Allocate memory within an application and modify its access permissions

[Sebastian Huber]

On 2013-08-28 02:00, Hesham Moustafa wrote:
> Hey all,
>
> I want to allocate memory within an application code, set
> memory access attributes on it, and check whether these
> permissions are set correctly or not.
>
> I tried to use _Workspace_Allocate(), malloc(), and partition and region
> managers to allocate a region of memory, but just after I set the
> allocated region to READ_ONLY attribute, an exception occurs. There is
> no problem when I set WRITE attribute. Also when I use hard-coded
> addresses ( that do not belong to any used section by RTEMS), I get it
> working correctly.

Why do you get an exception?  The heap manager places some administration data 
right at the begin and end of an allocated block.  See also

http://www.rtems.org/onlinedocs/doxygen/cpukit/html/group__RBHeap.html

>
> Is there a way to allocate memory without hard-coded addresses
> (target-independent), or the previous "exception-after-set" problem ?
>
> Regards,
> Hesham
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>


-- 
Sebastian Huber, embedded brains GmbH

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