+/* Random value for struct thread's `magic' member.
+ Used to detect stack overflow. See the big comment at the top
+ of thread.h for details. */
+#define THREAD_MAGIC 0xcd6abf4b
+
+/* List of processes in THREAD_READY state, that is, processes
+ that are ready to run but not actually running. */
+static struct list ready_list;
+
+/* Idle thread. */
+static struct thread *idle_thread;
+
+/* Initial thread, the thread running init.c:main(). */
+static struct thread *initial_thread;
+
+/* Lock used by allocate_tid(). */
+static struct lock tid_lock;
+
+/* Stack frame for kernel_thread(). */
+struct kernel_thread_frame
+ {
+ void *eip; /* Return address. */
+ thread_func *function; /* Function to call. */
+ void *aux; /* Auxiliary data for function. */
+ };
+
+static void kernel_thread (thread_func *, void *aux);
+
+static void idle (void *aux UNUSED);
+static struct thread *running_thread (void);
+static struct thread *next_thread_to_run (void);
+static struct thread *new_thread (const char *name, int priority);
+static void init_thread (struct thread *, const char *name, int priority);
+static bool is_thread (struct thread *);
+static void *alloc_frame (struct thread *, size_t size);
+static void destroy_thread (struct thread *);
+static void schedule (void);
+void schedule_tail (struct thread *prev);
+static tid_t allocate_tid (void);
+
+/* Initializes the threading system by transforming the code
+ that's currently running into a thread. Note that this is
+ possible only because the loader was careful to put the bottom
+ of the stack at a page boundary; it won't work in general.
+ Also initializes the run queue.
+
+ After calling this function, be sure to initialize the page
+ allocator before trying to create any threads with
+ thread_create(). */