Dynamic memory allocation in PSRAM

[SSG]

Hi,

Currently I am using STM32L4R9 discovery board, which has 16-Mbit (2MB) PSRAM. I have been able to allocate static memory inside PSRAM by using following code and also by changing linker script file (.ld). I have attached my edited linker script with this post.

int __attribute__((section (".psram_data"))) psram_buffer[50000];

for(int i=0; i<50000; i++)
{
psram_memory[i] = i;
}

But, how can I dynamically allocate memory by using malloc() / calloc() inside PSRAM. If possible, please share some example code with me.

Thank you.

[Nikita91]

Reserve a block of memory in PSRAM, then allocate subblocks.

You can take inspiration from one of the allocators present in FreeRTOS for example.

[FBL]

Hello @SSG 

You can define a custom memory region in PSRAM as the heap using the linker script. Here is an example project to do this. 

[SofLit · Accepted solution]

Hello,

In your linker file try the following:

MEMORY
{
....

....
PSRAM_HEAP (xrw) : ORIGIN = <put the PSRAM start address>, LENGTH = <put the heap region size>
}

..

..

._user_heap :
{
. = ALIGN(8);
PROVIDE ( s_heap = . );
. = . + Heap_Size;
. = ALIGN(8);
PROVIDE ( e_heap = . );
} >PSRAM_HEAP

B.R.

[Tesla DeLorean]

That might work if not for the horrific _sbrk implementation you have..

[SSG]

Thanks. I will try this.

[SSG]

Okay. I will have a look on that. Thanks