On Tue, 2010-02-02 at 14:40 -0800, a...@linux-foundation.org wrote:
> From: Andi Kleen <a...@firstfloor.org>
>
> Better dwarf2 unwind information is a good thing, it allows better
> debugging with kgdb and crash and helps systemtap.
>
> Commit 003086497f07f7f1e67c0c295e261740f822b377 ("Build with
> -fno-dwarf2-cfi-asm") disabled some CFI information globally to work
> around a module loader bug on powerpc.
>
> But this disables the better unwind tables for all architectures, not just
> powerpc. Move the workaround to powerpc and also add a suitable comment
> that's it really a workaround.
>
> This improves dwarf2 unwind tables on x86 at least.
>
> Signed-off-by: Andi Kleen <a...@linux.intel.com>
> Cc: Kyle McMartin <k...@mcmartin.ca>
Acked-by: Benjamin Herrenschmidt <b...@kernel.crashing.org>
Do you want me to carry that in powerpc-next ?
Cheers,
Ben.
> Cc: Michal Marek <mma...@suse.cz>
> Signed-off-by: Andrew Morton <a...@linux-foundation.org>
> ---
>
> Makefile | 3 ---
> arch/powerpc/Makefile | 5 +++++
> 2 files changed, 5 insertions(+), 3 deletions(-)
>
> diff -puN Makefile~kbuild-move-fno-dwarf2-cfi-asm-to-powerpc-only Makefile
> --- a/Makefile~kbuild-move-fno-dwarf2-cfi-asm-to-powerpc-only
> +++ a/Makefile
> @@ -579,9 +579,6 @@ KBUILD_CFLAGS += $(call cc-option,-Wno-p
> # disable invalid "can't wrap" optimizations for signed / pointers
> KBUILD_CFLAGS += $(call cc-option,-fno-strict-overflow)
>
> -# revert to pre-gcc-4.4 behaviour of .eh_frame
> -KBUILD_CFLAGS += $(call cc-option,-fno-dwarf2-cfi-asm)
> -
> # conserve stack if available
> KBUILD_CFLAGS += $(call cc-option,-fconserve-stack)
>
> diff -puN
> arch/powerpc/Makefile~kbuild-move-fno-dwarf2-cfi-asm-to-powerpc-only
> arch/powerpc/Makefile
> --- a/arch/powerpc/Makefile~kbuild-move-fno-dwarf2-cfi-asm-to-powerpc-only
> +++ a/arch/powerpc/Makefile
> @@ -112,6 +112,11 @@ KBUILD_CFLAGS += $(call cc-option,-mspe=
> # kernel considerably.
> KBUILD_CFLAGS += $(call cc-option,-funit-at-a-time)
>
> +# FIXME: the module load should be taught about the additional relocs
> +# generated by this.
> +# revert to pre-gcc-4.4 behaviour of .eh_frame
> +KBUILD_CFLAGS += $(call cc-option,-fno-dwarf2-cfi-asm)
> +
> # Never use string load/store instructions as they are
> # often slow when they are implemented at all
> KBUILD_CFLAGS += -mno-string
> _
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