STM32H743 cannot use all the available RAM about mbed-os HOT 8 OPEN

Hello,

sorry, but information in your main post are wrong.

MEMORY
{
FLASH (rx) : ORIGIN = MBED_APP_START, LENGTH = MBED_APP_SIZE
DTCMRAM (rwx) : ORIGIN = NVIC_RAM_VECTOR_ADDRESS + VECTORS_SIZE, LENGTH = 128K - VECTORS_SIZE
RAM (xrw) : ORIGIN = MBED_RAM_START, LENGTH = MBED_RAM_SIZE
RAM_D2 (xrw) : ORIGIN = 0x30000000, LENGTH = 288K
RAM_D3 (xrw) : ORIGIN = 0x38000000, LENGTH = 64K
ITCMRAM (xrw) : ORIGIN = 0x00000000, LENGTH = 64K
}

What version of Mbed-os are you using (tag or sha) ?

mbed-os-6.17.0

You wrote about wrong memory settings in MbedOS 6.17, but this memory setting is definitely not from Mbed OS 6.17.

• STM32H743xI.ld file
• msis_nvic.h

The memory settings from your post is from Mbed OS 6.15 or lower because it Mbed OS 6.15.1 was done a correction - #15130

BR, Jan

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Maybe @jeromecoutant know how to deals with it and use the other RAM sections ? :)

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cc @ARMmbed/team-st-mcd

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I remember NXP K64F has 2 RAM banks as well, RAM is split into two sections (if I am not wrong, you can't write through the boundaries).

See the linker script: https://github.com/ARMmbed/mbed-os/blob/master/targets/TARGET_Freescale/TARGET_MCUXpresso_MCUS/TARGET_MCU_K64F/device/TOOLCHAIN_GCC_ARM/MK64FN1M0xxx12.ld - you can review data and data 2 sections.
The first lower RAM is used for interrupts, heap and the second bank (larger) for user/app data.

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Thank you.

I managed to use the RAM_D2 by creating a section like that in the linker script :

SECTIONS
{
    ...
    .map_counters (NOLOAD):
    {
        KEEP(*(.map_counters))
    } >RAM_D2
}

Then, in my code i can instantiate vairables at this area like this:

static uint32_t map_counter[110][110] __attribute__((section(".map_counters")));

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Hello @JohnK1987

Indeed, to be exact we are using a custom target based on the STM32H753ZI. We are using Mbed OS 6.17.0 but the linker script of our custom targets comes from an older version of Mbed OS.

I didn't see that the linker script was updated, but the issue remains : it only use the 512k bank for user RAM.

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I'm not sure if there are any other solutions besides the one I detailed previously. So, unless you have another idea, we can close the issue :)

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I didn't see that the linker script was updated, but the issue remains : it only use the 512k bank for user RAM

Not fully true => Ethernet is using SRAM3:
https://github.com/ARMmbed/mbed-os/blob/master/connectivity/drivers/emac/TARGET_STM/stm32xx_emac.cpp#L113
https://github.com/ARMmbed/mbed-os/blob/master/targets/TARGET_STM/TARGET_STM32H7/TARGET_STM32H743xI/TOOLCHAIN_GCC_ARM/STM32H743xI.ld#L235

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