Locating pointer table to specific RAM address

rmaier — Tue, 20 Apr 2021 22:21:59 GMT

How does one go about specifying a specific address for a variable (in my case pointer table)?

I can get the pointer table to be placed at the specific RAM address, but it is not initialized with the correct data (or any data?).

I start by adding a section in MEMORY

MEMORY

{

FLASH_1 (RX) : ORIGIN = 0x00000000, LENGTH = 0x00000400

FLASH_CONFIG (RX) : ORIGIN = 0x00000400, LENGTH = 0x00000010

FLASH_2 (RX) : ORIGIN = 0x00000410, LENGTH = 0x0001BBF0

CAL_FLASH (RX) : ORIGIN = 0x0001C000, LENGTH = 0x00020000

PTR_TABLE (RW) : ORIGIN = 0x1FFFF000, LENGTH = 0x00000200

SRAM (RW) : ORIGIN = 0x1FFFF200, LENGTH = 0x00003E00

}

Then, I reserve the memory:

.ptrTable : AT(__DATA_ROM)

{

. = ALIGN(4);

_ptrTableSection = .; /* create a global symbol at PtrTable */

*(.ptrTable)

. = ALIGN(4);

} > PTR_TABLE

Finally, the romp:

.romp : AT(_romp_at)

{

__S_romp = _romp_at;

LONG(__DATA_ROM);

LONG(_ptrTableSection);

LONG(SIZEOF(.ptrTable));

LONG(__DATA_ROM + SIZEOF(.ptrTable));

LONG(_sdata);

LONG(___data_size);

LONG(0);

} > SRAM

For now, my work around is to define the pointer table as ROM data then copy this over at runtime manually to the RAM pointer table. There must be a better way of doing this. What am I doing wrong here?

Thanks,

Robert

Re: Locating pointer table to specific RAM address

jiri_kral — Wed, 21 Apr 2021 12:25:42 GMT

Hi,

I'm afraid that you will need some routine for copying data from Flash vector table into RAM. Technically it is the very same process as initialized variables.

The easiest way is left existing startup code and move your RAM vector table into your section:

Startup will copy data from Flash into RAM and setup VTOR register.

Jiri

Re: Locating pointer table to specific RAM address

rmaier — Wed, 21 Apr 2021 12:33:56 GMT

Thanks for your help Jiri. Much appreciated.

Robert

topic Re: Locating pointer table to specific RAM address in S32 Design Studio

Locating pointer table to specific RAM address

Re: Locating pointer table to specific RAM address

Re: Locating pointer table to specific RAM address