1 Build Framework
2 ===============
3
4 The perf build framework was adopted from the
5 idea and the way how objects are built is the
6
7 Basically the user provides set of 'Build' fil
8 directories to nest for specific target to be
9
10 Unlike the kernel we don't have a single build
11 we setup source objects, but we support more.
12 carry a sources list for multiple build object
13
14
15 Build framework makefiles
16 -------------------------
17
18 The build framework consists of 2 Makefiles:
19
20 Build.include
21 Makefile.build
22
23 While the 'Build.include' file contains just s
24 'Makefile.build' file is the makefile used fro
25 interface/usage is following:
26
27 $ make -f tools/build/Makefile.build srctree
28
29 where:
30
31 KSRC - is the path to kernel sources
32 DIR - is the path to the project to be bu
33 OBJECT - is the name of the build object
34
35 When succefully finished the $(DIR) directory
36 called $(OBJECT)-in.o:
37
38 $ ls $(DIR)/$(OBJECT)-in.o
39
40 which includes all compiled sources described
41
42
43 Build makefiles
44 ---------------
45
46 The user supplies 'Build' makefiles that conta
47 the build to nested directories.
48
49 Assume we have the following project structure
50
51 ex/a.c
52 /b.c
53 /c.c
54 /d.c
55 /arch/e.c
56 /arch/f.c
57
58 Out of which you build the 'ex' binary ' and t
59
60 'ex' - consists of 'a.o', 'b.o' and lib
61 'libex.a' - consists of 'c.o', 'd.o', 'e.o'
62
63 The build framework does not create the 'ex' a
64 only prepares proper objects to be compiled an
65
66 To follow the above example, the user provides
67
68 ex/Build:
69 ex-y += a.o
70 ex-y += b.o
71 ex-y += b.o # duplicates in the lists are
72
73 libex-y += c.o
74 libex-y += d.o
75 libex-y += arch/
76
77 ex/arch/Build:
78 libex-y += e.o
79 libex-y += f.o
80
81 and runs:
82
83 $ make -f tools/build/Makefile.build dir=. o
84 $ make -f tools/build/Makefile.build dir=. o
85
86 which creates the following objects:
87
88 ex/ex-in.o
89 ex/libex-in.o
90
91 that contain request objects names in Build fi
92
93 It's only a matter of 2 single commands to cre
94
95 $ ar rcs libex.a libex-in.o
96 $ gcc -o ex ex-in.o libex.a
97
98 You can check the 'ex' example in 'tools/build
99
100
101 Makefile.include
102 ----------------
103
104 The tools/build/Makefile.include makefile coul
105 via user makefiles to get usefull definitions.
106
107 It defines following interface:
108
109 - build macro definition:
110 build := -f $(srctree)/tools/build/Makef
111
112 to make it easier to invoke build like:
113 make $(build)=ex
114
115
116 Fixdep
117 ------
118 It is necessary to build the fixdep helper bef
119 The Makefile.include file adds the fixdep targ
120 invoked by the user.
121
122
123 Rules
124 -----
125
126 The build framework provides standard compilat
127 compilation.
128
129 It's possible to include special rule if neede
130 code generation).
131
132
133 CFLAGS
134 ------
135
136 It's possible to alter the standard object C f
137
138 CFLAGS_perf.o += '...' - adds CFLAGS
139 CFLAGS_gtk += '...' - adds CFLAGS
140 CFLAGS_REMOVE_perf.o += '...' - removes CFL
141 CFLAGS_REMOVE_gtk += '...' - removes CFL
142
143 This C flags changes has the scope of the Buil
144
145
146 Dependencies
147 ------------
148
149 For each built object file 'a.o' the '.a.cmd'
150
151 - Command line used to built that object
152 (for each object)
153
154 - Dependency rules generated by 'gcc -Wp,-MD
155 (for compiled object)
156
157 All existing '.cmd' files are included in the
158 the dependencies and trigger a rebuild when ne
159
160
161 Single rules
162 ------------
163
164 It's possible to build single object file by c
165
166 $ make util/map.o # objects
167 $ make util/map.i # preprocessor
168 $ make util/map.s # assembly
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