Puzzle about SYSBIOS's Dynamic memory alloc

Hi all:

      In DSP/BIOS,I can alloc memory in desired address like this :

1: I create a memory by dspbios

2 write code:(float*) pInt=(float *)MEM_calloc(IRAM_HEAP, 1024*sizeof(float), 8);

Then I konw that i create a bufer which address is between 0x10002400 and (0x10002400+0x0003dc00) and bufsize is 1024*sizeof(float)

So I can alloc buf to ethier RAM or DDR.

But by SYSBIOS all I konw to create buf dynamically like this:

new a heapbuf

the IRAM_heap will be created in DDR because my Data Memory is DDR like bellow

if I  change the data memory to IRAM ,the IRAM_heap wii be created  in IRAM.

The problam is that it is impossible to set IRAM which is very small as Data Memory.I wana alloc a little data frequently used to IRAM whose speed is fast,the other datas are alloced in DDR,The DDR is setted as Data Memory,but how can I alloc heap in IRAM in this situation.

Thanks for your reply