As a Kernel developer, I make heavy use of "make targz-pkg" in order
to locally compile and remotely install my development Kernels. The
nice feature I rely on is that after a normal "make", "make targz-pkg"
only generates the tarball without having to recompile everything.
That was true until commit f28bc3c32c05 ("tracing: Handle
CC_FLAGS_FTRACE more accurately"). After it, running "make targz-pkg"
after "make" will recompile the whole Kernel tree, making my
development workflow much slower.
The Kernel is choosing to recompile everything because it claims the
command line has changed. A diff of the .cmd files show a repeated
-mfentry in one of the files. It seems that something on make
targz-pkg triggers the double -mfentry but not the double -pg.
So this patch attempts to deal with that problem by handling -mfentry
and others just like we handle -pg: don't append them if
CC_FLAGS_FTRACE is already defined. I'm not a Makefile expert and so I
can't claim this won't break anything else, hopefully if this patch
gets applied it will have a Reviewed-by tag from some actual Makefile
expert. I can claim this patch fixes the specific regression I
reported.
Fixes: commit f28bc3c32c05 ("tracing: Handle CC_FLAGS_FTRACE more
accurately")
Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Cc: Michal Marek <michal.lkml@xxxxxxxxxxx>
Cc: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Cc: linux-kbuild@xxxxxxxxxxxxxxx
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@xxxxxxxxx>
---
Makefile | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/Makefile b/Makefile
index 19948e556941..2c8df481b4f1 100644
--- a/Makefile
+++ b/Makefile
@@ -755,28 +755,30 @@ KBUILD_CFLAGS += $(call cc-option, -femit-struct-debug-baseonly) \
endif
ifdef CONFIG_FUNCTION_TRACER
-ifndef CC_FLAGS_FTRACE
-CC_FLAGS_FTRACE := -pg
-endif
+cc_flags_ftrace_ := -pg
ifdef CONFIG_FTRACE_MCOUNT_RECORD
# gcc 5 supports generating the mcount tables directly
ifeq ($(call cc-option-yn,-mrecord-mcount),y)
- CC_FLAGS_FTRACE += -mrecord-mcount
+ cc_flags_ftrace_ += -mrecord-mcount
export CC_USING_RECORD_MCOUNT := 1
endif
ifdef CONFIG_HAVE_NOP_MCOUNT
ifeq ($(call cc-option-yn, -mnop-mcount),y)
- CC_FLAGS_FTRACE += -mnop-mcount
+ cc_flags_ftrace_ += -mnop-mcount
CC_FLAGS_USING += -DCC_USING_NOP_MCOUNT
endif
endif
endif
ifdef CONFIG_HAVE_FENTRY
ifeq ($(call cc-option-yn, -mfentry),y)
- CC_FLAGS_FTRACE += -mfentry
+ cc_flags_ftrace_ += -mfentry
CC_FLAGS_USING += -DCC_USING_FENTRY
endif
endif
+
+ifndef CC_FLAGS_FTRACE
+ CC_FLAGS_FTRACE := $(cc_flags_ftrace_)
+endif
export CC_FLAGS_FTRACE
KBUILD_CFLAGS += $(CC_FLAGS_FTRACE) $(CC_FLAGS_USING)
KBUILD_AFLAGS += $(CC_FLAGS_USING)
--
2.17.1
