Path: utzoo!attcan!uunet!lll-winken!ames!oliveb!sun!pepper!cmcmanis
From: cmcmanis%pepper@Sun.COM (Chuck McManis)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Task KILL for Amiga
Message-ID: <87289@sun.uucp>
Date: 27 Jan 89 18:46:55 GMT
References: <8901251704.AA18073@terra.oscs.montana.edu> <5799@cbmvax.UUCP> <5808@cbmvax.UUCP> <5813@cbmvax.UUCP>
Sender: news@sun.uucp
Reply-To: cmcmanis@sun.UUCP (Chuck McManis)
Organization: Sun Microsystems, Mountain View
Lines: 21

In the referenced articles Randell and Michael were debating where one
might want to truely use the MEMF_PUBLIC flag. Generally, in the Amiga
MEMF_PUBLIC has little or no use. What they seem to be overlooking is
that there is a large degree of difference between tasks/processes and
"context". In the future version of "Exec" that extends control to an
MMU based system, what will be important is what "context" the task is
running in, rather than what task the pc happens to be sitting in. 
Essentially, some tasks such as handlers and I/O devices share the 
same context as all of their client tasks. So when you go to Examine
a file or read the joystick the message you pass remains in your context
(and hence your address space) and thus the other task has no problem
reading or writing it. When a reply is sent, the context is established
first so that you can be sure the reply will go to the correct place.
Think of the Amiga as operating in a single context today. Tomorrow, 
that context information may be changed on the fly but the programs
will still work.


--Chuck McManis
uucp: {anywhere}!sun!cmcmanis   BIX: cmcmanis  ARPAnet: cmcmanis@sun.com
These opinions are my own and no one elses, but you knew that didn't you.