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

[Thiago A. Corrêa]

On Wed, Jan 14, 2009 at 7:54 PM, Adam Dybkowski <adybkows at wp.pl> wrote:
>
> Running user applications in user mode will improve security but also

Well, that is true for a real operating system, but Nut/OS is actually
just a library.
If something goes wrong, there is no "killing the offending application".
It might solve some other problem though, not sure.

> slow down system calls and overall performance. I think this should be a
> configurable option in the future (if unselected, falling back to
> current all-code-in-supervisor-mode), not the only choice.
>

That's true, and will make your code a little bit bigger as well. So,
if this could be avoided, it would probably be best. It doesn't have
to be supervisor mode, perhaps run all code in some intermediary mode
if one exists :P
I don't know ARM, so I can't say much, but from what I understud from
the thread, the architecture doesn't give us much choice in the matter
:(

I'm looking in detail over the AVR32 archtecture.... but I haven't yet
found such a restriction there in the documents I'm looking over
(Technical Reference Manual, Architecture Manual, Datasheet and
Errata). But I guess that's for some other thread to discuss :D

Regards,
    Thiago A. Correa