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

Question

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?

Answer 1

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:
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