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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
28 source directory irregardless of the destination directory. This means
29 #include "" and #include <> work as expected and more importantly
30 running 'make' in the source directory will work as expected. The
31 environment variable or make parameter 'BUILD' sets the build directory.
32 It may be an absolute path or a path relative to the top level directory.
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
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
39 one failure condition that occures when a header file is erased. In
40 this case you should run make clean to purge the .o and .d files to
41 rebuild.
42
43 The final significant deviation from normal make practicies is
44 in how the build directory is managed. It is not mearly a mirror of
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/
52 obj/
53 apt-pkg/
54 cmndline/
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
59 all runnable programs are within the bin/ directory, a huge benifit for
60 debugging inter-program relationships. The .so files are also placed in
61 bin/ for simplicity.
62
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
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
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
90 aclocal -I buidlib
91 autoconf
92 [Altertatively you can run make startup in the top level build dir]
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
106 Autoconf will also wite a makefile into the top level of the build dir,
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
112 source directory and exporting BUILD.