[IA64] swiotlb abstraction (e.g. for Xen)

Add abstraction so that the file can be used by environments other than IA64
and EM64T, namely for Xen.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/include/asm-x86_64/swiotlb.h b/include/asm-x86_64/swiotlb.h
index f9c5895..ab913ff 100644
--- a/include/asm-x86_64/swiotlb.h
+++ b/include/asm-x86_64/swiotlb.h
@@ -44,6 +44,7 @@
 extern int swiotlb_force;
 
 #ifdef CONFIG_SWIOTLB
+#define SWIOTLB_ARCH_NEED_ALLOC
 extern int swiotlb;
 #else
 #define swiotlb 0