How can I make an empty section with GNU ld? - ld

Question

I'm working on a cortex-m3 chip. The stack space was reserved in the source code with an uninitialized array on the bss section. The linker script I used is as follows:
MEMORY
{
FLASH (rx) : ORIGIN = 0x00000000, LENGTH = 256k
SRAM (rwx) : ORIGIN = 0x20000000, LENGTH = 64k
}
SECTIONS {
.text : {
KEEP(*(.isr_vector))
*(.text*)
*(.rodata*)
__text_end = .;
} >FLASH
.data : {
__data_start = .;
*(.data*)
__data_end = .;
} >SRAM AT>FLASH
.bss : {
__bss_start = .;
*(.bss*)
__bss_end = .;
} >SRAM
}
I'm trying to allocate a section for the stack in the beginning of the SRAM region so that i could detect stack overflow with usage fault.
I added a section named .stack:
SECTIONS {
.text : {
:
} >FLASH
.stack : {
__stack_size = 4k;
__stack_start = .;
. = . + __stack_size;
. = ALIGN(8); /* cortex-m3 uses full-descending stack aligned with 8 bytes */
__stack_end = .;
} >SRAM
.data : {
:
} >SRAM AT>FLASH
.bss : {
:
} >SRAM
}
Linking is done without any error or warning, but the problem is that __stack_end is not on the SRAM region but on the FLASH region.
I know I can use a separate section given with __attribute__((section("name"))) but I think it would be better if I can deal with it in the linker script.
How can I make an empty section on SRAM region?

Answer 1

Just split the RAM area in two:
MEMORY
{
FLASH (rx) : ORIGIN = 0x00000000, LENGTH = 256k
SRAM_STACK (rwx) : ORIGIN = 0x20000000, LENGTH = 4k
SRAM (rwx) : ORIGIN = 0x20001000, LENGTH = 60k
}
SECTIONS {
.text : {
KEEP(*(.isr_vector))
*(.text*)
*(.rodata*)
__text_end = .;
} >FLASH
.data : {
__data_start = .;
*(.data*)
__data_end = .;
} >SRAM AT>FLASH
.bss : {
__bss_start = .;
*(.bss*)
__bss_end = .;
} >SRAM
.stack : {
__stack_size = 4k;
__stack_start = .;
. = . + __stack_size;
. = ALIGN(8); /* cortex-m3 uses full-descending stack aligned with 8 bytes */
__stack_end = .;
} >SRAM_STACK
}