Wrong base address for XSPI2 hex file - what exactly decides it ?

[simo zz]

Hi, 

I am using an STM32H7RS3x device with external QSPI flash connected to XSPI2 interface with address = 0x7000_0000.

I have noticed that the base address of from the hexfile I have to flash into external XSPI (of course using external loader) is not 0x7000_0000 but 0x2407_1c00, which is, curiously, the address of the NONCACHEABLE RAM.

What decides the the base address of the hex file? What comes into play on this decision?

To add some information, this is the linker script I am using for the XSPI2 (stm32h7rsxx_ROMxspi2.ld : 

/*
******************************************************************************
**
** @file        : LinkerScript.ld
**
** @author      : STM32CubeIDE
**
**  Abstract    : Linker script for STM32H7Rxx8 Device
**                      64Kbytes FLASH
**                      456Kbytes 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) 2023 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(DTCM) + LENGTH(DTCM); /* end of "DTCM" Ram type memory */

_Min_Heap_Size = 0x400;      /* required amount of heap  */
_Min_Stack_Size = 0x400; /* required amount of stack */

__FLASH_BEGIN  = 0x70000000;
__FLASH_SIZE   = 0x08000000;

__RAM          = 0x24000000;
__RAM_SIZE     = 0x72000;
__RAM_NONCACHEABLEBUFFER_SIZE = 0x400;

/* Memories definition */
MEMORY
{
  RAM           (xrw) : ORIGIN = __RAM,    LENGTH = __RAM_SIZE -__RAM_NONCACHEABLEBUFFER_SIZE
  RAM_NONCACHEABLEBUFFER (xrw) : ORIGIN = __RAM + __RAM_SIZE - __RAM_NONCACHEABLEBUFFER_SIZE,  LENGTH = __RAM_NONCACHEABLEBUFFER_SIZE
  ITCM          (rw)  : ORIGIN = 0x00000000,  LENGTH = 0x00010000
  DTCM          (xrw) : ORIGIN = 0x20000000,  LENGTH = 0x00010000
  SRAMAHB       (rw)  : ORIGIN = 0x30000000,  LENGTH = 0x00008000
  BKPSRAM       (rw)  : ORIGIN = 0x38800000,  LENGTH = 0x00001000
  FLASH         (xrw) : ORIGIN = __FLASH_BEGIN, LENGTH = __FLASH_SIZE
}

/* 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 (READONLY) :
  {
    . = ALIGN(4);
    *(.ARM.extab* .gnu.linkonce.armextab.*)
    . = ALIGN(4);
  } >FLASH

  .ARM (READONLY) :
  {
    . = ALIGN(4);
    __exidx_start = .;
    *(.ARM.exidx*)
    __exidx_end = .;
    . = ALIGN(4);
  } >FLASH

  .preinit_array (READONLY) :
  {
    . = ALIGN(4);
    PROVIDE_HIDDEN (__preinit_array_start = .);
    KEEP (*(.preinit_array*))
    PROVIDE_HIDDEN (__preinit_array_end = .);
    . = ALIGN(4);
  } >FLASH

  .init_array (READONLY) :
  {
    . = ALIGN(4);
    PROVIDE_HIDDEN (__init_array_start = .);
    KEEP (*(SORT(.init_array.*)))
    KEEP (*(.init_array*))
    PROVIDE_HIDDEN (__init_array_end = .);
    . = ALIGN(4);
  } >FLASH

  .fini_array (READONLY) :
  {
    . = 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

  RW_NONCACHEABLE :
  {
    __NONCACHEABLEBUFFER_BEGIN = .;/* create symbol for start of section */
    KEEP(*(noncacheable_buffer))
    __NONCACHEABLEBUFFER_END = .;  /* create symbol for start of section */
  } > RAM_NONCACHEABLEBUFFER

  /* 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);
  } >DTCM

  /* Remove information from the compiler libraries */
  /DISCARD/ :
  {
    libc.a ( * )
    libm.a ( * )
    libgcc.a ( * )
  }

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

I have an example project using this linker script file correctly resulting in start address 0x7000_0000, but using on another (bigger) project results in start address 0x2407_1c00.

It seems that something else is influencing the linker script.

Makefile flags are not changed from project to project..

s.

[simo zz]

OK, what is causing this issue is the declaration of two buffers (used by DMA) as to be placed in NONCACHEABLE RAM section:

uint8_t __attribute__((section("noncacheable_buffer"))) cdcIBuff[512];
uint8_t __attribute__((section("noncacheable_buffer"))) cdcOBuff[512];

is there a way of avoiding the OP behavior keeping buffers into NONCACHEABLE RAM section ?

Thanks,

s.