[Settings] Implement simple_settings backed with extensible DHCP options

src/core/settings.c

  ******************************************************************************
  */
 
-// Dummy routine just for testing
+/**
+ * Store value of simple setting
+ *
+ * @v options		DHCP option block
+ * @v tag		Setting tag number
+ * @v data		Setting data, or NULL to clear setting
+ * @v len		Length of setting data
+ * @ret rc		Return status code
+ */
 int simple_settings_store ( struct settings *settings, unsigned int tag,
 			    const void *data, size_t len ) {
-	DBGC ( settings, "Settings %p: store %s to:\n",
-	       settings, setting_tag_name ( tag ) );
-	DBGC_HD ( settings, data, len );
-	return 0;
+	struct simple_settings *simple =
+		container_of ( settings, struct simple_settings, settings );
+	return dhcpopt_extensible_store ( &simple->dhcpopts, tag, data, len );
 }
 
-// Dummy routine just for testing
+/**
+ * Fetch value of simple setting
+ *
+ * @v options		DHCP option block
+ * @v tag		Setting tag number
+ * @v data		Buffer to fill with setting data
+ * @v len		Length of buffer
+ * @ret len		Length of setting data, or negative error
+ */
 int simple_settings_fetch ( struct settings *settings, unsigned int tag,
 			    void *data, size_t len ) {
-	( void ) settings;
-	( void ) tag;
-	( void ) data;
-	( void ) len;
-	return -ENOENT;
+	struct simple_settings *simple =
+		container_of ( settings, struct simple_settings, settings );
+	return dhcpopt_fetch ( &simple->dhcpopts, tag, data, len );
 }
 
 /** Simple settings operations */
 	.fetch = simple_settings_fetch,
 };
 
-/** Root settings block */
-struct settings settings_root = {
-	.refcnt = NULL,
-	.name = "",
-	.siblings = LIST_HEAD_INIT ( settings_root.siblings ),
-	.children = LIST_HEAD_INIT ( settings_root.children ),
-	.op = &simple_settings_operations,
+/** Root simple settings block */
+struct simple_settings simple_settings_root = {
+	.settings = {
+		.refcnt = NULL,
+		.name = "",
+		.siblings =
+		     LIST_HEAD_INIT ( simple_settings_root.settings.siblings ),
+		.children =
+		     LIST_HEAD_INIT ( simple_settings_root.settings.children ),
+		.op = &simple_settings_operations,
+	},
 };
 
+/** Root settings block */
+#define settings_root simple_settings_root.settings
+
 /**
  * Apply all settings
  *

src/include/gpxe/netdevice.h

 	struct net_device_stats stats;
 
 	/** Configuration settings applicable to this device */
-	struct settings settings;
+	struct simple_settings settings;
 
 	/** Driver private data */
 	void *priv;
  */
 static inline __attribute__ (( always_inline )) struct settings *
 netdev_settings ( struct net_device *netdev ) {
-	return &netdev->settings;
+	return &netdev->settings.settings;
 }
 
 extern int netdev_tx ( struct net_device *netdev, struct io_buffer *iobuf );

src/include/gpxe/settings.h

 #include <gpxe/tables.h>
 #include <gpxe/list.h>
 #include <gpxe/refcnt.h>
+#include <gpxe/dhcpopts.h>
 
 struct settings;
 struct in_addr;
 #define __settings_applicator \
 	__table ( struct settings_applicator, settings_applicators, 01 )
 
+/**
+ * A simple settings block
+ *
+ */
+struct simple_settings {
+	/** Settings block */
+	struct settings settings;
+	/** DHCP options */
+	struct dhcp_options dhcpopts;
+};
+
+extern struct settings_operations simple_settings_operations;
+
 extern int simple_settings_store ( struct settings *settings, unsigned int tag,
 				   const void *data, size_t len );
 extern int simple_settings_fetch ( struct settings *settings, unsigned int tag,
 				   void *data, size_t len );
-extern struct settings_operations simple_settings_operations;
-
 extern int register_settings ( struct settings *settings,
 			       struct settings *parent );
 extern void unregister_settings ( struct settings *settings );
 	settings->name = name;
 }
 
+/**
+ * Initialise a settings block
+ *
+ * @v simple		Simple settings block
+ * @v refcnt		Containing object reference counter, or NULL
+ * @v name		Settings block name
+ */
+static inline void simple_settings_init ( struct simple_settings *simple,
+					  struct refcnt *refcnt,
+					  const char *name ) {
+	settings_init ( &simple->settings, &simple_settings_operations,
+			refcnt, name );
+}
+
 /**
  * Delete setting
  *

src/net/netdev_settings.c

  */
 static int netdev_store ( struct settings *settings, unsigned int tag,
 			  const void *data, size_t len ) {
-	struct net_device *netdev =
-		container_of ( settings, struct net_device, settings );
+	struct net_device *netdev = container_of ( settings, struct net_device,
+						   settings.settings );
 
 	switch ( tag ) {
 	case DHCP_EB_MAC:
  */
 static int netdev_fetch ( struct settings *settings, unsigned int tag,
 			  void *data, size_t len ) {
-	struct net_device *netdev =
-		container_of ( settings, struct net_device, settings );
+	struct net_device *netdev = container_of ( settings, struct net_device,
+						   settings.settings );
 
 	switch ( tag ) {
 	case DHCP_EB_MAC: