| 1 | /* $Id: VBox-MakefileGuidelines.cpp 98103 2023-01-17 14:15:46Z vboxsync $ */
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| 2 | /** @file
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| 3 | * VBox - Makefile Guidelines.
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| 4 | */
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| 5 |
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| 6 | /*
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| 7 | * Copyright (C) 2009-2023 Oracle and/or its affiliates.
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| 8 | *
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| 9 | * This file is part of VirtualBox base platform packages, as
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| 10 | * available from https://www.virtualbox.org.
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| 11 | *
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| 12 | * This program is free software; you can redistribute it and/or
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| 13 | * modify it under the terms of the GNU General Public License
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| 14 | * as published by the Free Software Foundation, in version 3 of the
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| 15 | * License.
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| 16 | *
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| 17 | * This program is distributed in the hope that it will be useful, but
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| 18 | * WITHOUT ANY WARRANTY; without even the implied warranty of
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| 19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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| 20 | * General Public License for more details.
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| 21 | *
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| 22 | * You should have received a copy of the GNU General Public License
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| 23 | * along with this program; if not, see <https://www.gnu.org/licenses>.
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| 24 | *
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| 25 | * SPDX-License-Identifier: GPL-3.0-only
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| 26 | */
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| 27 |
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| 28 | /** @page pg_vbox_makefile_guidelines VBox Makefile Guidelines
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| 29 | *
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| 30 | * These guidelines apply to all the Makefile.kmk files in the tree.
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| 31 | * No exceptions.
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| 32 | *
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| 33 | * All these makefiles are ultimately the responsiblity of bird. Since there
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| 34 | * are currently more than three hundred files and the number is growing, they
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| 35 | * have to be very kept uniform or it will become very difficult to maintain
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| 36 | * them and impossible do bulk refactoring. Thus these guidelines have no bits
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| 37 | * that are optional unlike the coding guidelines, and should be thought of as
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| 38 | * rules rather than guidelines.
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| 39 | *
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| 40 | * Note! The guidelines do not apply to the non-kBuild makefiles found in the
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| 41 | * source tree, like the ones shipped in the SDK and the ones for the
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| 42 | * linux kernel modules.
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| 43 | *
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| 44 | *
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| 45 | * @section sec_vbox_makefile_guidelines_kbuild kBuild
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| 46 | *
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| 47 | * kBuild is way older than VirtualBox, at least as a concept, but the
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| 48 | * VirtualBox project was a push to get something done about it again. It's
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| 49 | * maintained by bird in his spare time because: "We don't make buildsystems, we
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| 50 | * make virtual machines". So, kBuild makes progress when there is spare time
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| 51 | * or when there is an urgent need for something.
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| 52 | *
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| 53 | * The kBuild docs are in the process of being written. The current items and
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| 54 | * their status per 2018-10-29:
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| 55 | * - kmk Quick Reference [completed]:
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| 56 | * http://svn.netlabs.org/kbuild/wiki/kmk%20Quick%20Reference
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| 57 | * - kBuild Quick Reference [just started]:
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| 58 | * http://svn.netlabs.org/kbuild/wiki/kBuild%20Quick%20Reference
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| 59 | *
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| 60 | * Local copies of the docs can be found in kBuild/docs, just keep in mind that
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| 61 | * they might be slightly behind the online version.
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| 62 | *
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| 63 | *
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| 64 | * @section sec_vbox_makefile_guidelines_example Example Makefiles
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| 65 | *
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| 66 | * Let me point to some good sample makefiles:
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| 67 | * - src/VBox/Additions/common/VBoxService/Makefile.kmk
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| 68 | * - src/VBox/Debugger/Makefile.kmk
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| 69 | * - src/VBox/Disassembler/Makefile.kmk
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| 70 | *
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| 71 | * And some bad ones:
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| 72 | * - src/lib/xpcom18a4/Makefile.kmk
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| 73 | * - src/recompiler/Makefile.kmk
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| 74 | * - src/VBox/Devices/Makefile.kmk
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| 75 | * - src/VBox/Main/Makefile.kmk
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| 76 | * - src/VBox/Runtime/Makefile.kmk
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| 77 | *
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| 78 | *
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| 79 | * @section sec_vbox_makefile_guidelines Guidelines
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| 80 | *
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| 81 | * First one really important fact:
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| 82 | *
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| 83 | * Everything is global because all makefiles
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| 84 | * are virtually one single makefile.
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| 85 | *
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| 86 | * The rules:
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| 87 | *
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| 88 | * - Using bits defined by a sub-makefile is fine, using anything defined
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| 89 | * by a parent, sibling, uncle, cousine, or remoter relatives is not
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| 90 | * Okay. It may break sub-tree building which is not acceptable.
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| 91 | *
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| 92 | * - Template names starts with VBox and are camel cased, no
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| 93 | * underscores or other separators. (Note this used to be all upper
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| 94 | * case, fixing this incomplete.)
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| 95 | *
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| 96 | * - Makefile variables shall be prefixed with VBOX or VB to avoid clashes
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| 97 | * with environment and kBuild variables.
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| 98 | *
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| 99 | * - Makefile variables are all upper cased and uses underscores to
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| 100 | * separate the words.
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| 101 | *
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| 102 | * - All variables are global. Make sure they are globally unique, but try
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| 103 | * not make them incredible long.
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| 104 | *
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| 105 | * - Makefile variables goes after the inclusion of the header and
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| 106 | * usually after including sub-makefiles.
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| 107 | *
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| 108 | * - Variables that are used by more than one makefile usually ends up
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| 109 | * in the monster file, Config.kmk. However, see if there are any
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| 110 | * sub-tree specific Config.kmk files that could do the job first.
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| 111 | *
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| 112 | * - Targets are lower or camel cased and as a rule the same as the
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| 113 | * resulting binary.
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| 114 | *
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| 115 | * - Install targets frequently have a -inst in their name, and a name that
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| 116 | * gives some idea what they install
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| 117 | *
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| 118 | * - Always use templates (mytarget_TEMPLATE = VBoxSomething).
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| 119 | *
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| 120 | * - Comment each target with a 3+ line block as seen in
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| 121 | * src/VBox/Debugger/Makefile.kmk.
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| 122 | *
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| 123 | * - No space between the comment block and the target definition.
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| 124 | *
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| 125 | * - Try fit all the custom recipes after the target they apply to.
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| 126 | *
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| 127 | * - Custom recipes that apply to more than one target should be placed at
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| 128 | * the bottom of the makefile, before the footer inclusion when possible.
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| 129 | *
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| 130 | * - Do NOT use custom recipes to install stuff, use install targets.
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| 131 | * Generate files to inst-target_0_OUTDIR. (Yes, there are a lot places
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| 132 | * where we don't do this yet.)
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| 133 | *
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| 134 | * - Always break SOURCES, LIBS, long target list and other lists the
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| 135 | * manner Debugger_SOURCES is broken into multiple lines in
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| 136 | * src/VBox/Debugger/Makefile.kmk. I.e. exactly one tab, the file name /
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| 137 | * list item, another space, the slash and then the newline.
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| 138 | *
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| 139 | * - Line continuation slashes shall never ever be aligned vertically (that
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| 140 | * always goes crooked sooner or later), but have exactly one space
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| 141 | * before them.
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| 142 | *
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| 143 | * - The last element of an broken list shall not have a slash-newline,
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| 144 | * otherwise we risk getting the next variable into the list.
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| 145 | *
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| 146 | * - When if'ed blocks come into play, we will only indent the conditional
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| 147 | * makefile directives (if, ifeq, ifneq, if1of, ifn1of, ifdef, ifndef,
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| 148 | * else, endif, ++), one space for each level. (Note! We used to indent
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| 149 | * non-directives, which made emacs upset as we'd have both tabs and
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| 150 | * spaces on as indentation on the same line. There are a lot of cases
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| 151 | * of this still around.)
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| 152 | *
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| 153 | * - \$(NO_SUCH_VARIABLE) should be when you need to put nothing somewhere,
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| 154 | * for instance to prevent inherting an attribute.
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| 155 | *
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| 156 | * - Always put the defines in the DEFS properties, never use the FLAGS
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| 157 | * properties for this. Doing so may screw up depenencies and object
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| 158 | * caches.
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| 159 | *
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| 160 | * - Mark each section and target of the file with a 3+ lines comment
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| 161 | * block.
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| 162 | *
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| 163 | * - Document variables that are not immediately obvious using double hash
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| 164 | * comments, doxygen style.
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| 165 | *
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| 166 | * - Each an every Makefile.kmk shall have a file header with Id, file
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| 167 | * description and copyright/license exactly like in the examples. (The
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| 168 | * SCM tool will complain if you don't.)
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| 169 | *
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| 170 | * - Multiple blank lines in a makefile is very seldom there without a
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| 171 | * reason and shall be preserved.
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| 172 | *
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| 173 | * - Inserting blank lines between target properties is all right if the
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| 174 | * target definition is long and/or crooked.
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| 175 | *
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| 176 | * - if1of and ifn1of shall always have a space after the comma, while ifeq
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| 177 | * and ifneq shall not. That way they are easier to tell apart.
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| 178 | *
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| 179 | * - Do a svn diff before committing makefile changes.
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| 180 | *
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| 181 | *
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| 182 | * @section sec_vbox_makefile_guidelines_reminders Helpful reminders
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| 183 | *
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| 184 | * - Do not be afraid to ask for help on IRC or in the defect you're
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| 185 | * working on. There are usually somebody around that know how to best do
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| 186 | * something.
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| 187 | *
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| 188 | * - Watch out for "Heads Up!" bugtracker messages concerning the build
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| 189 | * system.
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| 190 | *
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| 191 | * - To remove bits from a template you're using you have to create a new
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| 192 | * template that extends the existing one and creatively use
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| 193 | * \$(filter-out) or \$(patsubst).
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| 194 | *
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| 195 | * - You can build sub-trees.
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| 196 | *
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| 197 | * - You don't have to cd into sub-trees: kmk -C src/recompiler
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| 198 | *
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| 199 | * - You can build individual targets: kmk VBoxRT
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| 200 | *
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| 201 | * - Even install targets: kmk nobin
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| 202 | *
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| 203 | * - You can compile individual source files: kmk ConsoleImpl.o
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| 204 | *
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| 205 | * - You can tell kmk to continue on failure: kmk -k
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| 206 | *
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| 207 | * - You can tell kmk to run at low priority: kmk --nice
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| 208 | *
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| 209 | * - The --pretty-command-printing option is useful for seeing exactly
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| 210 | * what's passed to the tools.
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| 211 | *
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| 212 | * - You can invoke recipes in the root makefile more efficiently via the
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| 213 | * Maintenance.kmk file: kmk -f Maintenance.kmk incs
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| 214 | *
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| 215 | */
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| 216 |
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