This routine does not appear to be used anywhere.

Index: sys/net/if.c
===================================================================
RCS file: /OpenBSD/src/sys/net/if.c,v
diff -u -p -u -p -r1.765 if.c
--- sys/net/if.c	16 Sep 2026 06:18:35 -0000	1.765
+++ sys/net/if.c	20 Sep 2026 16:47:44 -0000
@@ -707,21 +707,6 @@ if_attach_common(struct ifnet *ifp)
 }
 
 void
-if_attach_ifq(struct ifnet *ifp, const struct ifq_ops *newops, void *args)
-{
-	/*
-	 * only switch the ifq_ops on the first ifq on an interface.
-	 *
-	 * the only ifq_ops we provide priq and hfsc, and hfsc only
-	 * works on a single ifq. because the code uses the ifq_ops
-	 * on the first ifq (if_snd) to select a queue for an mbuf,
-	 * by switching only the first one we change both the algorithm
-	 * and force the routing of all new packets to it.
-	 */
-	ifq_attach(&ifp->if_snd, newops, args);
-}
-
-void
 if_start(struct ifnet *ifp)
 {
 	KASSERT(ifp->if_qstart == if_qstart_compat);
Index: sys/net/if.h
===================================================================
RCS file: /OpenBSD/src/sys/net/if.h,v
diff -u -p -u -p -r1.224 if.h
--- sys/net/if.h	23 Jun 2026 14:40:40 -0000	1.224
+++ sys/net/if.h	20 Sep 2026 16:47:44 -0000
@@ -539,7 +539,6 @@ void	if_free_sadl(struct ifnet *);
 void	if_attach(struct ifnet *);
 void	if_attach_queues(struct ifnet *, unsigned int);
 void	if_attach_iqueues(struct ifnet *, unsigned int);
-void	if_attach_ifq(struct ifnet *, const struct ifq_ops *, void *);
 void	if_attachhead(struct ifnet *);
 void	if_deactivate(struct ifnet *);
 void	if_detach(struct ifnet *);