--- zzzz-none-000/linux-3.10.107/include/linux/pvclock_gtod.h	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/include/linux/pvclock_gtod.h	2021-02-04 17:41:59.000000000 +0000
@@ -3,6 +3,13 @@
 
 #include <linux/notifier.h>
 
+/*
+ * The pvclock gtod notifier is called when the system time is updated
+ * and is used to keep guest time synchronized with host time.
+ *
+ * The 'action' parameter in the notifier function is false (0), or
+ * true (non-zero) if system time was stepped.
+ */
 extern int pvclock_gtod_register_notifier(struct notifier_block *nb);
 extern int pvclock_gtod_unregister_notifier(struct notifier_block *nb);