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1 | The Make System |
2 | ~~~ ~~~~ ~~~~~~ | |
3 | To compile this program you require GNU Make. In fact you probably need | |
4 | GNU Make 3.76.1 or newer. The makefiles contained make use of many | |
5 | GNU Make specific features and will not run on other makes. | |
6 | ||
7 | The make system has a number of interesting properties that are not found | |
8 | in other systems such as automake or the GNU makefile standards. In | |
9 | general some semblance of expectedness is kept so as not to be too | |
10 | surprising. Basically the following will work as expected: | |
11 | ||
12 | ./configure | |
13 | make | |
14 | or | |
15 | cd build | |
16 | ../configure | |
17 | make | |
18 | ||
19 | There are a number of other things that are possible that may make software | |
20 | development and software packaging simpler. The first of these is the | |
21 | environment.mak file. When configure is run it creates an environment.mak | |
22 | file in the build directory. This contains -all- configurable parameters | |
23 | for all of the make files in all of the subdirectories. Changing one | |
24 | of these parameters will have an immediate effect. The use of makefile.in | |
25 | and configure substitutions across build makefiles is not used at all. | |
26 | ||
27 | Furthermore, the make system runs with a current directory equal to the | |
1e3f4083 | 28 | source directory regardless of the destination directory. This means |
4ae405e9 | 29 | #include "" and #include <> work as expected and more importantly |
93641593 | 30 | running 'make' in the source directory will work as expected. The |
4ae405e9 | 31 | environment variable or make parameter 'BUILD' sets the build directory. |
93641593 | 32 | It may be an absolute path or a path relative to the top level directory. |
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33 | By default build-arch/ then build/ will be used with a fall back to ./ This |
34 | means you can get all the advantages of a build directory without having to | |
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35 | cd into it to edit your source code! |
36 | ||
37 | The make system also performs dependency generation on the fly as the | |
38 | compiler runs. This is extremely fast and accurate. There is however | |
7365ff46 | 39 | one failure condition that occurs when a header file is erased. In |
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40 | this case you should run make clean to purge the .o and .d files to |
41 | rebuild. | |
42 | ||
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43 | The final significant deviation from normal make practices is |
44 | in how the build directory is managed. It is not nearly a mirror of | |
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45 | the source directory but is logically divided in the following manner |
46 | bin/ | |
47 | methods/ | |
48 | doc/ | |
49 | examples/ | |
50 | include/ | |
51 | apt-pkg/ | |
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52 | obj/ |
53 | apt-pkg/ | |
7365ff46 | 54 | cmdline/ |
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55 | [...] |
56 | Only .o and .d files are placed in the obj/ subdirectory. The final compiled | |
57 | binaries are placed in bin, published headers for inter-component linking | |
58 | are placed in include/ and documentation is generated into doc/. This means | |
7365ff46 | 59 | all runnable programs are within the bin/ directory, a huge benefit for |
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60 | debugging inter-program relationships. The .so files are also placed in |
61 | bin/ for simplicity. | |
62 | ||
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63 | By default make is put into silent mode. During operation there should be |
64 | no shell or compiler messages only status messages from the makefiles, | |
65 | if any pop up that indicates there may be a problem with your environment. | |
66 | For debugging you can disable this by setting NOISY=1, ala | |
67 | make NOISY=1 | |
68 | ||
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69 | Using the makefiles |
70 | ~~~~~ ~~~ ~~~~~~~~~ | |
71 | The makefiles for the components are really simple. The complexity is hidden | |
72 | within the buildlib/ directory. Each makefile defines a set of make variables | |
73 | for the bit it is going to make then includes a makefile fragment from | |
74 | the buildlib/. This fragment generates the necessary rules based on the | |
75 | originally defined variables. This process can be repeated as many times as | |
76 | necessary for as many programs or libraries as are in the directory. | |
77 | ||
78 | Many of the make fragments have some useful properties involving sub | |
79 | directories and other interesting features. They are more completely | |
80 | described in the fragment code in buildlib. Some tips on writing fragments | |
81 | are included in buildlib/defaults.mak | |
82 | ||
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83 | The fragments are NEVER processed by configure, so if you make changes to |
84 | them they will have an immediate effect. | |
85 | ||
86 | Autoconf | |
87 | ~~~~~~~~ | |
88 | Straight out of CVS you have to initialize autoconf. This requires | |
89 | automake (I really don't know why) and autoconf and requires doing | |
7365ff46 | 90 | aclocal -I buildlib |
93bf083d | 91 | autoconf |
7365ff46 | 92 | [Alternatively you can run make startup in the top level build dir] |
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93 | |
94 | Autoconf is configured to do some basic system probes for optional and | |
95 | required functionality and generate an environment.mak and include/config.h | |
96 | from it's findings. It will then write a 'makefile' and run make dirs to | |
97 | create the output directory tree. | |
98 | ||
99 | It is not my belief that autoconf should be used to generate substantial | |
100 | source code markup to escape OS problems. If an OS problem does crop up | |
101 | it can likely be corrected by installing the correct files into the | |
102 | build include/ dir and perhaps writing some replacement code and | |
103 | linking it in. To the fullest extent possible the source code should conform | |
104 | to standards and not cater to broken systems. | |
105 | ||
7365ff46 | 106 | Autoconf will also write a makefile into the top level of the build dir, |
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107 | this simply acts as a wrapper to the main top level make in the source tree. |
108 | There is one big warning, you can't use both this make file and the | |
109 | ones in the top level tree. Make is not able to resolve rules that | |
110 | go to the same file through different paths and this will confuse the | |
111 | depends mechanism. I recommend always using the makefiles in the | |
92c26a2f | 112 | source directory and exporting BUILD. |