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STM32H723 RAM configuration

PUrsu.1
Associate II

Hey there,

I am trying to replace an STM32F767 with an H723ZGT Nucleo Board. The projects uses a lot of heap - in the predefined memory configuration there is not enough place in the RAM_D1 sector. What do I need to do for changing the available RAM size for the heap?

This is the default configuration:

/*
******************************************************************************
**
**  File        : LinkerScript.ld
**
**  Author      : STM32CubeIDE
**
**  Abstract    : Linker script for STM32H7 series
**                1024Kbytes FLASH and 560Kbytes RAM
**
**                Set heap size, stack size and stack location according
**                to application requirements.
**
**                Set memory bank area and size if external memory is used.
**
**  Target      : STMicroelectronics STM32
**
**  Distribution: The file is distributed as is, without any warranty
**                of any kind.
**
*****************************************************************************
** @attention
**
** Copyright (c) 2022 STMicroelectronics.
** All rights reserved.
**
** This software is licensed under terms that can be found in the LICENSE file
** in the root directory of this software component.
** If no LICENSE file comes with this software, it is provided AS-IS.
**
****************************************************************************
*/
 
/* Entry Point */
ENTRY(Reset_Handler)
 
/* Highest address of the user mode stack */
_estack = ORIGIN(RAM_D1) + LENGTH(RAM_D1);    /* end of RAM */
/* Generate a link error if heap and stack don't fit into RAM */
_Min_Heap_Size = 0x200 ;      /* required amount of heap  */
_Min_Stack_Size = 0x400 ; /* required amount of stack */
 
/* Specify the memory areas */
MEMORY
{
  ITCMRAM (xrw)    : ORIGIN = 0x00000000,   LENGTH = 64K
  DTCMRAM (xrw)    : ORIGIN = 0x20000000,   LENGTH = 128K
  FLASH    (rx)    : ORIGIN = 0x08000000,   LENGTH = 1024K
  RAM_D1  (xrw)    : ORIGIN = 0x24000000,   LENGTH = 320K
  RAM_D2  (xrw)    : ORIGIN = 0x30000000,   LENGTH = 32K
  RAM_D3  (xrw)    : ORIGIN = 0x38000000,   LENGTH = 16K
}
 
/* Define output sections */
SECTIONS
{
  /* The startup code goes first into FLASH */
  .isr_vector :
  {
    . = ALIGN(4);
    KEEP(*(.isr_vector)) /* Startup code */
    . = ALIGN(4);
  } >FLASH
 
  /* The program code and other data goes into FLASH */
  .text :
  {
    . = ALIGN(4);
    *(.text)           /* .text sections (code) */
    *(.text*)          /* .text* sections (code) */
    *(.glue_7)         /* glue arm to thumb code */
    *(.glue_7t)        /* glue thumb to arm code */
    *(.eh_frame)
 
    KEEP (*(.init))
    KEEP (*(.fini))
 
    . = ALIGN(4);
    _etext = .;        /* define a global symbols at end of code */
  } >FLASH
 
  /* Constant data goes into FLASH */
  .rodata :
  {
    . = ALIGN(4);
    *(.rodata)         /* .rodata sections (constants, strings, etc.) */
    *(.rodata*)        /* .rodata* sections (constants, strings, etc.) */
    . = ALIGN(4);
  } >FLASH
 
  .ARM.extab   : { *(.ARM.extab* .gnu.linkonce.armextab.*) } >FLASH
  .ARM : {
    __exidx_start = .;
    *(.ARM.exidx*)
    __exidx_end = .;
  } >FLASH
 
  .preinit_array     :
  {
    PROVIDE_HIDDEN (__preinit_array_start = .);
    KEEP (*(.preinit_array*))
    PROVIDE_HIDDEN (__preinit_array_end = .);
  } >FLASH
 
  .init_array :
  {
    PROVIDE_HIDDEN (__init_array_start = .);
    KEEP (*(SORT(.init_array.*)))
    KEEP (*(.init_array*))
    PROVIDE_HIDDEN (__init_array_end = .);
  } >FLASH
 
  .fini_array :
  {
    PROVIDE_HIDDEN (__fini_array_start = .);
    KEEP (*(SORT(.fini_array.*)))
    KEEP (*(.fini_array*))
    PROVIDE_HIDDEN (__fini_array_end = .);
  } >FLASH
 
  /* used by the startup to initialize data */
  _sidata = LOADADDR(.data);
 
  /* Initialized data sections goes into RAM, load LMA copy after code */
  .data :
  {
    . = ALIGN(4);
    _sdata = .;        /* create a global symbol at data start */
    *(.data)           /* .data sections */
    *(.data*)          /* .data* sections */
    *(.RamFunc)        /* .RamFunc sections */
    *(.RamFunc*)       /* .RamFunc* sections */
 
    . = ALIGN(4);
    _edata = .;        /* define a global symbol at data end */
  } >RAM_D1 AT> FLASH
 
  /* Uninitialized data section */
  . = ALIGN(4);
  .bss :
  {
    /* This is used by the startup in order to initialize the .bss section */
    _sbss = .;         /* define a global symbol at bss start */
    __bss_start__ = _sbss;
    *(.bss)
    *(.bss*)
    *(COMMON)
 
    . = ALIGN(4);
    _ebss = .;         /* define a global symbol at bss end */
    __bss_end__ = _ebss;
  } >RAM_D1
 
  /* User_heap_stack section, used to check that there is enough RAM left */
  ._user_heap_stack :
  {
    . = ALIGN(8);
    PROVIDE ( end = . );
    PROVIDE ( _end = . );
    . = . + _Min_Heap_Size;
    . = . + _Min_Stack_Size;
    . = ALIGN(8);
  } >RAM_D1
 
  /* Remove information from the standard libraries */
  /DISCARD/ :
  {
    libc.a ( * )
    libm.a ( * )
    libgcc.a ( * )
  }
 
  .ARM.attributes 0 : { *(.ARM.attributes) }
}

Thank you all in advance for trying to help me - now I just need a solution but in the near future I need to work on my knowledge regarding memory management.

4 REPLIES 4

>>The projects uses a lot of heap - in the predefined memory configuration there is not enough place in the RAM_D1 sector.

How much, and where's it going to come from? The NUCLEO doesn't have SDRAM

The ST GNU/GCC implementation doesn't really allow for pools in different/multiple regions.

Check the _sbrk() implementation, usually in syscalls or newlib

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I already thought that pools over multiple regions are not that easy. In general I need to store various data structs and FreeRTOS has a TOTAL_HEAPSIZE of 250.000.

The largest contiguous block of RAM is 320KB

What you might want to do is direct other usages over into the 64KB (ITCM), 128KB (DTCM), 32KB (SRAM1+SRAM2) or 16KB (SRAM4) sections

Use the __attribute__ directive.

You'll have to probably rework the startup.s code to initialize things.

You might be able to simplify this by having just the HEAP/STACK in the 320KB region, and having everything else in the DTCMRAM 128KB

Keil manages the initialization better via tables, as does ARDUINO/GCC, and Keil I can push memory regions into the heap's block list.

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/*
******************************************************************************
**
**  File        : LinkerScript.ld
**
**  Author      : STM32CubeIDE
**
**  Abstract    : Linker script for STM32H7 series
**                1024Kbytes FLASH and 560Kbytes RAM
**
**                Set heap size, stack size and stack location according
**                to application requirements.
**
**                Set memory bank area and size if external memory is used.
**
**  Target      : STMicroelectronics STM32
**
**  Distribution: The file is distributed as is, without any warranty
**                of any kind.
**
*****************************************************************************
** @attention
**
** Copyright (c) 2022 STMicroelectronics.
** All rights reserved.
**
** This software is licensed under terms that can be found in the LICENSE file
** in the root directory of this software component.
** If no LICENSE file comes with this software, it is provided AS-IS.
**
****************************************************************************
*/
 
/* Entry Point */
ENTRY(Reset_Handler)
 
/* Highest address of the user mode stack */
_estack = ORIGIN(RAM_D1) + LENGTH(RAM_D1);    /* end of RAM */
/* Generate a link error if heap and stack don't fit into RAM */
_Min_Heap_Size = 0x200 ;      /* required amount of heap  */
_Min_Stack_Size = 0x400 ; /* required amount of stack */
 
/* Specify the memory areas */
MEMORY
{
  ITCMRAM (xrw)    : ORIGIN = 0x00000000,   LENGTH = 64K
  DTCMRAM (xrw)    : ORIGIN = 0x20000000,   LENGTH = 128K
  FLASH    (rx)    : ORIGIN = 0x08000000,   LENGTH = 1024K
  RAM_D1  (xrw)    : ORIGIN = 0x24000000,   LENGTH = 320K
  RAM_D2  (xrw)    : ORIGIN = 0x30000000,   LENGTH = 32K
  RAM_D3  (xrw)    : ORIGIN = 0x38000000,   LENGTH = 16K
}
 
/* Define output sections */
SECTIONS
{
  /* The startup code goes first into FLASH */
  .isr_vector :
  {
    . = ALIGN(4);
    KEEP(*(.isr_vector)) /* Startup code */
    . = ALIGN(4);
  } >FLASH
 
  /* The program code and other data goes into FLASH */
  .text :
  {
    . = ALIGN(4);
    *(.text)           /* .text sections (code) */
    *(.text*)          /* .text* sections (code) */
    *(.glue_7)         /* glue arm to thumb code */
    *(.glue_7t)        /* glue thumb to arm code */
    *(.eh_frame)
 
    KEEP (*(.init))
    KEEP (*(.fini))
 
    . = ALIGN(4);
    _etext = .;        /* define a global symbols at end of code */
  } >FLASH
 
  /* Constant data goes into FLASH */
  .rodata :
  {
    . = ALIGN(4);
    *(.rodata)         /* .rodata sections (constants, strings, etc.) */
    *(.rodata*)        /* .rodata* sections (constants, strings, etc.) */
    . = ALIGN(4);
  } >FLASH
 
  .ARM.extab   : { *(.ARM.extab* .gnu.linkonce.armextab.*) } >FLASH
  .ARM : {
    __exidx_start = .;
    *(.ARM.exidx*)
    __exidx_end = .;
  } >FLASH
 
  .preinit_array     :
  {
    PROVIDE_HIDDEN (__preinit_array_start = .);
    KEEP (*(.preinit_array*))
    PROVIDE_HIDDEN (__preinit_array_end = .);
  } >FLASH
 
  .init_array :
  {
    PROVIDE_HIDDEN (__init_array_start = .);
    KEEP (*(SORT(.init_array.*)))
    KEEP (*(.init_array*))
    PROVIDE_HIDDEN (__init_array_end = .);
  } >FLASH
 
  .fini_array :
  {
    PROVIDE_HIDDEN (__fini_array_start = .);
    KEEP (*(SORT(.fini_array.*)))
    KEEP (*(.fini_array*))
    PROVIDE_HIDDEN (__fini_array_end = .);
  } >FLASH
 
  /* used by the startup to initialize data */
  _sidata = LOADADDR(.data);
 
  /* Initialized data sections goes into RAM, load LMA copy after code */
  .data :
  {
    . = ALIGN(4);
    _sdata = .;        /* create a global symbol at data start */
    *(.data)           /* .data sections */
    *(.data*)          /* .data* sections */
    *(.RamFunc)        /* .RamFunc sections */
    *(.RamFunc*)       /* .RamFunc* sections */
 
    . = ALIGN(4);
    _edata = .;        /* define a global symbol at data end */
  } >DTCMRAM AT> FLASH
 
  /* Uninitialized data section DTCMRAM*/
  . = ALIGN(4);
  .bss :
  {
    /* This is used by the startup in order to initialize the .bss section */
    _sbss = .;         /* define a global symbol at bss start */
    __bss_start__ = _sbss;
    *(.bss)
    *(.bss*)
    *(COMMON)
 
    . = ALIGN(4);
    _ebss = .;         /* define a global symbol at bss end */
    __bss_end__ = _ebss;
  } >DTCMRAM
 
  /* Uninitialized data section SRAM1+SRAM2 RAM_D2 32KB */
  . = ALIGN(4);
  .bss_d2 :
  {
    /* This is used by the startup in order to initialize the .bss_d2 section */
    _sbss_d2 = .;         /* define a global symbol at bss_d2 start */
    __bss_d2_start__ = _sbss_d2;
    *(.bss_d2)
    *(.bss_d2*)
    *(COMMON)
 
    . = ALIGN(4);
    _ebss_d2 = .;         /* define a global symbol at bss_d2 end */
    __bss_d2_end__ = _ebss_d2;
  } >RAM_D2
 
  /* Uninitialized data section SRAM4 RAM_D3 16KB */
  . = ALIGN(4);
  .bss_d3 :
  {
    /* This is used by the startup in order to initialize the .bss_d3 section */
    _sbss_d3 = .;         /* define a global symbol at bss_d3 start */
    __bss_d3_start__ = _sbss_d3;
    *(.bss_d3)
    *(.bss_d3*)
    *(COMMON)
 
    . = ALIGN(4);
    _ebss_d3 = .;         /* define a global symbol at bss_d3 end */
    __bss_d3_end__ = _ebss_d3;
  } >RAM_D3
 
  /* User_heap_stack section, used to check that there is enough RAM left */
  ._user_heap_stack :
  {
    . = ALIGN(8);
    PROVIDE ( end = . );
    PROVIDE ( _end = . );
    . = . + _Min_Heap_Size;
    . = . + _Min_Stack_Size;
    . = ALIGN(8);
  } >RAM_D1
 
  /* Remove information from the standard libraries */
  /DISCARD/ :
  {
    libc.a ( * )
    libm.a ( * )
    libgcc.a ( * )
  }
 
  .ARM.attributes 0 : { *(.ARM.attributes) }
}

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