arm-none-eabi-gcc (error: initializer element is not constant)

Question

I'm working through the book Embedded Systems Architecture by Daniele Lacamera. In Chapter 4, The Boot-Up Procedure, we create the Interrupt Vector Table (for an ARM Cortex M4) like this:

__attribute__ ((section(".isr_vector"))) void (* const ivt[])(void) =
{
    (void (*)(void))END_STACK,
    isr_reset,
    // Other ISRs
};

It wasn't shown how END_STACK was externed, so I did it like this:

extern uint32_t END_STACK;

The linker script is similar to the following:

MEMORY
{
    FLASH (rx) : ORIGIN = 0x00000000, LENGTH = 256K
    RAM (rwx) : ORIGIN = 0x20000000, LENGTH = 48K
}

END_STACK = ORIGIN(RAM) + LENGTH(RAM)

I'm getting the following error:

arm-none-eabi-gcc -c main.c interrupt_vector.c -O0 -g -mthumb -mcpu=cortex-m4 -ffreestanding
interrupt_vector.c:14:5: error: initializer element is not constant
     (void (*)(void))END_STACK,
     ^

What is a proper way to handle this? Is it possible to cast this to an address of a function or should I create a new section solely for the Stack Pointer?

I've tried sprinkling const in the extern and cast, but cannot resolve the error.

You need `&END_STACK`, linker is communicating via "addresses"., the symbols themselves have no values — Eugene Sh., May 15 '20 at 15:34
Check this for more info: https://stackoverflow.com/questions/8398755/access-symbols-defined-in-the-linker-script-by-application — Eugene Sh., May 15 '20 at 15:36

arm-none-eabi-gcc (error: initializer element is not constant)

0 Answers0