Move RAM partition with ARM compiler

[VVESTM]

Description

I would like to move the RAM partition on NUCLEO_H743ZI board. For now, I am able to do it with IAR and GCC_ARM toolchains but not with ARM one.

After my developments for ethernet on STM32H7 (see here PR #11274), I faced some issue with those tests :

tests-mbed_platform-crash_reporting
tests-mbedmicro-rtos-mbed-heap_and_stack

For those tests, it seems I need to keep the vector table and crash report ram to 0x20000000.
Regarding that, I decided to move only the RAM from 0x20000000 to 0x24000000.

I can do it for IAR and GCC_ARM, this is temporary available in my GitHub account : branch and commit.

For ARM, I cannot succeed to perform the same modification. I have tried this in stm32h743xI.sct :

#define MBED_RAM_START 0x24000000
#define MBED_RAM_SIZE 0x80000
#define MBED_VECTTABLE_RAM_START 0x20000000
#define MBED_VECTTABLE_RAM_SIZE 0x298
#define MBED_CRASH_REPORT_RAM_START (MBED_VECTTABLE_RAM_START + MBED_VECTTABLE_RAM_SIZE)
#define MBED_CRASH_REPORT_RAM_SIZE 0x100
#define MBED_RAM0_START (MBED_RAM_START)
#define MBED_RAM0_SIZE (MBED_RAM_SIZE)

But it seems there is no effect and the MSP stay in 0x20000000 area... (tests-mbedmicro-rtos-mbed-heap_and_stack test failed because msp is 0x2001ff70) :
mbed test -t GCC_ARM -m NUCLEO_H743ZI -v -n tests-mbedmicro-rtos-mbed-heap_and_stack

Do you know if there is an other place to modify in order to move RAM with ARM toolchain ?
Is there some hardcoded values that forbid user to move RAM ?

For information, I also tried to exchange IRAM1 and IRAM2 sections in https://github.com/ARMmbed/mbed-os/blob/master/tools/arm_pack_manager/index.json file with no success.

Issue request type

[X] Question
[ ] Enhancement
[ ] Bug

[jeromecoutant]

@kjbracey-arm

[kjbracey]

Initial stack pointer is specified here - doesn't come from the linker map:

mbed-os/targets/TARGET_STM/TARGET_STM32H7/TARGET_STM32H743xI/device/TOOLCHAIN_ARM_STD/startup_stm32h743xx.S

Line 27 in a1540c5

__initial_sp EQU 0x20020000 ; Top of RAM

[VVESTM]

Thanks @kjbracey-arm. Seems to be better if I set __initial_sp to 0x24080000.
No way to calculate this value from .sct file ?

I will perform a full test campaign to be sure nothing else is broken. I will then update this ticket.

[kjbracey]

Sure, I believe

              IMPORT |Image$$ARM_LIB_STACK$$ZI$$Limit|

__Vectors     DCD    |Image$$ARM_LIB_STACK$$ZI$$Limit|                ; Top of Stack

should do it.

(Corrected - original EQU version was wrong)

[VVESTM]

Thanks @kjbracey-arm. As discussed with you, the exact solution to add in .S file is :
IMPORT |Image$$ARM_LIB_STACK$$ZI$$Limit|
__Vectors DCD |Image$$ARM_LIB_STACK$$ZI$$Limit| ; Top of Stack

I have still some issue with IAR toolchain now. I will push a new PR as soon as I have the 3 toolchains working (ARM, GCC_ARM and IAR)