Remove some assumptions about DHCP obtaining only a single options block.

src/include/gpxe/dhcp.h

 	ref_put ( &options->refcnt );
 }
 
+extern struct list_head dhcp_option_blocks;
+
 extern unsigned long dhcp_num_option ( struct dhcp_option *option );
 extern void dhcp_ipv4_option ( struct dhcp_option *option,
 			       struct in_addr *inp );

src/net/dhcpopts.c

  */
 
 /** List of registered DHCP option blocks */
-static LIST_HEAD ( option_blocks );
+LIST_HEAD ( dhcp_option_blocks );
 
 /** Registered DHCP option applicators */
 static struct dhcp_option_applicator dhcp_option_applicators[0]
 	if ( options ) {
 		return find_dhcp_option_with_encap ( options, tag, NULL );
 	} else {
-		list_for_each_entry ( options, &option_blocks, list ) {
+		list_for_each_entry ( options, &dhcp_option_blocks, list ) {
 			if ( ( option = find_dhcp_option ( options, tag ) ) )
 				return option;
 		}
 	      options, options->priority );
 
 	/* Insert after any existing blocks which have a higher priority */
-	list_for_each_entry ( existing, &option_blocks, list ) {
+	list_for_each_entry ( existing, &dhcp_option_blocks, list ) {
 		if ( options->priority > existing->priority )
 			break;
 	}

src/net/udp/dhcp.c

 	struct in_addr gateway = { INADDR_NONE };
 	int rc;
 
-	/* Clear any existing routing table entry */
-	del_ipv4_address ( netdev );
-
 	/* Retrieve IP address configuration */
 	find_dhcp_ipv4_option ( options, DHCP_EB_YIADDR, &address );
 	find_dhcp_ipv4_option ( options, DHCP_SUBNET_MASK, &netmask );
 	find_dhcp_ipv4_option ( options, DHCP_ROUTERS, &gateway );
 
+	/* Do nothing unless we have at least an IP address to use */
+	if ( ! address.s_addr )
+		return 0;
+
+	/* Clear any existing routing table entry */
+	del_ipv4_address ( netdev );
+
 	/* Set up new IP address configuration */
 	if ( ( rc = add_ipv4_address ( netdev, address, netmask,
 				       gateway ) ) != 0 ) {

src/usr/dhcpmgmt.c

  *
  */
 
-static struct dhcp_option_block *dhcp_options = NULL;
-
 static int dhcp_success ( struct net_device *netdev,
 			  struct dhcp_option_block *options ) {
-	dhcp_options = dhcpopt_get ( options );
+	DBGC ( options, "DHCP client registering options %p\n", options );
 	register_dhcp_options ( options );
 	return dhcp_configure_netdev ( netdev, options );
 }
 
 int dhcp ( struct net_device *netdev ) {
+	struct dhcp_option_block *options;
+	struct dhcp_option_block *tmp;
 	int rc;
 
 	/* Check we can open the interface first */
 	if ( ( rc = ifopen ( netdev ) ) != 0 )
 		return rc;
 
-	/* Unregister any previously acquired options */
-	if ( dhcp_options ) {
-		unregister_dhcp_options ( dhcp_options );
-		dhcpopt_put ( dhcp_options );
-		dhcp_options = NULL;
+	/* Unregister any option blocks acquired via DHCP */
+	list_for_each_entry_safe ( options, tmp, &dhcp_option_blocks, list ) {
+		/* Skip static option blocks (e.g. from NVS) */
+		if ( find_dhcp_option ( options, DHCP_MESSAGE_TYPE ) ) {
+			DBGC ( options, "DHCP client unregistering options "
+			       "%p\n", options );
+			unregister_dhcp_options ( options );
+		}
 	}
 
 	/* Perform DHCP */