Dynamic Memory Allocation in OnChip-Ram

[Altera_Forum]

Hello, 

I am looking for a possibility to dynamically allocate memory in OnChip-RAM, while heap is in external RAM.  Has anyone experiences regarding this topic?

[Altera_Forum]

Basically no, if You're talking about malloc(). Why not to use direct addressing?

[Altera_Forum]

Yes Socrates, I'm talking about malloc(). 

 The thing is, that I want to improve the LwIp-Stack and there some structures (e.g. ethernetif, pbuf) allocated dynamically.  As a workaround I did allocate the memory statically, but I think for a better structural design it would be nicer to allocate those structures dynamically at internal RAM.  Maybe a solution could be to reassign the heap to internal RAM, then malloc(), and then put the Heap back to external RAM. But the LwIp malloc-function saves and uses the lowest free block for allocation, which is always in external Ram.  Sure, I know that I could write my own malloc(), but I wanted to know if someone knows an easier or more common way.

[Altera_Forum]

For embedded use it is actually better to avoid malloc() - except maybe at startup. That way you don't suddenly run out of memory in some important code path.

[Altera_Forum]

Or suffer from memory fragmentation. In my experience you have to be VERY careful with dynamic memory allocation in embedded applications.