Lots of stuff on macOS gone weird / mental. Try to set thread affinity, for example. Look at their source in /usr/include/mach/thread_policy.h under thread_policy_set and thread_policy_get
Lots of stuff on macOS gone weird / mental. Try to allocate large blocks of memory in a dynamically loaded function. The pointer you get back is a raw non-virtual pointer, then you need to use non-posix calls to map that region into your process's virtual memory space.
Are you saying that when you call dlsym(3) on OS X you get back a non-null pointer to memory that is not mapped inside your address space? That can't be, right? So where does your "weird" pointer actually come from and how is it connected to the allocation of huge blocks?