* [PATCH] kbuild: disable -ffunction-sections on gcc-4.7 with ftrace
@ 2016-12-16 9:24 Arnd Bergmann
2016-12-18 14:14 ` Namhyung Kim
0 siblings, 1 reply; 2+ messages in thread
From: Arnd Bergmann @ 2016-12-16 9:24 UTC (permalink / raw)
To: Michal Marek
Cc: Arnd Bergmann, Nicolas Pitre, Kees Cook, linux-kbuild, linux-kernel
When ftrace is enabled and we build with gcc-4.7 or older, we
get a warning for each file on architectures that select
CONFIG_LD_DEAD_CODE_DATA_ELIMINATION:
warning: -ffunction-sections disabled; it makes profiling impossible [enabled by default]
This turns off function sections in that specific case, leaving
it enabled for all other configurations.
Fixes: b67067f1176d ("kbuild: allow archs to select link dead code/data elimination")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
Makefile | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/Makefile b/Makefile
index 4fb4b889c862..7dfd0aa4f3f7 100644
--- a/Makefile
+++ b/Makefile
@@ -638,7 +638,11 @@ KBUILD_CFLAGS += $(call cc-option,-fno-delete-null-pointer-checks,)
KBUILD_CFLAGS += $(call cc-disable-warning,frame-address,)
ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
+ifdef CONFIG_FUNCTION_TRACER
+KBUILD_CFLAGS += $(call cc-ifversion, -ge,0409,$(call cc-option,-ffunction-sections,))
+else
KBUILD_CFLAGS += $(call cc-option,-ffunction-sections,)
+endif
KBUILD_CFLAGS += $(call cc-option,-fdata-sections,)
endif
--
2.9.0
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] kbuild: disable -ffunction-sections on gcc-4.7 with ftrace
2016-12-16 9:24 [PATCH] kbuild: disable -ffunction-sections on gcc-4.7 with ftrace Arnd Bergmann
@ 2016-12-18 14:14 ` Namhyung Kim
0 siblings, 0 replies; 2+ messages in thread
From: Namhyung Kim @ 2016-12-18 14:14 UTC (permalink / raw)
To: Arnd Bergmann
Cc: Michal Marek, Nicolas Pitre, Kees Cook, linux-kbuild, LKML, Namhyung Kim
Hi,
On Fri, Dec 16, 2016 at 6:24 PM, Arnd Bergmann <arnd@arndb.de> wrote:
> When ftrace is enabled and we build with gcc-4.7 or older, we
> get a warning for each file on architectures that select
> CONFIG_LD_DEAD_CODE_DATA_ELIMINATION:
>
> warning: -ffunction-sections disabled; it makes profiling impossible [enabled by default]
>
> This turns off function sections in that specific case, leaving
> it enabled for all other configurations.
>
> Fixes: b67067f1176d ("kbuild: allow archs to select link dead code/data elimination")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> Makefile | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/Makefile b/Makefile
> index 4fb4b889c862..7dfd0aa4f3f7 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -638,7 +638,11 @@ KBUILD_CFLAGS += $(call cc-option,-fno-delete-null-pointer-checks,)
> KBUILD_CFLAGS += $(call cc-disable-warning,frame-address,)
>
> ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
> +ifdef CONFIG_FUNCTION_TRACER
> +KBUILD_CFLAGS += $(call cc-ifversion, -ge,0409,$(call cc-option,-ffunction-sections,))
s/0409/0408/ ?
Thanks,
Namhyung
> +else
> KBUILD_CFLAGS += $(call cc-option,-ffunction-sections,)
> +endif
> KBUILD_CFLAGS += $(call cc-option,-fdata-sections,)
> endif
>
> --
> 2.9.0
>
^ permalink raw reply [flat|nested] 2+ messages in thread
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