Re: LF: Supervisor Stack

Re: LF: Supervisor Stack

• To: list-fargo@lists.ticalc.org
• Subject: Re: LF: Supervisor Stack
• From: Jonas Minnberg <md94-jmi@nada.kth.se>
• Date: Thu, 5 Dec 1996 21:20:05 +0100 (MET)
• In-Reply-To: <Pine.SOL.3.93.961205144452.1513A-100000@joe.math.uga.edu>
• Reply-To: list-fargo@lists.ticalc.org

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.

//Sasq (Jonas Minnberg)

• LF: Supervisor Stack
• From: Shawn Walker <swalker@joe.math.uga.edu>

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