4 The perf build framework was adopted from the kernel build system, hence the
5 idea and the way how objects are built is the same.
7 Basically the user provides set of 'Build' files that list objects and
8 directories to nest for specific target to be build.
10 Unlike the kernel we don't have a single build object 'obj-y' list that where
11 we setup source objects, but we support more. This allows one 'Build' file to
12 carry a sources list for multiple build objects.
15 Build framework makefiles
16 -------------------------
18 The build framework consists of 2 Makefiles:
23 While the 'Build.include' file contains just some generic definitions, the
24 'Makefile.build' file is the makefile used from the outside. It's
25 interface/usage is following:
27 $ make -f tools/build/Makefile.build srctree=$(KSRC) dir=$(DIR) obj=$(OBJECT)
31 KSRC - is the path to kernel sources
32 DIR - is the path to the project to be built
33 OBJECT - is the name of the build object
35 When succefully finished the $(DIR) directory contains the final object file
36 called $(OBJECT)-in.o:
38 $ ls $(DIR)/$(OBJECT)-in.o
40 which includes all compiled sources described in 'Build' makefiles.
46 The user supplies 'Build' makefiles that contains a objects list, and connects
47 the build to nested directories.
49 Assume we have the following project structure:
58 Out of which you build the 'ex' binary ' and the 'libex.a' library:
60 'ex' - consists of 'a.o', 'b.o' and libex.a
61 'libex.a' - consists of 'c.o', 'd.o', 'e.o' and 'f.o'
63 The build framework does not create the 'ex' and 'libex.a' binaries for you, it
64 only prepares proper objects to be compiled and grouped together.
66 To follow the above example, the user provides following 'Build' files:
71 ex-y += b.o # duplicates in the lists are allowed
83 $ make -f tools/build/Makefile.build dir=. obj=ex
84 $ make -f tools/build/Makefile.build dir=. obj=libex
86 which creates the following objects:
91 that contain request objects names in Build files.
93 It's only a matter of 2 single commands to create the final binaries:
95 $ ar rcs libex.a libex-in.o
96 $ gcc -o ex ex-in.o libex.a
98 You can check the 'ex' example in 'tools/build/tests/ex' for more details.
104 The tools/build/Makefile.include makefile could be included
105 via user makefiles to get usefull definitions.
107 It defines following interface:
109 - build macro definition:
110 build := -f $(srctree)/tools/build/Makefile.build dir=. obj
112 to make it easier to invoke build like:
118 It is necessary to build the fixdep helper before invoking the build.
119 The Makefile.include file adds the fixdep target, that could be
126 The build framework provides standard compilation rules to handle .S and .c
129 It's possible to include special rule if needed (like we do for flex or bison
136 It's possible to alter the standard object C flags in the following way:
138 CFLAGS_perf.o += '...' - adds CFLAGS for perf.o object
139 CFLAGS_gtk += '...' - adds CFLAGS for gtk build object
140 CFLAGS_REMOVE_perf.o += '...' - removes CFLAGS for perf.o object
141 CFLAGS_REMOVE_gtk += '...' - removes CFLAGS for gtk build object
143 This C flags changes has the scope of the Build makefile they are defined in.
149 For each built object file 'a.o' the '.a.cmd' is created and holds:
151 - Command line used to built that object
154 - Dependency rules generated by 'gcc -Wp,-MD,...'
155 (for compiled object)
157 All existing '.cmd' files are included in the Build process to follow properly
158 the dependencies and trigger a rebuild when necessary.
164 It's possible to build single object file by choice, like:
166 $ make util/map.o # objects
167 $ make util/map.i # preprocessor
168 $ make util/map.s # assembly