TMS320F28377S: what is the requirement for stack assignment?

Part Number: TMS320F28377S

Hi,

A default cmd file in my project was assigning stack to RAMM1 with 0x400 of size. 

I tried to assign stack to RAMGS7. But the assignment lead to HW_init() failure.

Then the stack was assigned to RAMD1 with 0x800 of size. This assignement worked fine.

Is there specific rules for assigning stack? Why can't I assign stack to RAMGS?

Can I assign stack to both RAMM1 and RAMD1, using ".stack              : >> RAMM1 | RAMD1       PAGE = 1" ?

The datasheet is saying that  RAMD1 is secure memory. What is secure memory?

Kind regards

Orient