tools build: Add Makefile.include

To ease up build framework code setup for users.

More shared code will be added in the following patches.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1443004442-32660-2-git-send-email-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/build/Documentation/Build.txt

@@ -11,8 +11,9 @@ Unlike the kernel we don't have a single build object 'obj-y' list that where
 we setup source objects, but we support more. This allows one 'Build' file to
 carry a sources list for multiple build objects.
 
-a) Build framework makefiles
-----------------------------
+
+Build framework makefiles
+-------------------------
 
 The build framework consists of 2 Makefiles:
 
@@ -23,7 +24,7 @@ While the 'Build.include' file contains just some generic definitions, the
 'Makefile.build' file is the makefile used from the outside. It's
 interface/usage is following:
 
-  $ make -f tools/build/Makefile srctree=$(KSRC) dir=$(DIR) obj=$(OBJECT)
+  $ make -f tools/build/Makefile.build srctree=$(KSRC) dir=$(DIR) obj=$(OBJECT)
 
 where:
 
@@ -38,8 +39,9 @@ called $(OBJECT)-in.o:
 
 which includes all compiled sources described in 'Build' makefiles.
 
-a) Build makefiles
-------------------
+
+Build makefiles
+---------------
 
 The user supplies 'Build' makefiles that contains a objects list, and connects
 the build to nested directories.
@@ -95,8 +97,24 @@ It's only a matter of 2 single commands to create the final binaries:
 
 You can check the 'ex' example in 'tools/build/tests/ex' for more details.
 
-b) Rules
---------
+
+Makefile.include
+----------------
+
+The tools/build/Makefile.include makefile could be included
+via user makefiles to get usefull definitions.
+
+It defines following interface:
+
+  - build macro definition:
+      build := -f $(srctree)/tools/build/Makefile.build dir=. obj
+
+    to make it easier to invoke build like:
+      make $(build)=ex
+
+
+Rules
+-----
 
 The build framework provides standard compilation rules to handle .S and .c
 compilation.
@@ -104,8 +122,9 @@ compilation.
 It's possible to include special rule if needed (like we do for flex or bison
 code generation).
 
-c) CFLAGS
----------
+
+CFLAGS
+------
 
 It's possible to alter the standard object C flags in the following way:
 
@@ -115,8 +134,8 @@ It's possible to alter the standard object C flags in the following way:
 This C flags changes has the scope of the Build makefile they are defined in.
 
 
-d) Dependencies
----------------
+Dependencies
+------------
 
 For each built object file 'a.o' the '.a.cmd' is created and holds:
 
@@ -130,8 +149,8 @@ All existing '.cmd' files are included in the Build process to follow properly
 the dependencies and trigger a rebuild when necessary.
 
 
-e) Single rules
----------------
+Single rules
+------------
 
 It's possible to build single object file by choice, like:
 

tools/build/Makefile.include

+build := -f $(srctree)/tools/build/Makefile.build dir=. obj

tools/build/tests/ex/Makefile

@@ -3,7 +3,8 @@ export CC      := gcc
 export LD      := ld
 export AR      := ar
 
-build := -f $(srctree)/tools/build/Makefile.build dir=. obj
+include $(srctree)/tools/build/Makefile.include
+
 ex: ex-in.o libex-in.o
 	gcc -o $@ $^
 

tools/lib/api/Makefile

@@ -21,10 +21,10 @@ CFLAGS += -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64
 
 RM = rm -f
 
-build  := -f $(srctree)/tools/build/Makefile.build dir=. obj
 API_IN := $(OUTPUT)libapi-in.o
 
 export srctree OUTPUT CC LD CFLAGS V
+include $(srctree)/tools/build/Makefile.include
 
 all: $(LIBFILE)
 

tools/lib/bpf/Makefile

@@ -124,7 +124,7 @@ endif
 MAKEOVERRIDES=
 
 export srctree OUTPUT CC LD CFLAGS V
-build := -f $(srctree)/tools/build/Makefile.build dir=. obj
+include $(srctree)/tools/build/Makefile.include
 
 BPF_IN    := $(OUTPUT)libbpf-in.o
 LIB_FILE := $(addprefix $(OUTPUT),$(LIB_FILE))

tools/lib/lockdep/Makefile

@@ -94,7 +94,7 @@ else
 endif
 
 export srctree OUTPUT CC LD CFLAGS V
-build := -f $(srctree)/tools/build/Makefile.build dir=. obj
+include $(srctree)/tools/build/Makefile.include
 
 do_compile_shared_library =			\
 	($(print_shared_lib_compile)		\

tools/perf/Makefile.perf

@@ -297,7 +297,7 @@ strip: $(PROGRAMS) $(OUTPUT)perf
 PERF_IN := $(OUTPUT)perf-in.o
 
 export srctree OUTPUT RM CC LD AR CFLAGS V BISON FLEX AWK
-build := -f $(srctree)/tools/build/Makefile.build dir=. obj
+include $(srctree)/tools/build/Makefile.include
 
 $(PERF_IN): $(OUTPUT)PERF-VERSION-FILE $(OUTPUT)common-cmds.h FORCE
 	$(Q)$(MAKE) $(build)=perf