Should ALL global variables be volatile-qualified?

Question

In this example, does correctness require global_value to be declared volatile?

int global_value = 0;

void foo () {
    ++ global_v         


        

Answer 1

The only uses of volatile involve longjmp, signal handlers, memory-mapped device drivers, and writing your own low-level multi-threaded synchronization primitives. For this last use however, volatile is not sufficient and may not even be necessary. You'll definitely also need asm (or compiler-specific or C1x atomics) for synchronization.

volatile is not useful for any other purposes, including the code you asked about.