diff --git a/docs/designs/dmop.pandoc b/docs/designs/dmop.pandoc
index 8e9f95af47..49e52b1bcc 100644
--- a/docs/designs/dmop.pandoc
+++ b/docs/designs/dmop.pandoc
@@ -4,9 +4,15 @@ DMOP
 Introduction
 ------------
 
-The aim of DMOP is to prevent a compromised device model from compromising
-domains other than the one it is providing emulation for (which is therefore
-likely already compromised).
+The DMOP hypercall has a new ABI design to solve problems in the Xen
+ecosystem.  First, the ABI is fully stable, to reduce the coupling between
+device models and the version of Xen.  Specifically, device model software
+using DMOP (be it user, stub domain or kernel software) need not be recompiled
+to match the version of the running hypervisor.
+
+Secondly, for device models in userspace, the ABI is designed specifically to
+allow a kernel to audit the memory ranges used, without having to know the
+internal structure of sub-ops.
 
 The problem occurs when you a device model issues an hypercall that
 includes references to user memory other than the operation structure
diff --git a/tools/libs/devicemodel/private.h b/tools/libs/devicemodel/private.h
index c4a225f8af..c24f3396bb 100644
--- a/tools/libs/devicemodel/private.h
+++ b/tools/libs/devicemodel/private.h
@@ -1,8 +1,6 @@
 #ifndef XENDEVICEMODEL_PRIVATE_H
 #define XENDEVICEMODEL_PRIVATE_H
 
-#define __XEN_TOOLS__ 1
-
 #include <xentoollog.h>
 #include <xendevicemodel.h>
 #include <xencall.h>
diff --git a/xen/include/public/hvm/dm_op.h b/xen/include/public/hvm/dm_op.h
index ef7fbc0d3d..fa3f083fed 100644
--- a/xen/include/public/hvm/dm_op.h
+++ b/xen/include/public/hvm/dm_op.h
@@ -25,9 +25,6 @@
 #define __XEN_PUBLIC_HVM_DM_OP_H__
 
 #include "../xen.h"
-
-#if defined(__XEN__) || defined(__XEN_TOOLS__)
-
 #include "../event_channel.h"
 
 #ifndef uint64_aligned_t
@@ -491,8 +488,6 @@ struct xen_dm_op {
     } u;
 };
 
-#endif /* __XEN__ || __XEN_TOOLS__ */
-
 struct xen_dm_op_buf {
     XEN_GUEST_HANDLE(void) h;
     xen_ulong_t size;