+#ifdef CONFIG_REGEX
+#define ENV_DOT_ESCAPE "\\"
+#else
+#define ENV_DOT_ESCAPE
+#endif
+
+#ifdef CONFIG_CMD_DNS
+#define DNS_CALLBACK "dnsip:dnsip,"
+#else
+#define DNS_CALLBACK
+#endif
+
+#ifdef CONFIG_NET
+#define NET_CALLBACKS \
+ "bootfile:bootfile," \
+ "ipaddr:ipaddr," \
+ "gatewayip:gatewayip," \
+ "netmask:netmask," \
+ "serverip:serverip," \
+ "nvlan:nvlan," \
+ "vlan:vlan," \
+ DNS_CALLBACK \
+ "eth\\d?addr:ethaddr,"
+#else
+#define NET_CALLBACKS
+#endif
+