OS X and iOS Kernel Programming

Process Address Spaces

Although there are typically many processes running at any one time, each process is unaware of the other processes running on the system. In fact, without explicit code, one process cannot interact or influence the behavior of another process.

The operating system provides each process with a range of memory within which it is allowed to operate; this is known as the process's address space. The address space is dynamic and changes during execution as a process allocates memory. If a process attempts to read or write to a memory address outside of its address space, the operating system typically terminates it, and the user informed that the application has crashed.

Although protected memory is not new, it is only within ...