diff --git a/sys/dev/pci/pci_iov.c b/sys/dev/pci/pci_iov.c
--- a/sys/dev/pci/pci_iov.c
+++ b/sys/dev/pci/pci_iov.c
@@ -736,6 +736,7 @@
 
 	/* We don't yet support allocating extra bus numbers for VFs. */
 	if (pci_get_bus(dev) != PCI_RID2BUS(last_rid)) {
+		device_printf(dev, "not enough PCIe bus numbers for VFs\n");
 		error = ENOSPC;
 		goto out;
 	}