Memory protection in RTEMS

[Tomasz Gregorek]

2015-04-02 17:38 GMT+02:00 Gedare Bloom <gedare at rtems.org>:

> On Thu, Apr 2, 2015 at 11:19 AM, Tomasz Gregorek
> <tomasz.gregorek at gmail.com> wrote:
> > Hi Gedare
> >
> > Thank you for your comments, they answer my question.
> >
> > We will look at other RTOSes this time.
> >
> OK, I'd be happy to hear what you find or settle on. It's a topic that
> I have continued interest in working on for RTEMS.
>

I'll let you know.
So far I've seen some commercial RTOS with MPU. At the moment we consider
even Linux so you can say that the selection process is at early stage.

Tomasz


> Gedare
>
> > Thanks
> > Tomasz
> >
> > 2015-04-02 17:01 GMT+02:00 Gedare Bloom <gedare at rtems.org>:
> >>
> >> Hi Tomasz,
> >>
> >> It is possible to implement some memory protection between threads. As
> >> you noticed, RTEMS is a SASOS with "one process" when viewed from the
> >> POSIX interface. Generalizing memory protection in such a system is
> >> hard. The most common approach I know of is to provide separate
> >> protection domains for each thread stack. In theory, you could create
> >> a protection domain for the RTEMS "kernel", but I'm not aware of
> >> anyone that has tried hard to do that. You may also look for the "Zero
> >> Kernel" work some folks did as a research project at Univ of Idaho I
> >> think it was.
> >>
> >> If you want memory protection, you'd have to tailor it to your
> >> specific application requirements and set-up the MMU/MPU to do it.
> >> Final note: Since there is no notion of privilege in RTEMS, any thread
> >> can always disable or modify the protection domains since priviliged
> >> registers and instructions are available. Thus, while you may add
> >> memory protection, it would not be for a complete security solution.
> >>
> >> Gedare
> >>
> >> On Thu, Apr 2, 2015 at 10:04 AM, Tomasz Gregorek
> >> <tomasz.gregorek at gmail.com> wrote:
> >> > Hi
> >> >
> >> > We are investigating possible OSes for a new product where one of the
> >> > requirements is memory protection between processes.
> >> >
> >> > Does RTEMS supports memory protection? If not than is it planned to
> >> > implement memory protection?
> >> >
> >> > This is what I found so far:
> >> >
> >> > RTEMS is single process, multiple threads and as such have everything
> in
> >> > single memory space.
> >> > http://comments.gmane.org/gmane.os.rtems.user/19858
> >> >
> >> > Gedare's blog with his implementation of memory protection from
> >> > 2011/2012.
> >> >
> http://gedare-csphd.blogspot.be/2011/12/rtems-memory-protection-api.html
> >> > but it seems that this code didn't get to the main.
> >> >
> >> > Project "MMU Support" by Aanjhan Ranganathan from 6 years ago:
> >> > https://devel.rtems.org/wiki/Projects/MMU_Support
> >> >
> >> > Source code configures MMUs but it seems it do it to enable cache
> only,
> >> > not
> >> > the memory protection. Though I did only simple search through the
> code.
> >> > There are exception handlers for some architectures/CPUs but only for
> >> > few if
> >> > not for only one.
> >> >
> >> > Best regards
> >> > Tomasz Gregorek
> >> >
> >> > _______________________________________________
> >> > users mailing list
> >> > users at rtems.org
> >> > http://lists.rtems.org/mailman/listinfo/users
> >
> >
>
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