diff --git a/include/xen/interface/xen.h b/include/xen/interface/xen.h
index eec8ab75b9..a7c8ed781b 100644
--- a/include/xen/interface/xen.h
+++ b/include/xen/interface/xen.h
@@ -76,6 +76,12 @@
 #define __HYPERVISOR_arch_6               54
 #define __HYPERVISOR_arch_7               55
 
+/*
+ * Commands to HYPERVISOR_console_io().
+ */
+#define CONSOLEIO_write         0
+#define CONSOLEIO_read          1
+
 #ifndef __ASSEMBLY__
 
 typedef u16 domid_t;