diff --git a/sys/arm/arm/busdma_machdep.c b/sys/arm/arm/busdma_machdep.c
--- a/sys/arm/arm/busdma_machdep.c
+++ b/sys/arm/arm/busdma_machdep.c
@@ -398,6 +398,10 @@
 	/* Return a NULL tag on failure */
 	*dmat = NULL;
 
+	/* Filters are deprecated, emit a warning. */
+	if (filter != NULL || filterarg != NULL)
+		printf("Warning: use of filters is deprecated; see busdma(9)\n");
+
 	newtag = (bus_dma_tag_t)malloc(sizeof(*newtag), M_BUSDMA,
 	    M_ZERO | M_NOWAIT);
 	if (newtag == NULL) {
diff --git a/sys/arm64/arm64/busdma_machdep.c b/sys/arm64/arm64/busdma_machdep.c
--- a/sys/arm64/arm64/busdma_machdep.c
+++ b/sys/arm64/arm64/busdma_machdep.c
@@ -161,6 +161,10 @@
 	struct bus_dma_tag_common *tc;
 	int error;
 
+	/* Filters are deprecated, emit a warning. */
+	if (filter != NULL || filterarg != NULL)
+		printf("Warning: use of filters is deprecated; see busdma(9)\n");
+
 	if (parent == NULL) {
 		error = bus_dma_bounce_impl.tag_create(parent, alignment,
 		    boundary, lowaddr, highaddr, filter, filterarg, maxsize,
diff --git a/sys/powerpc/powerpc/busdma_machdep.c b/sys/powerpc/powerpc/busdma_machdep.c
--- a/sys/powerpc/powerpc/busdma_machdep.c
+++ b/sys/powerpc/powerpc/busdma_machdep.c
@@ -168,6 +168,10 @@
 		return (EINVAL);
 	}
 
+	/* Filters are deprecated, emit a warning. */
+	if (filter != NULL || filterarg != NULL)
+		printf("Warning: use of filters is deprecated; see busdma(9)\n");
+
 	/* Return a NULL tag on failure */
 	*dmat = NULL;
 
diff --git a/sys/riscv/riscv/busdma_machdep.c b/sys/riscv/riscv/busdma_machdep.c
--- a/sys/riscv/riscv/busdma_machdep.c
+++ b/sys/riscv/riscv/busdma_machdep.c
@@ -162,6 +162,10 @@
 	struct bus_dma_tag_common *tc;
 	int error;
 
+	/* Filters are deprecated, emit a warning. */
+	if (filter != NULL || filterarg != NULL)
+		printf("Warning: use of filters is deprecated; see busdma(9)\n");
+
 	if (parent == NULL) {
 		error = bus_dma_bounce_impl.tag_create(parent, alignment,
 		    boundary, lowaddr, highaddr, filter, filterarg, maxsize,
diff --git a/sys/x86/x86/busdma_machdep.c b/sys/x86/x86/busdma_machdep.c
--- a/sys/x86/x86/busdma_machdep.c
+++ b/sys/x86/x86/busdma_machdep.c
@@ -184,6 +184,10 @@
 	struct bus_dma_tag_common *tc;
 	int error;
 
+	/* Filters are deprecated, emit a warning. */
+	if (filter != NULL || filterarg != NULL)
+		printf("Warning: use of filters is deprecated; see busdma(9)\n");
+
 	if (parent == NULL) {
 		error = bus_dma_bounce_impl.tag_create(parent, alignment,
 		    boundary, lowaddr, highaddr, filter, filterarg, maxsize,