Default system heap listener

Question

How can a heap listener be used on the system heap? That is, the system heap that is used for k_malloc() and k_free(), with size set in kconfig as follows. The kconfig to enable the listener is also added 
 CONFIG_HEAP_MEM_POOL_SIZE=/* size in bytes */
CONFIG_SYS_HEAP_LISTENER=y 
 
 In particular, I'm trying to find out what _heap_id should be used with the macros 
 HEAP_LISTENER_ALLOC_DEFINE(name, _heap_id, _alloc_cb)
HEAP_LISTENER_FREE_DEFINE(name, _heap_id, _free_cb) 
 I tried using " HEAP_ID_LIBC " for the _heap_id in the above listener define macros. It builds, but no calls to the _alloc_cb or _free_cb functions occur, despite many uses of k_malloc() and k_free(). I would assume HEAP_ID_LIBC is for C library calls with malloc() and free(), and not the Zephyr memory pool heap functions k_malloc() and k_free(). 
 What should be used for the heap ID with the heap memory pool? Is there an example of using the heap listener API? 
 Thank you, 
 Walt

Jason · Accepted Answer

Hi, 
 wkpolara said: Regrettably, poor support is often a hallmark of open source software. 
 yes, but fortunately, in most cases, you may find out by reading the source code. 
 
 I have figured out how to get the default system heap. It is a global variable. 
 so you can call it simply as follow: 
 extern struct k_heap _system_heap; 
 void main_heap_listener_alloc_cbh ( uintptr_t heap_id , void * mem , size_t bytes ); 
 
 void main_heap_listener_free_cbh ( uintptr_t heap_id , void * mem , size_t bytes ); 
 
 HEAP_LISTENER_ALLOC_DEFINE (AllocListener, HEAP_ID_FROM_POINTER (&_system_heap.heap), main_heap_listener_alloc_cbh); 
 HEAP_LISTENER_FREE_DEFINE (FreeListener, HEAP_ID_FROM_POINTER (&_system_heap.heap), main_heap_listener_free_cbh);

Default system heap listener

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