diff --git a/[refs] b/[refs]
index 79c9ecf92645..29d78544f88f 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: b15993fcc1bf15f717fb4414b32e4a11534dfdc4
+refs/heads/master: 3e334239d89d4a71610be5a3e8432464d421d9ec
diff --git a/trunk/drivers/block/xen-blkfront.c b/trunk/drivers/block/xen-blkfront.c
index 9c6f3f99208d..2e7c81e3f36a 100644
--- a/trunk/drivers/block/xen-blkfront.c
+++ b/trunk/drivers/block/xen-blkfront.c
@@ -47,6 +47,7 @@
 
 #include <xen/interface/grant_table.h>
 #include <xen/interface/io/blkif.h>
+#include <xen/interface/io/protocols.h>
 
 #include <asm/xen/hypervisor.h>
 
@@ -614,6 +615,12 @@ static int talk_to_backend(struct xenbus_device *dev,
 		message = "writing event-channel";
 		goto abort_transaction;
 	}
+	err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
+			    XEN_IO_PROTO_ABI_NATIVE);
+	if (err) {
+		message = "writing protocol";
+		goto abort_transaction;
+	}
 
 	err = xenbus_transaction_end(xbt, 0);
 	if (err) {
diff --git a/trunk/include/xen/interface/io/protocols.h b/trunk/include/xen/interface/io/protocols.h
new file mode 100644
index 000000000000..01fc8ae5f0b0
--- /dev/null
+++ b/trunk/include/xen/interface/io/protocols.h
@@ -0,0 +1,21 @@
+#ifndef __XEN_PROTOCOLS_H__
+#define __XEN_PROTOCOLS_H__
+
+#define XEN_IO_PROTO_ABI_X86_32     "x86_32-abi"
+#define XEN_IO_PROTO_ABI_X86_64     "x86_64-abi"
+#define XEN_IO_PROTO_ABI_IA64       "ia64-abi"
+#define XEN_IO_PROTO_ABI_POWERPC64  "powerpc64-abi"
+
+#if defined(__i386__)
+# define XEN_IO_PROTO_ABI_NATIVE XEN_IO_PROTO_ABI_X86_32
+#elif defined(__x86_64__)
+# define XEN_IO_PROTO_ABI_NATIVE XEN_IO_PROTO_ABI_X86_64
+#elif defined(__ia64__)
+# define XEN_IO_PROTO_ABI_NATIVE XEN_IO_PROTO_ABI_IA64
+#elif defined(__powerpc64__)
+# define XEN_IO_PROTO_ABI_NATIVE XEN_IO_PROTO_ABI_POWERPC64
+#else
+# error arch fixup needed here
+#endif
+
+#endif