Changes in the README, changes to fork template.

tasks/mm0/src/clone.c

@@ -3,7 +3,7 @@
  *
  * Copyright (C) 2008 Bahadir Balban
  */
-
+#include <syscalls.h>
 
 int copy_tcb(struct tcb *p, struct tcb *c)
 {
@@ -28,20 +28,33 @@ int do_fork(struct tcb *parent)
 {
 	struct tcb *child;
 
+	/* Make all parent shadows read only */
+	vm_freeze_shadows(parent);
+
 	/* 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 ??? */
+	/*
+	 * Allocate and copy parent pgd + all pmds to child.
+	 *
+	 * When a write fault occurs on any of the frozen shadows,
+	 * fault handler creates a new shadow on top, if it hasn't,
+	 * and then starts adding writeable pages to the new shadow.
+	 * Every forked task will fault on every page of the frozen shadow,
+	 * until all pages have been made copy-on-write'ed, in which case
+	 * the underlying frozen shadow is collapsed.
+	 *
+	 * Every forked task must have its own copy of pgd + pmds because
+	 * every one of them will have to fault on frozen shadows individually.
+	 */
+
+	/* FIXME: Need to copy parent register values to child ??? */
 
 	/* Notify fs0 about forked process */
 	vfs_send_fork(parent, child);