diff --git a/arch/ia64/include/asm/xen/irq.h b/arch/ia64/include/asm/xen/irq.h
new file mode 100644
index 0000000000000000000000000000000000000000..a9045098300318087dea8713463879e388003842
--- /dev/null
+++ b/arch/ia64/include/asm/xen/irq.h
@@ -0,0 +1,44 @@
+/******************************************************************************
+ * arch/ia64/include/asm/xen/irq.h
+ *
+ * Copyright (c) 2008 Isaku Yamahata <yamahata at valinux co jp>
+ *                    VA Linux Systems Japan K.K.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ */
+
+#ifndef _ASM_IA64_XEN_IRQ_H
+#define _ASM_IA64_XEN_IRQ_H
+
+/*
+ * The flat IRQ space is divided into two regions:
+ *  1. A one-to-one mapping of real physical IRQs. This space is only used
+ *     if we have physical device-access privilege. This region is at the
+ *     start of the IRQ space so that existing device drivers do not need
+ *     to be modified to translate physical IRQ numbers into our IRQ space.
+ *  3. A dynamic mapping of inter-domain and Xen-sourced virtual IRQs. These
+ *     are bound using the provided bind/unbind functions.
+ */
+
+#define XEN_PIRQ_BASE		0
+#define XEN_NR_PIRQS		256
+
+#define XEN_DYNIRQ_BASE		(XEN_PIRQ_BASE + XEN_NR_PIRQS)
+#define XEN_NR_DYNIRQS		(NR_CPUS * 8)
+
+#define XEN_NR_IRQS		(XEN_NR_PIRQS + XEN_NR_DYNIRQS)
+
+#endif /* _ASM_IA64_XEN_IRQ_H */
diff --git a/arch/ia64/kernel/nr-irqs.c b/arch/ia64/kernel/nr-irqs.c
index 8273afc32db8cf342a526e2c75c70cf3b3995e78..ee564575148ed54da0b03cfdddae484acbcb9b1a 100644
--- a/arch/ia64/kernel/nr-irqs.c
+++ b/arch/ia64/kernel/nr-irqs.c
@@ -10,6 +10,7 @@
 #include <linux/kbuild.h>
 #include <linux/threads.h>
 #include <asm/native/irq.h>
+#include <asm/xen/irq.h>
 
 void foo(void)
 {