Path: utzoo!utgpu!watmath!clyde!att!rutgers!mailrus!ames!pasteur!ucbvax!POSTGRES.BERKELEY.EDU!dillon
From: dillon@POSTGRES.BERKELEY.EDU (Matt Dillon)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Unsupported Programming Practices
Message-ID: <8901090852.AA22302@postgres.Berkeley.EDU>
Date: 9 Jan 89 08:52:33 GMT
Sender: usenet@ucbvax.BERKELEY.EDU
Lines: 43


	Linear address space, Linear address space, Linear address space.

	A Linear address space is the only possible way to switch to a MMU
environ without rewriting the entire OS from scratch.  At least that way the 
trillions upon trillions of memory violations that will occur for the first
3 years can be made non-lethal...  as in "warning this is wrong but it'll
still run" type of thing, whereas with a non-linear address space you will
be forced to 'kill the task'.  That isn't the only reason of course, but it's
pretty big.

				-Matt

:Now, down the future road, there is this dream of a protected task version
:of the Amiga OS.
:It seems clear to me that moving to protected tasks on an Amiga will be an
:evolutionary effort.  No existing program will work, I'd expect, so we'll need
:to find a way to support the existing programming model side-by-side with new,
:protected tasks.  At that time, there will be new rules and procedures for making
:protected tasks.  Things like AddTask() (instead of a system CreateTask()) will
:probably have to go, anyway, so there will probably be a whole new paradigm.
:
>If we are to move beyond protection into separate, overlapping logical
:address spaces for tasks, this whole "pointers to gadgets hanging off of
:windows" and "linked lists of menu items" business has to go, anyway.
:
:I strongly believe that a clear line should be drawn between practices which will
:break real soon and those, such as the traditional MEMF_PUBLIC lip service,
:which target some very long range, foggy future.

	MEMF_PUBLIC will have to go completely ... as in be ignored completely.
Create a new MEMF_ flag for the purpose after figure out the specific 
guidelines.  Again, with a linear address space you can make everything work.
Consider the difficulty of writing a library otherwise?  Consider even 
attempting to rewrite the OS?  It just won't happen with distinct address
spaces, too much code relies on the linearity and damn it!  It is a thousand
times easier to write things for a linear address space!

	(I'm trying to drill this into people now so it'll get implemented
this way because I just *KNOW* that if it doesn't the Amiga will go down the
tubes!)

			-Matt