lguest: documentation I: Preparation

The netfilter code had very good documentation: the Netfilter Hacking HOWTO.
Noone ever read it.

So this time I'm trying something different, using a bit of Knuthiness.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/lguest/hypercalls.c b/drivers/lguest/hypercalls.c
index ea52ca4..fb546b0 100644
--- a/drivers/lguest/hypercalls.c
+++ b/drivers/lguest/hypercalls.c
@@ -1,5 +1,10 @@
-/*  Actual hypercalls, which allow guests to actually do something.
-    Copyright (C) 2006 Rusty Russell IBM Corporation
+/*P:500 Just as userspace programs request kernel operations through a system
+ * call, the Guest requests Host operations through a "hypercall".  You might
+ * notice this nomenclature doesn't really follow any logic, but the name has
+ * been around for long enough that we're stuck with it.  As you'd expect, this
+ * code is basically a one big switch statement. :*/
+
+/*  Copyright (C) 2006 Rusty Russell IBM Corporation
 
     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by