Re: [Xenomai-help] RT Heap in Userspace

[Jan Kiszka <jan.kiszka@domain.hid>]

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Stephan Zimmermann wrote:
> Hello again,
> based on your information about memory allocation, I tried out the following:
> 
> in main:
> // creating the Heap
> ret = rt_heap_create(&rt_heap,"Main-RT-Heap",rt_heapsize,H_FIFO);
> 
> global:
> // overloaded operator new 
> void* operator new(size_t size){
> 	void* newmem = NULL;
> 	int ret = rt_heap_alloc(&rt_heap,size,TM_INFINITE,&newmem);
> 	printf("new memory allocated: %i bytes, return %i\n",size,ret); fflush(NULL);
> 	return newmem;
> }
> 
> This works fine, as long as I use a standard 'malloc' in my operator new. When 
> executing the rt_... code, creating the heap returns 0 as expected. But 
> trying to allocate some Memory insode of it using operator new fails with 
> -EEINVAL.
> 
> Reading the API-Doc more thoroughly, I saw a statement that H_SHARED is 
> implicitly set, when a heap is created from Userspace (where my program 
> executes).
> So, is ist possible to do what I try, or will I need to run in kernelspace for 
> it? Maybe there is some 'trick' to do it?
> 

If you do not depend on sharing the allocated memory between multiple
processes or kernel and user space, you may want to take a look at this
deterministic allocator library:

http://rtportal.upv.es/rtmalloc/allocators/tlsf/index.shtml

Should be straightforward to use it (at least it was with a previous
version I once tried).

Jan


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