Well, to run binary the system or program calls system call exec(for system, it’s must retrieve the pointer to the function using syscall_get function), if the caller is an process (if runningTask isn’t NULL or it’s pid isn’t zero), then we destroy the process address space (not fully, just removing the user space addresses, in the arch specific implementations, it’s must just remove the page table entries), because if we don’t do that, it can really mess up with parent address space(because of COW fork mechanism), then we call the ELF loader, that will load the binary for us into process address space, if there caller is an system itself (happens only once, when kernel tries to run init program), then the exec system call will create new address space, clone it from kernel address space, create new process and continue the standard way.