I’m working on an embedded project using an ARM Cortex-M4 processor (specifically, an STM32F4 microcontroller) and I’ve encountered a peculiar issue related to memory sections defined in my linker script. I’m using the arm-none-eabi-gcc toolchain for compilation.

I have a binary file that I want to include in my firmware. I’ve created a custom section (.rawdata) in my assembly file to include this binary file, and I’ve modified my linker script to place this section in the Flash memory. However, I’m facing an issue with the integrity of the data in the .rawdata section during runtime.

When I place the .rawdata section within the .data section or in the .text section in my linker script, everything works as expected: the data is correctly allocated in memory, and the actual data is stored correctly. I can access and print the data during runtime without any issues.

However, when I try to create a standalone .rawdata section (outside of .data) or place it within the .text section, the data seems to be allocated, but the content is not what I expect. During runtime, when I print the content of the .rawdata section, I get incorrect values (not matching the original .bin content).
Interestingly, when I inspect the .elf file using arm-none-eabi-objdump, the .rawdata section appears to contain the correct data. This discrepancy only occurs during runtime.

Linker Script Snippet:

ld
.rawdata :
{
  . = ALIGN(4);
  _mstart = .;
  KEEP(*(.rawdata))
  . = ALIGN(4);
  _mend = .;
} >FLASH

Why does placing the .rawdata section inside the .data section work correctly, but creating it as a standalone section leads to incorrect runtime data?
Is there a specific consideration or configuration I’m missing for custom sections in the linker script for ARM Cortex-M4 processors?

How can I ensure that the .rawdata section’s data remains intact during runtime when it’s defined outside the .data section?

Any insights or suggestions on how to resolve this issue would be greatly appreciated. Thank you in advance for your help!