Index: sys/sys/systm.h
===================================================================
--- sys/sys/systm.h
+++ sys/sys/systm.h
@@ -669,6 +669,12 @@
 #define	__diagused	__unused
 #endif
 
+#ifdef SMP
+#define __smpused
+#else
+#define __smpused	__unused
+#endif
+
 #endif /* _KERNEL */
 
 __NULLABILITY_PRAGMA_POP