Add on-boot instrumentation support for note filter

drivers/note/Kconfig

@@ -55,6 +55,15 @@ config DRIVER_NOTERAM_BUFSIZE
 	---help---
 		The size of the in-memory, circular instrumentation buffer (in bytes).
 
+config DRIVER_NOTERAM_DEFAULT_NOOVERWRITE
+	bool "Disable overwrite by default"
+	depends on DRIVER_NOTERAM
+	default n
+	---help---
+		Disables overwriting old notes in the circular buffer when the buffer
+		is full by default. This is useful to keep instrumentation data of the
+		beginning of a system boot.
+
 config DRIVER_NOTECTL
 	bool "Scheduler instrumentation filter control driver"
 	default n

drivers/note/noteram_driver.c

@@ -92,7 +92,11 @@ static const struct file_operations g_noteram_fops =
 
 static struct noteram_info_s g_noteram_info =
 {
+#ifdef CONFIG_DRIVER_NOTERAM_DEFAULT_NOOVERWRITE
+  .ni_overwrite = NOTERAM_MODE_OVERWRITE_DISABLE
+#else
   .ni_overwrite = NOTERAM_MODE_OVERWRITE_ENABLE
+#endif
 };
 
 #ifdef CONFIG_SMP