| 1 | /* $Id: VBox-MakefileGuidelines.cpp 69500 2017-10-28 15:14:05Z 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) 2009-2017 Oracle Corporation
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| 8 | *
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| 9 | * This file is part of VirtualBox Open Source Edition (OSE), as
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| 10 | * available from http://www.virtualbox.org. This file is free software;
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| 11 | * you can redistribute it and/or modify it under the terms of the GNU
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| 12 | * General Public License (GPL) as published by the Free Software
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| 13 | * Foundation, in version 2 as it comes in the "COPYING" file of the
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| 14 | * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
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| 15 | * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
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| 16 | */
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| 17 |
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| 18 | /** @page pg_vbox_makefile_guidelines VBox Makefile Guidelines
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| 19 | *
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| 20 | * These guidelines apply to all the Makefile.kmk files in the tree.
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| 21 | * No exceptions.
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| 22 | *
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| 23 | * All these makefiles are ultimately the responsiblity of bird. Since there are
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| 24 | * currently more than two hundred files and the number is growing, they have to
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| 25 | * be very kept uniform or it will become very difficult to maintain them and
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| 26 | * impossible do bulk refactoring. Thus these guidelines have no bits that are
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| 27 | * optional unlike the coding guidelines, and should be thought of as rules
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| 28 | * rather than guidelines.
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| 29 | *
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| 30 | * Note! The guidelines do not apply to the other makefiles found in the source
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| 31 | * tree, like the ones shipped in the SDK and the ones for the linux kernel
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| 32 | * modules.
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| 33 | *
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| 34 | *
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| 35 | * @section sec_vbox_makefile_guidelines_kbuild kBuild
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| 36 | *
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| 37 | * kBuild is way older than VirtualBox, at least as a concept, but the
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| 38 | * VirtualBox project was a push to get something done about it again. It's
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| 39 | * maintained by bird in his spare time because: "We don't make buildsystems, we
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| 40 | * make virtual machines". So, kBuild makes progress when there is spare time or
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| 41 | * when there is an urgent need for something.
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| 42 | *
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| 43 | * The kBuild docs are in the process of being written. The current items and
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| 44 | * their status per 2009-04-19:
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| 45 | * - kmk Quick Reference [completed]:
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| 46 | * http://svn.netlabs.org/kbuild/wiki/kmk%20Quick%20Reference
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| 47 | * - kBuild Quick Reference [just started]:
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| 48 | * http://svn.netlabs.org/kbuild/wiki/kBuild%20Quick%20Reference
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| 49 | *
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| 50 | * Local copies of the docs can be found in kBuild/docs, just keep in mind that
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| 51 | * they might be slightly behind the online version.
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| 52 | *
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| 53 | *
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| 54 | * @section sec_vbox_makefile_guidelines_example Example Makefiles
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| 55 | *
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| 56 | * Let me point to some good sample makefiles:
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| 57 | * - src/VBox/Additions/common/VBoxService/Makefile.kmk
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| 58 | * - src/VBox/Debugger/Makefile.kmk
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| 59 | * - src/VBox/Disassembler/Makefile.kmk
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| 60 | *
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| 61 | * And some bad ones:
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| 62 | * - src/lib/xpcom18a4/Makefile.kmk
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| 63 | * - src/recompiler/Makefile.kmk
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| 64 | * - src/VBox/Devices/Makefile.kmk
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| 65 | * - src/VBox/Main/Makefile.kmk
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| 66 | * - src/VBox/Runtime/Makefile.kmk
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| 67 | *
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| 68 | *
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| 69 | * @section sec_vbox_makefile_guidelines Guidelines
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| 70 | *
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| 71 | * First one really important fact:
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| 72 | *
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| 73 | * Everything is global because all makefiles
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| 74 | * are virtually one single makefile.
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| 75 | *
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| 76 | * The rules:
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| 77 | *
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| 78 | * - Using bits defined by a sub-makefile is fine, using anything defined
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| 79 | * by a parent, sibling, uncle, cousine, or remoter relatives is not
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| 80 | * Okay. It may break sub-tree building which is not acceptable.
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| 81 | *
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| 82 | * - Template names starts with VBOX and are all upper cased, no
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| 83 | * underscores or other separators. (TODO: Change this to camel case.)
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| 84 | *
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| 85 | * - Makefile variables shall be prefixed with VBOX or VB to avoid clashes
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| 86 | * with environment and kBuild variables.
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| 87 | *
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| 88 | * - Makefile variables are all upper cased and uses underscores to
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| 89 | * separate the words.
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| 90 | *
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| 91 | * - All variables are global. Make sure they are globally unique, but try
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| 92 | * not make them incredible long.
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| 93 | *
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| 94 | * - Makefile variables goes after the inclusion of the header and
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| 95 | * usually after including sub-makefiles.
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| 96 | *
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| 97 | * - Variables that are used by more than one makefile usually belongs
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| 98 | * in the monster file, Config.kmk.
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| 99 | *
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| 100 | * - Targets are lower or camel cased and as a rule the same as the
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| 101 | * resulting binary.
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| 102 | *
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| 103 | * - Install targets frequently have a -inst in their name, and a name that
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| 104 | * gives some idea what they install
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| 105 | *
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| 106 | * - Always use templates (mytarget_TEMPLATE = VBOXSOMETHING).
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| 107 | *
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| 108 | * - Comment each target with a 3+ line block as seen in
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| 109 | * src/VBox/Debugger/Makefile.kmk.
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| 110 | *
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| 111 | * - No space between the comment block and the target definition.
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| 112 | *
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| 113 | * - Try fit all the custom recipes after the target they apply to.
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| 114 | *
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| 115 | * - Custom recipes that apply to more than one target should be placed at
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| 116 | * the bottom of the makefile, before the footer inclusion when possible.
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| 117 | *
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| 118 | * - Do NOT use custom recipes to install stuff, use install targets.
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| 119 | * Generate files to inst-target_0_OUTDIR. (Yes, there are a lot places
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| 120 | * where we don't do this yet.)
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| 121 | *
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| 122 | * - Always break SOURCES, LIBS, long target list and other lists the
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| 123 | * manner Debugger_SOURCES is broken into multiple lines in
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| 124 | * src/VBox/Debugger/Makefile.kmk. I.e. exactly one tab, the file name /
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| 125 | * list item, another space, the slash and then the newline.
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| 126 | *
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| 127 | * - The last element of an broken list should not have a slash-newline,
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| 128 | * otherwise we risk getting the next variable into the list.
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| 129 | *
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| 130 | * - Indentation of if'ed blocks is done in 1 space increments, this also
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| 131 | * applies to broken lists. It does not apply to the commands in a
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| 132 | * recipes of course, because that would make kmk choke. (Yes, there are
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| 133 | * plenty examples of doing this differently, but these will be weeded
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| 134 | * out over time.)
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| 135 | *
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| 136 | * - \$(NO_SUCH_VARIABLE) should be when you need to put nothing somewhere,
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| 137 | * for instance to prevent inherting an attribute.
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| 138 | *
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| 139 | * - Always put the defines in the DEFS properties, never use the FLAGS
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| 140 | * properties for this. Doing so may screw up depenencies and object
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| 141 | * caches.
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| 142 | *
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| 143 | * - Mark each section and target of the file with a 3+ lines comment
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| 144 | * block.
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| 145 | *
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| 146 | * - Document variables that are not obvious using double hash comments.
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| 147 | *
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| 148 | * - Each an every Makefile.kmk shall have a file header with Id, file
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| 149 | * description and copyright/license exactly like in the examples.
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| 150 | *
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| 151 | * - Multiple blank lines in a makefile is very seldom there without a
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| 152 | * reason and shall be preserved.
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| 153 | *
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| 154 | * - Inserting blank lines between target properties is all right if the
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| 155 | * target definition is long and/or crooked.
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| 156 | *
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| 157 | * - if1of and ifn1of shall always have a space after the comma, while ifeq
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| 158 | * and ifneq shall not. That way they are easier to tell apart.
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| 159 | *
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| 160 | * - Do a svn diff before committing makefile changes.
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| 161 | *
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| 162 | *
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| 163 | * @section sec_vbox_makefile_guidelines_reminders Helpful reminders
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| 164 | *
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| 165 | * - Do not be afraid to ask for help on IRC or in the defect you're
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| 166 | * working on. There are usually somebody around that know how to best do
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| 167 | * something.
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| 168 | *
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| 169 | * - Watch out for "Heads Up!" bugtracker messages concerning the build
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| 170 | * system.
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| 171 | *
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| 172 | * - To remove bits from a template you're using you have to create a new
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| 173 | * template that extends the existing one and creatively use
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| 174 | * \$(filter-out) or \$(patsubst).
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| 175 | *
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| 176 | * - You can build sub-trees.
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| 177 | *
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| 178 | * - You don't have to cd into sub-trees: kmk -C src/recompiler
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| 179 | *
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| 180 | * - You can build individual targets: kmk VBoxRT
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| 181 | *
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| 182 | * - Even install targets: kmk nobin
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| 183 | *
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| 184 | * - You can compile individual source files: kmk ConsoleImpl.o
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| 185 | *
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| 186 | */
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| 187 |
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