From 15d5761ad31dfb194ebe76554e6af0437eb20424 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Tue, 7 Jul 2020 18:21:16 +0900 Subject: kbuild: introduce ccflags-remove-y and asflags-remove-y CFLAGS_REMOVE_.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_ adds compiler flags per file. [5] CFLAGS_REMOVE_ 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 $(CC_FLAGS_FTRACE) from all objects in the directory, then adds it back to trace_selftest_dynamic.o and CFLAGS_trace_kprobe_selftest.o The same applies to lib/livepatch/Makefile. Please note ccflags-remove-y has no effect to the sub-directories. In contrast, the previous notation got rid of compiler flags also from all the sub-directories. The following are not affected because they have no sub-directories: arch/arm/boot/compressed/ arch/powerpc/xmon/ arch/sh/ kernel/trace/ However, lib/ has several sub-directories. To keep the behavior, I added ccflags-remove-y to all Makefiles in subdirectories of lib/, except the following: lib/vdso/Makefile - Kbuild does not descend into this Makefile lib/raid/test/Makefile - This is not used for the kernel build I think commit 2464a609ded0 ("ftrace: do not trace library functions") excluded too much. In the next commit, I will remove ccflags-remove-y from the sub-directories of lib/. Suggested-by: Sami Tolvanen Signed-off-by: Masahiro Yamada Acked-by: Steven Rostedt (VMware) Acked-by: Michael Ellerman (powerpc) Acked-by: Brendan Higgins (KUnit) Tested-by: Anders Roxell --- scripts/Makefile.lib | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) (limited to 'scripts/Makefile.lib') diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib index 8fa9aa2c9fca..5cfd377778b4 100644 --- a/scripts/Makefile.lib +++ b/scripts/Makefile.lib @@ -111,12 +111,14 @@ basename_flags = -DKBUILD_BASENAME=$(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) # -- cgit