--- a/buildrump.sh/src/sys/rump/dev/lib/libpci/rumpdev_bus_dma.c
+++ b/buildrump.sh/src/sys/rump/dev/lib/libpci/rumpdev_bus_dma.c
@@ -85,6 +85,8 @@
 static int	_bus_dmamap_load_buffer (bus_dma_tag_t, bus_dmamap_t, void *,
 	    bus_size_t, struct vmspace *, int, bus_addr_t *, int *, int);
 
+int bus_dmatag_subregion(bus_dma_tag_t tag, bus_addr_t min_addr,
+			 bus_addr_t max_addr, bus_dma_tag_t *newtag, int flags);
 /*
  * Common function for DMA map creation.  May be called by bus-specific
  * DMA map creation functions.
@@ -244,6 +246,13 @@
 	return (0);
 }
 
+int
+bus_dmatag_subregion(bus_dma_tag_t tag, bus_addr_t min_addr,
+		     bus_addr_t max_addr, bus_dma_tag_t *newtag, int flags)
+{
+	return (EOPNOTSUPP);
+}
+
 /*
  * Common function for loading a DMA map with a linear buffer.  May
  * be called by bus-specific DMA map load functions.
