[PATCH 1/4] kbuild: Create new CFLAGS_REMOVE_(basename).o option

[Steven Rostedt]

We currently have a way to add special CFLAGS to code, but we do not have a 
way to remove them if needed.

With the case of ftrace, some files should simply not be profiled. Adding
the -pg flag to these files is simply a waste, and adding "notrace" to each
and every function is ugly.

Currently we put in "Makefile turd" [1] to stop the compiler from adding -pg
to certain files. This was clumsy and awkward.

This patch now adds the revese of CFLAGS_(basename).o with
CFLAGS_REMOVE_(basename).o.  This allows developers to prevent certain
CFLAGS from being used to compile files. For example, we can now do

CFLAGS_REMOVE_string.o = -pg

to remove the -pg option from the string.o file in the lib directory.

Note: a space delimited list of options may be added to the REMOVE macro.

[1] - what David Miller called the workaronud to remove -pg

Signed-off-by: Steven Rostedt <srostedt@xxxxxxxxxx>
---
 scripts/Makefile.lib |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Index: linux-sched-devel.git/scripts/Makefile.lib
===================================================================
--- linux-sched-devel.git.orig/scripts/Makefile.lib	2008-05-14 18:12:22.000000000 -0700
+++ linux-sched-devel.git/scripts/Makefile.lib	2008-05-14 18:12:26.000000000 -0700
@@ -96,7 +96,8 @@ basename_flags = -D"KBUILD_BASENAME=KBUI
 modname_flags  = $(if $(filter 1,$(words $(modname))),\
                  -D"KBUILD_MODNAME=KBUILD_STR($(call name-fix,$(modname)))")
 
-_c_flags       = $(KBUILD_CFLAGS) $(ccflags-y) $(CFLAGS_$(basetarget).o)
+orig_c_flags   = $(KBUILD_CFLAGS) $(ccflags-y) $(CFLAGS_$(basetarget).o)
+_c_flags       = $(filter-out $(CFLAGS_REMOVE_$(basetarget).o), $(orig_c_flags))
 _a_flags       = $(KBUILD_AFLAGS) $(asflags-y) $(AFLAGS_$(basetarget).o)
 _cpp_flags     = $(KBUILD_CPPFLAGS) $(cppflags-y) $(CPPFLAGS_$(@F))
 

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