Setup a fixed address for global variable

[Ecohe]

I am need to set a fixed address for global variable

1. For several variables.

2. For several const variable.

I have tried to search information and examples on this matter, but was unsatisfied.

I am using STM32F413VGTX, STM32CubeIDE

There is two ID files.

1. STM32F413VGTX_FLASH.id

2. STM32F413VGTX_RAM.id

On the linker setting(-T) it point to 'STM32F413VGTX_FLASH.id'

This is example i has tried to, but wont work(dosnt pointed to the right address):

In main.c:

__attribute__((section(".ARM.__at_0x20000420")))

char g_test1[100] = {0};

In ID fille:

.ARM.__at_0x20000400 0x20000400 :{KEEP(*(.ARM.__at_0x20000400))}>.data

when i edit 'STM32F413VGTX_RAM.id' it not set the right address(does not do nothing).

The generated 'xxxxx.list' file shows:

......

 8 .data     00005d84 20000000 080f16a8 00110000 2**3

         CONTENTS, ALLOC, LOAD, DATA

 9 .ARM.__at_0x20000420 00000064 20005d84 080f742c 00115d84 2**2

.....

When i edit STM32F413VGTX_FLASH.id

i have error: section .ARM.__at_0x20000400 VMA [0000000020000400,000000002000040f] overlaps section .data VMA [0000000020000000,0000000020005d83]

any suggestion how to solve it?

STM32F413VGTX_FLASH.id:

/*

******************************************************************************

**

** @file    : LinkerScript.ld

**

** @author   : Auto-generated by STM32CubeIDE

**

** @brief    : Linker script for STM32F413VGTx Device from STM32F4 series

**           1024Kbytes FLASH

**           320Kbytes 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

**

** <h2><center>&copy; Copyright (c) 2021 STMicroelectronics.

** All rights reserved.</center></h2>

**

** This software component is licensed by ST under BSD 3-Clause license,

** the "License"; You may not use this file except in compliance with the

** License. You may obtain a copy of the License at:

**            opensource.org/licenses/BSD-3-Clause

**

******************************************************************************

*/

/* Entry Point */

ENTRY(Reset_Handler)

/* Highest address of the user mode stack */

_estack = ORIGIN(RAM) + LENGTH(RAM); /* end of "RAM" Ram type memory */

_Min_Heap_Size = 0x60; /* required amount of heap */

_Min_Stack_Size = 0x800; /* required amount of stack */

/* Memories definition */

MEMORY

{

 RAM  (xrw)  : ORIGIN = 0x20000000,  LENGTH = 320K

 FLASH  (rx)  : ORIGIN = 0x8000000,  LENGTH = 1024K

}

/* Sections */

SECTIONS

{

 /* The startup code into "FLASH" Rom type memory */

 .isr_vector :

 {

  . = ALIGN(4);

  KEEP(*(.isr_vector)) /* Startup code */

  . = ALIGN(4);

 } >FLASH

 /* The program code and other data into "FLASH" Rom type memory */

 .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 into "FLASH" Rom type memory */

 .rodata :

 {

  . = ALIGN(4);

  *(.rodata)     /* .rodata sections (constants, strings, etc.) */

  *(.rodata*)    /* .rodata* sections (constants, strings, etc.) */

  . = ALIGN(4);

 } >FLASH

 .ARM.extab  : {

  . = ALIGN(4);

  *(.ARM.extab* .gnu.linkonce.armextab.*)

  . = ALIGN(4);

 } >FLASH

 .ARM : {

  . = ALIGN(4);

  __exidx_start = .;

  *(.ARM.exidx*)

  __exidx_end = .;

  . = ALIGN(4);

 } >FLASH

 .preinit_array   :

 {

  . = ALIGN(4);

  PROVIDE_HIDDEN (__preinit_array_start = .);

  KEEP (*(.preinit_array*))

  PROVIDE_HIDDEN (__preinit_array_end = .);

  . = ALIGN(4);

 } >FLASH

 .init_array :

 {

  . = ALIGN(4);

  PROVIDE_HIDDEN (__init_array_start = .);

  KEEP (*(SORT(.init_array.*)))

  KEEP (*(.init_array*))

  PROVIDE_HIDDEN (__init_array_end = .);

  . = ALIGN(4);

 } >FLASH

 .fini_array :

 {

  . = ALIGN(4);

  PROVIDE_HIDDEN (__fini_array_start = .);

  KEEP (*(SORT(.fini_array.*)))

  KEEP (*(.fini_array*))

  PROVIDE_HIDDEN (__fini_array_end = .);

  . = ALIGN(4);

 } >FLASH

 /* Used by the startup to initialize data */

 _sidata = LOADADDR(.data);

 /* Initialized data sections into "RAM" Ram type memory */

 .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 AT> FLASH

 /* Uninitialized data section into "RAM" Ram type memory */

 . = 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

 /* User_heap_stack section, used to check that there is enough "RAM" Ram type memory left */

 ._user_heap_stack :

 {

  . = ALIGN(8);

  PROVIDE ( end = . );

  PROVIDE ( _end = . );

  . = . + _Min_Heap_Size;

  . = . + _Min_Stack_Size;

  . = ALIGN(8);

 } >RAM

 /* Remove information from the compiler libraries */

 /DISCARD/ :

 {

  libc.a ( * )

  libm.a ( * )

  libgcc.a ( * )

 }

 .ARM.attributes 0 : { *(.ARM.attributes) }

}

[MM..1]

LD files is for linking code run from flash or ram. Normal situation is used only one flash. And for place any data to direct area you need split RAM as first for example

MEMORY
{
 RAM  (xrw)  : ORIGIN = 0x20000000,  LENGTH = 320K
 FLASH  (rx)  : ORIGIN = 0x8000000,  LENGTH = 1024K
}
 
change to
 
MEMORY
{
 RAM0  (xrw)  : ORIGIN = 0x20000000,  LENGTH = 1K
 RAM  (xrw)  : ORIGIN = 0x20000400,  LENGTH = 319K
 FLASH  (rx)  : ORIGIN = 0x8000000,  LENGTH = 1024K
}
 

and section for your special variables place to RAM0 ...

[Ecohe]

Thanks a lot.

[TDK]

CubeMX generates two LD (not ID) files, but only the *_FLASH.ld one is used by default.