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diff --git a/include/VBox/vd-common.h b/include/VBox/vd-common.h
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+++ b/include/VBox/vd-common.h
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+/** @file
+ * VD: common definitions for the registration, backend and interface structures.
+ */
+
+/*
+ * Copyright (C) 2016-2019 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+#ifndef VBOX_INCLUDED_vd_common_h
+#define VBOX_INCLUDED_vd_common_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+#include <VBox/types.h>
+
+/** Makes a VD structure version out of an unique magic value and major &
+ * minor version numbers.
+ *
+ * @returns 32-bit structure version number.
+ *
+ * @param   uMagic      16-bit magic value.  This must be unique.
+ * @param   uMajor      12-bit major version number.  Structures with different
+ *                      major numbers are not compatible.
+ * @param   uMinor      4-bit minor version number.  When only the minor version
+ *                      differs, the structures will be 100% backwards
+ *                      compatible.
+ */
+#define VD_VERSION_MAKE(uMagic, uMajor, uMinor) \
+    ( ((uint32_t)(uMagic) << 16) | ((uint32_t)((uMajor) & 0xff) << 4) | ((uint32_t)((uMinor) & 0xf) << 0) )
+
+/** Checks if @a uVerMagic1 is compatible with @a uVerMagic2.
+ *
+ * @returns true / false.
+ * @param   uVerMagic1  Typically the runtime version of the struct.  This must
+ *                      have the same magic and major version as @a uVerMagic2
+ *                      and the minor version must be greater or equal to that
+ *                      of @a uVerMagic2.
+ * @param   uVerMagic2  Typically the version the code was compiled against.
+ *
+ * @remarks The parameters will be referenced more than once.
+ */
+#define VD_VERSION_ARE_COMPATIBLE(uVerMagic1, uVerMagic2) \
+    (    (uVerMagic1) == (uVerMagic2) \
+      || (   (uVerMagic1) >= (uVerMagic2) \
+          && ((uVerMagic1) & UINT32_C(0xfffffff0)) == ((uVerMagic2) & UINT32_C(0xfffffff0)) ) \
+    )
+
+#endif /* !VBOX_INCLUDED_vd_common_h */