future machine I buy for
serious purposes (I.E. use to generate income to put a roof over my head
and food on the table), is:

	Support for interprocess memory protection that is hardware
	based (cannot be subverted by runaway processes as some
	software implementations can).  I can allow or disallow
	access to any range of addresses that I desire, modulo
	certain alignment and size restrictions.  Thus I can have
	totally private code or data space and shared code or data
	space for which any combination of read, write, or execute
	permissions can be granted.  Thus I can keep others from
	mucking around in my data structures, and build "pits"
	into which other processes can dump whatever data they want,
	that I can use cautiously after looking it over carefully.

Other than this, I only mentioned virtual memory because the hardware used
to provide memory protection is commonly powerful enough to also permit
virtual memory.  The virtual memory could be done at a level "below" that
of every process, so that it simply appeared to most of the kernel and
to all processes that you had an unlimited amount of physical memory.

-Fred
-- 
# Fred Fish, 1346 West 10th Place, Tempe, AZ 85281,  USA
# noao!nud!fishpond!fnf                   (602) 921-1113