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authorMasahiro Yamada <masahiroy@kernel.org>2020-07-07 18:21:16 +0900
committerMasahiro Yamada <masahiroy@kernel.org>2020-08-10 01:32:59 +0900
commit15d5761ad31dfb194ebe76554e6af0437eb20424 (patch)
treeb2fdcab9a5bb39085f306ad089f17beeb00dd074 /lib/lz4
parent3ec8a5b33deacdeca4bef24fb15498a975e875ba (diff)
downloadlinux-15d5761ad31dfb194ebe76554e6af0437eb20424.tar.bz2
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 $(CC_FLAGS_FTRACE) from all objects in the directory, then adds it back to trace_selftest_dynamic.o and CFLAGS_trace_kprobe_selftest.o The same applies to lib/livepatch/Makefile. Please note ccflags-remove-y has no effect to the sub-directories. In contrast, the previous notation got rid of compiler flags also from all the sub-directories. The following are not affected because they have no sub-directories: arch/arm/boot/compressed/ arch/powerpc/xmon/ arch/sh/ kernel/trace/ However, lib/ has several sub-directories. To keep the behavior, I added ccflags-remove-y to all Makefiles in subdirectories of lib/, except the following: lib/vdso/Makefile - Kbuild does not descend into this Makefile lib/raid/test/Makefile - This is not used for the kernel build I think commit 2464a609ded0 ("ftrace: do not trace library functions") excluded too much. In the next commit, I will remove ccflags-remove-y from the sub-directories of lib/. Suggested-by: Sami Tolvanen <samitolvanen@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) Acked-by: Brendan Higgins <brendanhiggins@google.com> (KUnit) Tested-by: Anders Roxell <anders.roxell@linaro.org>
Diffstat (limited to 'lib/lz4')
-rw-r--r--lib/lz4/Makefile1
1 files changed, 1 insertions, 0 deletions
diff --git a/lib/lz4/Makefile b/lib/lz4/Makefile
index 5b42242afaa2..53da4cab7015 100644
--- a/lib/lz4/Makefile
+++ b/lib/lz4/Makefile
@@ -1,5 +1,6 @@
# SPDX-License-Identifier: GPL-2.0-only
ccflags-y += -O3
+ccflags-remove-$(CONFIG_FUNCTION_TRACER) += $(CC_FLAGS_FTRACE)
obj-$(CONFIG_LZ4_COMPRESS) += lz4_compress.o
obj-$(CONFIG_LZ4HC_COMPRESS) += lz4hc_compress.o