Changes towards adding clone/fork

new file:   src/clone.c

tasks/mm0/src/clone.c

@@ -0,0 +1,57 @@
+/*
+ * Forking and cloning threads, processes
+ *
+ * Copyright (C) 2008 Bahadir Balban
+ */
+
+
+int copy_tcb(struct tcb *p, struct tcb *c)
+{
+	/* Copy program segments, file descriptors, vm areas */
+}
+
+/*
+ * Sets all r/w shadow objects as read-only for the process
+ * so that copy-on-write incidents cause read faults.
+ */
+int vm_freeze_shadows(struct tcb *t)
+{
+	/* Make all shadows read-only */
+
+	/*
+	 * Make all writeable shadow entries
+	 * in the page table as read-only
+	 */
+}
+
+int do_fork(struct tcb *parent)
+{
+	struct tcb *child;
+
+	/* Create a new L4 thread with new space */
+	l4_thread_create(parent);
+
+	/* Create a new local tcb */
+	child = tcb_alloc_init();
+
+	/* Make all parent shadows read only */
+	vm_freeze_shadows(parent);
+
+	/* Copy parent tcb to child */
+	copy_tcb(struct tcb *parent, struct tcb *child);
+
+	/* FIXME: Copy parent page tables to child ??? */
+	/* FIXME: Copy parent register values to child ??? */
+
+	/* Notify fs0 about forked process */
+	vfs_send_fork(parent, child);
+
+	/* Start forked child */
+	l4_thread_start(child);
+
+	/* Return back to parent */
+	l4_ipc_return(0);
+
+	return 0;
+}
+