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

Harald Kipp harald.kipp at egnite.de
Sat Jan 17 10:50:39 CET 2009

Adam Dybkowski wrote:
> Harald Kipp wrote:
>> 5. As a first action we can change all ARM related crt routines to
>> properly set the user stack and enter NutInit in system mode. This is
>> easily done and shouldn't harm existing code.
> I think it will be useless because the system mode is almost the same as 
> supervisor, only working on other stack and registers. But it's 
> privileged as well. So why do this change?

That's right. Actually the change had been applied already, committed
late yesterday (CET). The main reason is, that applications (or upcoming
Nut/OS extensions) can make use of SWI. Another reason is, that it would
confuse too many people having Nut/OS applications running on supervisor
registers, while the rest of the world uses user mode registers. It even
confused me while trying to implement Duane's stack backtrace.


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