Re: LF: Supervisor Stack


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Re: LF: Supervisor Stack




> 
> On Thu, 5 Dec 1996, Shawn Walker wrote:
> 
> > 	The RAM.TXT file that comes with FARGO mentions a "Supervisor
> > Stack."  Upon browsing the 68k programmers guide, I could not determine
> > where, or what, the switch from the user's stack to the supervisor stack
> > takes place.  Could anyone shed some light on this for me.  Also, other
> > than exceptions and TRAP's, does the processor ever enter the supervisor
> > state.  How?  Other than the ability to execute privileged instructions,
> > and the setting of the supervisor flag in SR, does the change to
> > supervisor state change anything else.
> 
> The stacks are switched whenever the mode is switched, what's strange about 
> that? The SP-register (AKA A7) Holds the pointer of the current stack.
> 
> Exceptions, traps, interrupts - that's it. The state is meant for 
> operating system code, to protect it from usermode programs.
> 

Just thought I'd say.. Fargo programs are run in supervisor mode...

(I rember the good old days of teh ST, when every program switched to 
supervisor mode as pectically teh first thing they did!!)

Rob Taylor MAIL - mailto:rtaylor@ticalc.org 
           WEB  - http://www.u-net.com/~rtaylor/    


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