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SubjectRe: [PATCH 1/3] powerpc, Makefile: Make it possible to safely select CONFIG_FRAME_POINTER
On Fri, Mar 20, 2009 at 07:44:29PM +0300, Anton Vorontsov wrote:
> This patch introduces ARCH_HAS_NORMAL_FRAME_POINTERS Kconfig symbol.
> When defined, the top level Makefile won't add -fno-omit-frame-pointer
> cflag (the flag is useless in PowerPC kernels, and also makes gcc
> generate wrong code).
>
> Also move ARCH_WANT_FRAME_POINTERS's help text.
>
> Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>

Hi Anton - sorry for the late feedback.

1) The preferred naming for variables that are supposed to be selcted
are "HAVE_xxxx".
So in this case it would be:
HAVE_NORMAL_FRAME_POINTER

2) I do not really understand the interpretation of normal in this case,
can it be more specific?

Looking at your patch then if specified we use "-fomit-frame-pointer"
in the case where it is set.
So I read it like:

If arch has normal framepointer then we omit them - strange?

3) Indent in top-level MAkefile for new stuff is generally 8 spaces.
Do NOT use tabs as this would confuse make and rener assignmnet non-functional.

4) The individual "HAVE_* members should be sorted alphabetically in the arch
Kconfig file (which they seldomly are :-( )

Sam

> ---
> Makefile | 7 +++++--
> arch/powerpc/Kconfig | 1 +
> lib/Kconfig.debug | 16 ++++++++++------
> 3 files changed, 16 insertions(+), 8 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index 46c04c5..bf41b05 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -538,9 +538,12 @@ KBUILD_CFLAGS += $(call cc-option, -fno-stack-protector)
> endif
>
> ifdef CONFIG_FRAME_POINTER
> -KBUILD_CFLAGS += -fno-omit-frame-pointer -fno-optimize-sibling-calls
> + KBUILD_CFLAGS += -fno-optimize-sibling-calls
> + ifndef ARCH_HAS_NORMAL_FRAME_POINTERS
> + KBUILD_CFLAGS += -fno-omit-frame-pointer
> + endif
> else
> -KBUILD_CFLAGS += -fomit-frame-pointer
> + KBUILD_CFLAGS += -fomit-frame-pointer
> endif
>
> ifdef CONFIG_DEBUG_INFO
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 97f9a64..4587e66 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -113,6 +113,7 @@ config PPC
> select HAVE_FUNCTION_TRACER
> select HAVE_FUNCTION_GRAPH_TRACER
> select ARCH_WANT_OPTIONAL_GPIOLIB
> + select ARCH_HAS_NORMAL_FRAME_POINTERS
> select HAVE_IDE
> select HAVE_IOREMAP_PROT
> select HAVE_EFFICIENT_UNALIGNED_ACCESS
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index 4b63b6b..fc8cd1f 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -661,20 +661,24 @@ config DEBUG_NOTIFIERS
> This is a relatively cheap check but if you care about maximum
> performance, say N.
>
> -#
> -# Select this config option from the architecture Kconfig, if it
> -# it is preferred to always offer frame pointers as a config
> -# option on the architecture (regardless of KERNEL_DEBUG):
> -#
> config ARCH_WANT_FRAME_POINTERS
> bool
> help
> + Select this config option from the architecture Kconfig, if it
> + it is preferred to always offer frame pointers as a config
> + option on the architecture (regardless of KERNEL_DEBUG).
> +
> +config ARCH_HAS_NORMAL_FRAME_POINTERS
> + bool
> + help
> + Architectures should select this symbol if their ABI implies
> + having a frame pointer.
>
> config FRAME_POINTER
> bool "Compile the kernel with frame pointers"
> depends on DEBUG_KERNEL && \
> (CRIS || M68K || M68KNOMMU || FRV || UML || S390 || \
> - AVR32 || SUPERH || BLACKFIN || MN10300) || \
> + AVR32 || SUPERH || BLACKFIN || MN10300 || PPC) || \
> ARCH_WANT_FRAME_POINTERS
> default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
> help
> --
> 1.5.6.5
>


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