1 files changed, 93 insertions, 0 deletions
diff --git a/src/VBox/VMM/Docs-CodingGuidelines.cpp b/src/VBox/VMM/Docs-CodingGuidelines.cpp
new file mode 100644
index 00000000..7894893d
--- /dev/null
+++ b/src/VBox/VMM/Docs-CodingGuidelines.cpp
@@ -0,0 +1,93 @@
+/* $Id: Docs-CodingGuidelines.cpp $ */
+/** @file
+ * VMM - Coding Guidelines.
+ */
+
+/*
+ * Copyright (C) 2006-2020 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.
+ */
+
+
+/** @page pg_vmm_guideline                  VMM Coding Guidelines
+ *
+ * The guidelines extends the VBox coding guidelines (@ref pg_vbox_guideline)
+ * and consists of a compulsory part and an optional part. It is very important
+ * that the rules of the compulsory part is followed. That will prevent obvious
+ * bugs, and it will ease porting the code to 32/64 and 64/32 bits setups.
+ *
+ *
+ *
+ * @section sec_vmm_guideline_compulsory        Compulsory
+ *
+ * It is of vital importance is to distinguish between addresses - both virtual
+ * and physical - applying to Guest Context and Host Context. To assist the
+ * coder in this, a set of types and macros have been created. Another vital
+ * thing is that structures shared between the two contexts ends up with the
+ * same size and member offsets in both places. There are types and macros
+ * for that too.
+ *
+ *
+ * The rules:
+ *
+ *      - When declaring pointers in shared structures use the RCPTRTYPE(),
+ *        R0PTRTYPE() and R3PTRTYPE() macros.
+ *
+ *      - Use RTGCPTR and RTHCPTR when dealing with the other context in
+ *        none shared structures, parameter lists, stack variables and such.
+ *
+ *      - Following the above rules, pointers will in a context other than the
+ *        one a pointer was defined for, appear as unsigned integers.
+ *
+ *      - It is NOT permitted to subject a pointer from the other context to pointer
+ *        types of the current context by direct cast or by definition.
+ *
+ *      - When doing pointer arithmetic cast using uintptr_t, intptr_t or char *.
+ *        Never cast a pointer to anything else for this purpose, that will not
+ *        work everywhere! (1)
+ *
+ *      - Physical addresses are also specific to their context. Use RTGCPHYS
+ *        and RTHCPHYS when dealing when them. Both types are unsigned integers.
+ *
+ *      - Integers in shared structures should be using a RT integer type or
+ *        any of the [u]int[0-9]+_t types. (2)
+ *
+ *      - If code is shared between the contexts, GCTYPE() can be used to declare
+ *        things differently. If GCTYPE() usage is extensive, don't share the code.
+ *
+ *      - The context is part of all public symbols which are specific to a single
+ *        context.
+ *
+ *
+ * (1) Talking about porting between 32-bit and 64-bit architectures and even
+ *     between 64-bit platforms. On 64-bit linux int is 32-bit, long is 64-bit.
+ *     However on 64-bit windows both int and long are 32-bit - there is no
+ *     standard 64 bit type (_int64 is not a standard type, it's an stupid
+ *     extension).
+ *
+ * (2) The VBox integer types are RTINT, RTUINT, RTGCINT, RTGCUINT,
+ *     RTGCINTPTR, RTGCUINTPTR, RTHCINT, RTHCUINT, RTHCINTPTR and
+ *     RTHCUINTPTR.
+ *
+ *
+ *
+ * @section sec_vmm_guideline_optional          Optional
+ *
+ * There are the general VBox guidelines, see @ref sec_vbox_guideline_optional.
+ * In addition to these for the following rules applies to the VMM:
+ *
+ *      - Prefixes GCPtr and HCPtr are preferred over suffixes HC and GC of
+ *        pointers.
+ *
+ *      - Prefixes GCPhys and HCPhys are generally used for physical addresses,
+ *        types RTGCPHYS and RTHCPHYS respectively.
+ *
+ */
+