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author | 2015-08-04 12:17:53 -0700 | |
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committer | 2015-08-04 15:44:42 -0700 | |
commit | 9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00 (patch) | |
tree | 1c9cafbcd35f783a87880a10f85d1a060db1a563 /kernel/tools/build/Documentation/Build.txt | |
parent | 98260f3884f4a202f9ca5eabed40b1354c489b29 (diff) |
Add the rt linux 4.1.3-rt3 as base
Import the rt linux 4.1.3-rt3 as OPNFV kvm base.
It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and
the base is:
commit 0917f823c59692d751951bf5ea699a2d1e2f26a2
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Sat Jul 25 12:13:34 2015 +0200
Prepare v4.1.3-rt3
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
We lose all the git history this way and it's not good. We
should apply another opnfv project repo in future.
Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423
Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>
Diffstat (limited to 'kernel/tools/build/Documentation/Build.txt')
-rw-r--r-- | kernel/tools/build/Documentation/Build.txt | 139 |
1 files changed, 139 insertions, 0 deletions
diff --git a/kernel/tools/build/Documentation/Build.txt b/kernel/tools/build/Documentation/Build.txt new file mode 100644 index 000000000..00ad2d608 --- /dev/null +++ b/kernel/tools/build/Documentation/Build.txt @@ -0,0 +1,139 @@ +Build Framework +=============== + +The perf build framework was adopted from the kernel build system, hence the +idea and the way how objects are built is the same. + +Basically the user provides set of 'Build' files that list objects and +directories to nest for specific target to be build. + +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 +---------------------------- + +The build framework consists of 2 Makefiles: + + Build.include + Makefile.build + +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) + +where: + + KSRC - is the path to kernel sources + DIR - is the path to the project to be built + OBJECT - is the name of the build object + +When succefully finished the $(DIR) directory contains the final object file +called $(OBJECT)-in.o: + + $ ls $(DIR)/$(OBJECT)-in.o + +which includes all compiled sources described in 'Build' makefiles. + +a) Build makefiles +------------------ + +The user supplies 'Build' makefiles that contains a objects list, and connects +the build to nested directories. + +Assume we have the following project structure: + + ex/a.c + /b.c + /c.c + /d.c + /arch/e.c + /arch/f.c + +Out of which you build the 'ex' binary ' and the 'libex.a' library: + + 'ex' - consists of 'a.o', 'b.o' and libex.a + 'libex.a' - consists of 'c.o', 'd.o', 'e.o' and 'f.o' + +The build framework does not create the 'ex' and 'libex.a' binaries for you, it +only prepares proper objects to be compiled and grouped together. + +To follow the above example, the user provides following 'Build' files: + + ex/Build: + ex-y += a.o + ex-y += b.o + + libex-y += c.o + libex-y += d.o + libex-y += arch/ + + ex/arch/Build: + libex-y += e.o + libex-y += f.o + +and runs: + + $ make -f tools/build/Makefile.build dir=. obj=ex + $ make -f tools/build/Makefile.build dir=. obj=libex + +which creates the following objects: + + ex/ex-in.o + ex/libex-in.o + +that contain request objects names in Build files. + +It's only a matter of 2 single commands to create the final binaries: + + $ ar rcs libex.a libex-in.o + $ gcc -o ex ex-in.o libex.a + +You can check the 'ex' example in 'tools/build/tests/ex' for more details. + +b) Rules +-------- + +The build framework provides standard compilation rules to handle .S and .c +compilation. + +It's possible to include special rule if needed (like we do for flex or bison +code generation). + +c) CFLAGS +--------- + +It's possible to alter the standard object C flags in the following way: + + CFLAGS_perf.o += '...' - alters CFLAGS for perf.o object + CFLAGS_gtk += '...' - alters CFLAGS for gtk build object + +This C flags changes has the scope of the Build makefile they are defined in. + + +d) Dependencies +--------------- + +For each built object file 'a.o' the '.a.cmd' is created and holds: + + - Command line used to built that object + (for each object) + + - Dependency rules generated by 'gcc -Wp,-MD,...' + (for compiled object) + +All existing '.cmd' files are included in the Build process to follow properly +the dependencies and trigger a rebuild when necessary. + + +e) Single rules +--------------- + +It's possible to build single object file by choice, like: + + $ make util/map.o # objects + $ make util/map.i # preprocessor + $ make util/map.s # assembly |