path: root/scripts/Makefile.lib
diff options
authorMasahiro Yamada <>2020-07-07 18:21:16 +0900
committerMasahiro Yamada <>2020-08-10 01:32:59 +0900
commit15d5761ad31dfb194ebe76554e6af0437eb20424 (patch)
treeb2fdcab9a5bb39085f306ad089f17beeb00dd074 /scripts/Makefile.lib
parent3ec8a5b33deacdeca4bef24fb15498a975e875ba (diff)
kbuild: introduce ccflags-remove-y and asflags-remove-y
CFLAGS_REMOVE_<file>.o filters out flags when compiling a particular object, but there is no convenient way to do that for every object in a directory. Add ccflags-remove-y and asflags-remove-y to make it easily. Use ccflags-remove-y to clean up some Makefiles. The add/remove order works as follows: [1] KBUILD_CFLAGS specifies compiler flags used globally [2] ccflags-y adds compiler flags for all objects in the current Makefile [3] ccflags-remove-y removes compiler flags for all objects in the current Makefile (New feature) [4] CFLAGS_<file> adds compiler flags per file. [5] CFLAGS_REMOVE_<file> removes compiler flags per file. Having [3] before [4] allows us to remove flags from most (but not all) objects in the current Makefile. For example, kernel/trace/Makefile removes $(CC_FLAGS_FTRACE) from all objects in the directory, then adds it back to trace_selftest_dynamic.o and CFLAGS_trace_kprobe_selftest.o The same applies to lib/livepatch/Makefile. Please note ccflags-remove-y has no effect to the sub-directories. In contrast, the previous notation got rid of compiler flags also from all the sub-directories. The following are not affected because they have no sub-directories: arch/arm/boot/compressed/ arch/powerpc/xmon/ arch/sh/ kernel/trace/ However, lib/ has several sub-directories. To keep the behavior, I added ccflags-remove-y to all Makefiles in subdirectories of lib/, except the following: lib/vdso/Makefile - Kbuild does not descend into this Makefile lib/raid/test/Makefile - This is not used for the kernel build I think commit 2464a609ded0 ("ftrace: do not trace library functions") excluded too much. In the next commit, I will remove ccflags-remove-y from the sub-directories of lib/. Suggested-by: Sami Tolvanen <> Signed-off-by: Masahiro Yamada <> Acked-by: Steven Rostedt (VMware) <> Acked-by: Michael Ellerman <> (powerpc) Acked-by: Brendan Higgins <> (KUnit) Tested-by: Anders Roxell <>
Diffstat (limited to 'scripts/Makefile.lib')
1 files changed, 8 insertions, 6 deletions
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 8fa9aa2c9fca..5cfd377778b4 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -111,12 +111,14 @@ basename_flags = -DKBUILD_BASENAME=$(call name-fix,$(basetarget))
modname_flags = -DKBUILD_MODNAME=$(call name-fix,$(modname))
modfile_flags = -DKBUILD_MODFILE=$(call stringify,$(modfile))
-orig_c_flags = $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) \
- $(ccflags-y) $(CFLAGS_$(target-stem).o)
-_c_flags = $(filter-out $(CFLAGS_REMOVE_$(target-stem).o), $(orig_c_flags))
-orig_a_flags = $(KBUILD_CPPFLAGS) $(KBUILD_AFLAGS) \
- $(asflags-y) $(AFLAGS_$(target-stem).o)
-_a_flags = $(filter-out $(AFLAGS_REMOVE_$(target-stem).o), $(orig_a_flags))
+_c_flags = $(filter-out $(CFLAGS_REMOVE_$(target-stem).o), \
+ $(filter-out $(ccflags-remove-y), \
+ $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) $(ccflags-y)) \
+ $(CFLAGS_$(target-stem).o))
+_a_flags = $(filter-out $(AFLAGS_REMOVE_$(target-stem).o), \
+ $(filter-out $(asflags-remove-y), \
+ $(KBUILD_CPPFLAGS) $(KBUILD_AFLAGS) $(asflags-y)) \
+ $(AFLAGS_$(target-stem).o))
_cpp_flags = $(KBUILD_CPPFLAGS) $(cppflags-y) $(CPPFLAGS_$(target-stem).lds)