AM2612-Q1: AM261 OCSRAM questions

Kita Li said:

Now customer found that their SBL and APP occupy the same portion of OCSRAM.Address 0x70040000-0x70071FFF overlaps for SBL and APP. Customer wants to know if it has risk when SBL and APP occupy same RAM address.

Hi Kita,

No, this is safe and expected behavior. The application is put to RAM from flash only after loading the HSMRT. By "Loading HSMRT", it means to put the HSMRT firmware from OCRAM to HSM_RAM. So overwriting this shouldn't be a problem.

If customer wants to store a variable at a specific address in flash memory, follow these steps:

In linker command file (.cmd), define a new memory region with your desired flash address:

MEMORY
{
/* Standard memory regions */
OCSRAM : origin = 0x70000000, length = 0x80000
FLASH : origin = 0x60100000, length = 0x800000

/* Custom flash region at specific address */
FLASH_FIXED_VARIABLE : origin = 0x6010xxxx, length = 0x1000 /* Replace xxxx with your offset */
}

In the SECTIONS part of your linker file:

SECTIONS
{
/* Standard sections */
.text : {} > OCSRAM
.data : {} > OCSRAM
.bss : {} > OCSRAM

/* Custom section mapped to specific flash address */
.flash_code : {} > FLASH_FIXED_VARIABLE
}

In your C source code, use the section attribute to place variables/functions in the custom flash section:

__attribute__((section(".flash_code")))
const uint32_t myFixedVariable = 0x12345678;

Best Regards,

Mayank Shadwani