Re: [PATCH 01/10] Makefile: Add optionCONFIG_DISABLE_GCC_AUTOMATIC_INLINING

From: Sam Ravnborg
Date: Sat Sep 08 2012 - 17:44:48 EST


On Sat, Sep 08, 2012 at 05:47:50PM -0300, Ezequiel Garcia wrote:
> As its name suggest this option prevents gcc from auto inlining
> small functions. This is very important if one wants to obtain
> traces with accurate call sites.
>
> Without this option, gcc will collapse some small functions,
> even when not marked as 'inline' thus making impossible to
> correlate the trace caller address to the real function it belongs.
>
> Of course, the resultant kernel is slower and slightly smaller,
> but that's not an issue if the focus is on tracing accuracy.
>
> Cc: Michal Marek <mmarek@xxxxxxx>
> Signed-off-by: Ezequiel Garcia <elezegarcia@xxxxxxxxx>
> ---
> Makefile | 4 ++++
> lib/Kconfig.debug | 11 +++++++++++
> 2 files changed, 15 insertions(+), 0 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index ddf5be9..df6045a 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -561,6 +561,10 @@ else
> KBUILD_CFLAGS += -O2
> endif
>
> +ifdef CONFIG_DISABLE_GCC_AUTOMATIC_INLINING
> +KBUILD_CFLAGS += -fno-inline-small-functions
> +endif
> +
> include $(srctree)/arch/$(SRCARCH)/Makefile
>
> ifdef CONFIG_READABLE_ASM
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index 2403a63..c8fd50f 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -1265,6 +1265,17 @@ config LATENCYTOP
> source mm/Kconfig.debug
> source kernel/trace/Kconfig
>
> +config DISABLE_GCC_AUTOMATIC_INLINING
> + bool "Disable gcc automatic inlining"

Could we please call this option for:
config CC_DISABLE_AUTOMATIC_INLINING

We have at least a few other options following that naming scheme.
And today we have no options named *GCC_*

Sam
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