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From: cc1@locus.ucla.edu (Michael Gersten)
Newsgroups: net.micro.amiga
Subject: Re: An Idea for an ambitious programmer
Message-ID: <1993@curly.ucla-cs.ARPA>
Date: Wed, 8-Oct-86 14:46:00 EDT
Article-I.D.: curly.1993
Posted: Wed Oct  8 14:46:00 1986
Date-Received: Thu, 9-Oct-86 06:31:49 EDT
References: <762@oswego.UUCP>
Reply-To: occ4mgk@oac.ucla.edu, cc1@LOCUS.UCLA.EDU (Michael Gersten)
Distribution: net
Organization: Ucla Computer Club (disclaimer)
Lines: 28
Keywords: fork()

Neither fork() nor exec() can be written for the amiga. Why?
 
Fork(): What addresses are you going to fork? There is no way to find all
of your memory; the best you can get is program and stack. But, all those
non-relative addresses in your code will be wrong. All those pointers
on the stack will point to shared data.

Exec(): At some point, you have to unload yourself and load the next program.
If memory is a problem, you have to unload yourself first, and the loadseg()
might overwrite the exec() routine. If that isn't the problem, then
you can
forbid()
loadseg()
unloadseg()
?????
 
At this point, you Can Not just call the other routine, as permit() will never
be called. Start a new process? That has a few problems--you are no longer the
same process nor the same task (message port is different), but it solves the
killer permit problem. But it won't be identical to exec(), some of the
process data might not get copied over correctly (not sure just what AddProc()
does copy).
 
Exec() really should be an AmigaDos call. And yes, I did suggest this to
Amiga a while ago.
		Michael Gersten
      Views expressed here may not be those of the Computer Club, UCLA, or
  anyone in their left OR right mind.  And that's the name o' that tune.