linux-kernel - Re: [PATCH 10/10] powerpc: select DYNAMIC_DEBUG_RELATIVE

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Date:   Tue, 23 Apr 2019 17:37:33 +0200
From:   Christophe Leroy <christophe.leroy@....fr>
To:     Rasmus Villemoes <linux@...musvillemoes.dk>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linuxppc-dev@...ts.ozlabs.org
Cc:     Jason Baron <jbaron@...mai.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 10/10] powerpc: select DYNAMIC_DEBUG_RELATIVE_POINTERS for
 PPC64



Le 09/04/2019 à 23:25, Rasmus Villemoes a écrit :
> Similar to GENERIC_BUG_RELATIVE_POINTERS, one can now relativize the
> four const char* members of struct _ddebug, thus saving 16 bytes per
> instance (one for each pr_debug(), dev_debug() etc. in a
> CONFIG_DYNAMIC_DEBUG kernel). The asm-generic implementation seems to
> work out-of-the-box, though this is only compile-tested.
> 
> Signed-off-by: Rasmus Villemoes <linux@...musvillemoes.dk>
> ---
>   arch/powerpc/Kconfig            | 1 +
>   arch/powerpc/include/asm/Kbuild | 1 +
>   2 files changed, 2 insertions(+)
> 
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 2d0be82c3061..6821c8ae1d62 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -155,6 +155,7 @@ config PPC
>   	select BUILDTIME_EXTABLE_SORT
>   	select CLONE_BACKWARDS
>   	select DCACHE_WORD_ACCESS		if PPC64 && CPU_LITTLE_ENDIAN
> +	select DYNAMIC_DEBUG_RELATIVE_POINTERS	if PPC64

Why only PPC64 ? Won't it work with PPC32 ? Or would it be 
counter-performant on 32 bits ?

Christophe

>   	select DYNAMIC_FTRACE			if FUNCTION_TRACER
>   	select EDAC_ATOMIC_SCRUB
>   	select EDAC_SUPPORT
> diff --git a/arch/powerpc/include/asm/Kbuild b/arch/powerpc/include/asm/Kbuild
> index a0c132bedfae..f332e202192a 100644
> --- a/arch/powerpc/include/asm/Kbuild
> +++ b/arch/powerpc/include/asm/Kbuild
> @@ -3,6 +3,7 @@ generated-y += syscall_table_64.h
>   generated-y += syscall_table_c32.h
>   generated-y += syscall_table_spu.h
>   generic-y += div64.h
> +generic-y += dynamic_debug.h
>   generic-y += export.h
>   generic-y += irq_regs.h
>   generic-y += local64.h
>