[En-Nut-Discussion] arm port (RFC: Changing ARM mode)
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.
More information about the En-Nut-Discussion