OS X and iOS map in __TEXT,__PAGEZERO to 0x0.* Of course, it is mapped without any protection levels so it isn&#x27;t of much use except for catching most nullptr dereferences (just 4 GB of protection on x86_64!).<p>* Well, this is implemented by the default system toolchain. You&#x27;r particular toolchain can opt out of this behavior if they want to.