GCC Linker - Locate a section/constant at a specific address within the .text section

I would like to locate a 32bit constant value at a specific address (0x080017FC) within the .text (code) section.

To be honest, when it comes to modifying the linker script to this extent I'm naïve and feel like I do not have a clue what to do.

I've modified my linker script to contain this new section (.systemid) within the .text section.

  .text :
  {    
    . = ALIGN(4);
    KEEP(*(.systemid))
    *(.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

To ensure it does not get optimized away, I used KEEP.

I then declared my constant in the new section (.systemid). This is where I start to wonder what am I supposed to do. If .systemid was a section on its own, I would have declared the constant as follows:

const uint32_t __attribute__((used, section (".systemid"))) SYSTEM_ID_U32 = 0x11223344;

But since this is a section within a section, should it not be?:

uint32_t __attribute__((used, section (".text.systemid"))) SYSTEM_ID_U32 = 0x11223344;

So the linker will locate the constant at the beginning of the .text section (0x000001A0). Great, it is inside the text section but not at the correct address. I would like to locate the constant at 0x08001F7C.

To try and achieve this, I pass the following to the linker:

 -Wl,--section-start=.text.systemid=0x080017FC

Again I'm not sure if it should be .systemid or .text.systemid

Either way, it does not locate the constant at 0x080017FC

How do I get my constant to be located at 0x080017FC within the .text (code) section without any overlap errors?

It will not work this way. There is no way I am aware of placing section at the particular address without problems from the linker if it is part of another section. Linker is quite a simple program and will not optimize the memory to avoid your location.

I use two methods:

1. Place this id at the end of the FLASH. You cant do this at the beginning as there is the vector table.

const uint32_t __attribute__((used, section (".systemid"))) SYSTEM_ID_U32 = 0x11223344;

Place after all other sections in FLASH (it can be the last section definition

  .systemid :
  {
    . = ORIGIN(FLASH) + LENGTH(FLASH) - 4;
    KEEP(*(.systemid))
  } >FLASH

or

  .systemid ORIGIN(FLASH) + LENGTH(FLASH) - 4:
  {
    KEEP(*(.systemid))
  } >FLASH