Azure RTOS byte pool problem

Question

Hi,

I am having issues with threadX tx_byte_allocate throwing a hard fault exception. 

This only happens after some time of byte allocate and release. There are still plenty of available bytes according to the pool. But somehow in _tx_byte_pool_search it encounters some problem. 

I am not posting the entire source code here as that will be huge.

For reference only, I am using STM32H753. I created a byte pool using DTCRAM (128K).

Linker snippet:

RAM (xrw) : ORIGIN = 0x20000000, LENGTH = 128K

.ram_dtcmram :

{

*(.ram_dtcmram)

} >RAM

 

 

 

Code Snippet

#define RAM_DTCMRAM \

attribute((section(".ram_dtcmram")))

#define GENERIC_MEM_ALLOCATION (0x20000-0x1000)

 

static u8 m_genericMemBytePoolBuffer[GENERIC_MEM_ALLOCATION] RAM_DTCMRAM;

static TX_BYTE_POOL m_genericMemBytePool RAM_D3;

 

bool Hal_MemPool_Init(void)

{

if (tx_byte_pool_create(&m_genericMemBytePool, "Generic memory pool", m_genericMemBytePoolBuffer , GENERIC_MEM_ALLOCATION) != TX_SUCCESS){

return FALSE;

}

return TRUE;

}

 

This  is the screenshot of the pool when the hard fault happens. byte pool available is still more than 50k

Below are the local variables during the fault. As you can see current pointer goes to 0x2492bc7e. That memory is not available for H753 and obviously will throw a hard fault error trying to access this memory.

Specifically on line below inside the do while(examine_blocks != ((UINT) 0)) loop

work_ptr = TX_UCHAR_POINTER_ADD(current_ptr, (sizeof(UCHAR *)));

free_ptr = TX_UCHAR_TO_ALIGN_TYPE_POINTER_CONVERT(work_ptr);

if ((*free_ptr) == TX_BYTE_BLOCK_FREE) //<-----------HARD FAULT

Now my question is why? Clearly, I have enough available bytes in the pool. You can also see below that the memory required is only 256 bytes. Even if the memory gets fragmented, I am pretty confident there is a block with 256 bytes free on it. Besides, ThreadX is supposed to merge those splits or fragments. Which is also stated in the pool above (tx_byte_pool_performance_merge_count)

Version of ThreadX is 

Not that it matters I think, I made the pool  m_genericMemBytePool the same RAM as the m_genericMemBytePoolBuffer to dtcmram. Same outcome.

 

Thanks,

Carlo

Answer 1

Hi @flaming_vines Greetings! Welcome to Microsoft Q&A forum. Thank you for posting this question here.

Thank you for reporting this issue here and providing the details of your investigation and findings. You may have identified a bug in the RTOS ThreadX version 6.2.0. I request you to report the issue on Github repository link - Azure RTOS ThreadX issues

The product team actively maintains the repository code and you would get direct assistance from the team on the repository. Kindly share the link of the GitHub issue once you get to open it so that other community members running into this issue can monitor it.

Hope this helps.

Bug Tracking

https://github.com/azure-rtos/threadx/issues/309