Index: head/sys/amd64/include/iommu.h
===================================================================
--- head/sys/amd64/include/iommu.h
+++ head/sys/amd64/include/iommu.h
@@ -0,0 +1,6 @@
+/*-
+ * This file is in the public domain.
+ */
+/* $FreeBSD$ */
+
+#include <x86/iommu.h>
Index: head/sys/dev/iommu/busdma_iommu.c
===================================================================
--- head/sys/dev/iommu/busdma_iommu.c
+++ head/sys/dev/iommu/busdma_iommu.c
@@ -59,17 +59,12 @@
 #include <vm/vm_object.h>
 #include <vm/vm_page.h>
 #include <vm/vm_map.h>
+#include <dev/iommu/iommu.h>
 #include <machine/atomic.h>
 #include <machine/bus.h>
 #include <machine/md_var.h>
-#if defined(__amd64__) || defined(__i386__)
-#include <machine/specialreg.h>
-#include <x86/include/busdma_impl.h>
-#include <x86/iommu/intel_reg.h>
+#include <machine/iommu.h>
 #include <dev/iommu/busdma_iommu.h>
-#include <dev/iommu/iommu.h>
-#include <x86/iommu/intel_dmar.h>
-#endif
 
 /*
  * busdma_iommu.c, the implementation of the busdma(9) interface using
Index: head/sys/dev/iommu/iommu_gas.c
===================================================================
--- head/sys/dev/iommu/iommu_gas.c
+++ head/sys/dev/iommu/iommu_gas.c
@@ -65,9 +65,7 @@
 #include <machine/atomic.h>
 #include <machine/bus.h>
 #include <machine/md_var.h>
-#if defined(__amd64__) || defined(__i386__)
-#include <x86/iommu/intel_reg.h>
-#endif
+#include <machine/iommu.h>
 #include <dev/iommu/busdma_iommu.h>
 
 /*
Index: head/sys/i386/include/iommu.h
===================================================================
--- head/sys/i386/include/iommu.h
+++ head/sys/i386/include/iommu.h
@@ -0,0 +1,6 @@
+/*-
+ * This file is in the public domain.
+ */
+/* $FreeBSD$ */
+
+#include <x86/iommu.h>
Index: head/sys/x86/include/iommu.h
===================================================================
--- head/sys/x86/include/iommu.h
+++ head/sys/x86/include/iommu.h
@@ -0,0 +1,13 @@
+/*-
+ * This file is in the public domain.
+ */
+/* $FreeBSD$ */
+
+#ifndef	_MACHINE_IOMMU_H_
+#define	_MACHINE_IOMMU_H_
+
+#include <x86/include/busdma_impl.h>
+#include <x86/iommu/intel_reg.h>
+#include <x86/iommu/intel_dmar.h>
+
+#endif /* !_MACHINE_IOMMU_H_ */