Memory protection on RTEMS?

[Sebastian Huber]

Hello Martin,

----- Martin Galvan <martin.galvan at tallertechnologies.com> schrieb:
> Hi there! We were looking at the RTEMS SMP support, and wondered what
> would it take for the system to support some form of memory protection
> (say, an MPU). Is it possible, and if so, how hard would it be?

the question is, what is "some form of memory protection" for you?

A process model for RTEMS makes no sense. For this you better use a micro kernel or Linux.

The ARMv7-A and some PowerPC BSPs have write protection for code and read-only data. On some BSPs, read/write to the NULL pointer leads to an exception.  This is quite handy during development, but offers no real benefit for a production system.

For one customer we implemented a stack protection, a thread can only access its own stack, but this is quite non-standard.

> 
> We also saw this:
> 
> https://devel.rtems.org/wiki/Projects/MMU_Support
> 
> What's the status of this project?

I don't know. MMU support tends to be highly architecture specific, so the development of a general purpose API is quite difficult.

> 
> On the other hand, we noticed that LEON3 IP Cores usually implement an
> MMU instead of just an MPU. Would it be feasible to support that?

The GR740 has an IOMMU (chapter 17).

http://microelectronics.esa.int/ngmp/GR740-UM-DS-v1.pdf

-- 
Sebastian Huber, embedded brains GmbH

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