[En-Nut-Discussion] arm port (RFC: Changing ARM mode)

[Alain M.]

Adam Dybkowski escreveu:
> Alain M. wrote:
> 
>> It will probably work with ARM7, but it looks more like a hack...
>> But it will not work anymore on Cortex...
> 
> Why? What is the clue difference between Cortex and ARM cores?

In ARM7, the priviledged mode is kind of not for protection... I don't 
know what good is a protection that can be turned off with one instruction.

In Cortex-M3, protectetion is real and to enforce that, SWI (was renamed 
to SVC) is the only way to switch out of user mode.

Of course, the address can be read from the stack and then jump back, 
but that is really ugly.

Alain