Memory protection in RTEMS

[Tomasz Gregorek]

Hi Gedare

Thank you for your comments, they answer my question.

We will look at other RTOSes this time.

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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