diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h
index 7800cce..4dff0c6 100644
--- a/include/linux/kgdb.h
+++ b/include/linux/kgdb.h
@@ -286,6 +286,16 @@
 
 extern unsigned long __weak kgdb_arch_pc(int exception, struct pt_regs *regs);
 
+#ifdef CONFIG_SERIAL_KGDB_NMI
+extern int kgdb_register_nmi_console(void);
+extern int kgdb_unregister_nmi_console(void);
+extern bool kgdb_nmi_poll_knock(void);
+#else
+static inline int kgdb_register_nmi_console(void) { return 0; }
+static inline int kgdb_unregister_nmi_console(void) { return 0; }
+static inline bool kgdb_nmi_poll_knock(void) { return 1; }
+#endif
+
 extern int kgdb_register_io_module(struct kgdb_io *local_kgdb_io_ops);
 extern void kgdb_unregister_io_module(struct kgdb_io *local_kgdb_io_ops);
 extern struct kgdb_io *dbg_io_ops;