The difference is that with $
it’s the numeric value while without $
it’s the contents of memory at that address
If argument of instruction is without any special marker (such as % for register or $ for numeric constant), then it is memory access. So following:
movl 10, %eax movl foo, %eax
Corresponds to intel syntax:
mov eax, [10] mov eax, [foo]
To use numeric constant, or use address of label, there is $ operator:
movl $10, %eax movl $foo, %eax
In Intel syntax:
mov eax, 10 mov eax, offset foo