Somewhat newb question about assy and the heap.
- by Eric M
Ultimately I am just trying to figure out how to dynamically allocate heap memory from within assembly.
If I call Linux sbrk() from assembly code, can I use the address returned as I would use an address of a statically (ie in the .data section of my program listing) declared chunk of memory?
I know Linux uses the hardware MMU if present, so I am not sure if what sbrk returns is a 'raw' pointer to real RAM, or is it a cooked pointer to RAM that may be modified by Linux's VM system?
I read this: How are sbrk/brk implemented in Linux?. I suspect I can not use the return value from sbrk() without worry: the MMU fault on access-non-allocated-address must cause the VM to alter the real location in RAM being addressed. Thus assy, not linked against libc or what-have-you, would not know the address has changed.
Does this make sense, or am I out to lunch?