diff --git a/include/common/debug.h b/include/common/debug.h
index 3f5655b..a8dcb8d 100644
--- a/include/common/debug.h
+++ b/include/common/debug.h
@@ -33,24 +33,53 @@
 
 #include <stdio.h>
 
-/* If building the project with DEBUG disabled the INFO and WARN macros
- * won't produce any output. The ERROR macro is always enabled.
- * The format expected is the same as for printf().
- * INFO("Info %s.\n", "message")    -> INFO: Info message.
- * WARN("Warning %s.\n", "message") -> WARN: Warning message.
- * ERROR("Error %s.\n", "message")  -> ERROR: Error message.
- *
- * TODO : add debug levels.
+/* The log output macros print output to the console. These macros produce
+ * compiled log output only if the LOG_LEVEL defined in the makefile (or the
+ * make command line) is greater or equal than the level required for that
+ * type of log output.
+ * The format expected is the same as for printf(). For example:
+ * INFO("Info %s.\n", "message")    -> INFO:    Info message.
+ * WARN("Warning %s.\n", "message") -> WARNING: Warning message.
  */
-#if DEBUG
- #define INFO(...)	tf_printf("INFO: " __VA_ARGS__)
- #define WARN(...)	tf_printf("WARN: " __VA_ARGS__)
+
+#define LOG_LEVEL_NONE			0
+#define LOG_LEVEL_ERROR			10
+#define LOG_LEVEL_NOTICE		20
+#define LOG_LEVEL_WARNING		30
+#define LOG_LEVEL_INFO			40
+#define LOG_LEVEL_VERBOSE		50
+
+
+#if LOG_LEVEL >= LOG_LEVEL_NOTICE
+# define NOTICE(...)	tf_printf("NOTICE:  " __VA_ARGS__)
 #else
- #define INFO(...)
- #define WARN(...)
+# define NOTICE(...)
 #endif
 
-#define ERROR(...)	tf_printf("ERROR: " __VA_ARGS__)
+#if LOG_LEVEL >= LOG_LEVEL_ERROR
+# define ERROR(...)	tf_printf("ERROR:   " __VA_ARGS__)
+#else
+# define ERROR(...)
+#endif
+
+#if LOG_LEVEL >= LOG_LEVEL_WARNING
+# define WARN(...)	tf_printf("WARNING: " __VA_ARGS__)
+#else
+# define WARN(...)
+#endif
+
+#if LOG_LEVEL >= LOG_LEVEL_INFO
+# define INFO(...)	tf_printf("INFO:    " __VA_ARGS__)
+#else
+# define INFO(...)
+#endif
+
+#if LOG_LEVEL >= LOG_LEVEL_VERBOSE
+# define VERBOSE(...)	tf_printf("VERBOSE: " __VA_ARGS__)
+#else
+# define VERBOSE(...)
+#endif
+
 
 void __dead2 do_panic(void);
 #define panic()	do_panic()