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Message-ID: <baf39eb0-3115-eb25-9378-f4f99a0a00b3@arm.com>
Date:   Mon, 8 Aug 2022 10:49:25 +0100
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Subject: Re: [PATCH] ARM: disable FDPIC ABI
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To:     Ben Wolsieffer <ben.wolsieffer@hefring.com>
Cc:     Russell King <linux@armlinux.org.uk>,
        Arnd Bergmann <arnd@arndb.de>,
        Ard Biesheuvel <ardb@kernel.org>,
        Masahiro Yamada <masahiroy@kernel.org>,
        "Russell King (Oracle)" <rmk+kernel@armlinux.org.uk>,
        Linus Walleij <linus.walleij@linaro.org>,
        Nick Hawkins <nick.hawkins@hpe.com>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
References: <20220801191721.1253291-1-Ben.Wolsieffer@hefring.com>
From:   Vladimir Murzin <vladimir.murzin@arm.com>
In-Reply-To: <20220801191721.1253291-1-Ben.Wolsieffer@hefring.com>
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On 8/1/22 20:17, Ben Wolsieffer wrote:
> When building with an arm-*-uclinuxfdpiceabi toolchain, the FDPIC ABI is
> enabled by default but should not be used to build the kernel.
> Therefore, pass -mno-fdpic if supported by the compiler.
> 
> Signed-off-by: Ben Wolsieffer <Ben.Wolsieffer@hefring.com>
> ---
>  arch/arm/Makefile | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/arch/arm/Makefile b/arch/arm/Makefile
> index c8e3633f5434..88be49b71d40 100644
> --- a/arch/arm/Makefile
> +++ b/arch/arm/Makefile
> @@ -22,6 +22,9 @@ GZFLAGS		:=-9
>  # Never generate .eh_frame
>  KBUILD_CFLAGS	+= $(call cc-option,-fno-dwarf2-cfi-asm)
>  
> +# Disable FDPIC ABI
> +KBUILD_CFLAGS	+= $(call cc-option,-mno-fdpic)
> +
>  # This should work on most of the modern platforms
>  KBUILD_DEFCONFIG := multi_v7_defconfig
>  

Without patch I'm getting

scripts/link-vmlinux.sh: line 52: 312779 Segmentation fault      (core dumped) ${ld} ${ldflags} -o ${output} ${wl}--whole-archive ${objs} ${wl}--no-whole-archive ${wl}--start-group ${libs} ${wl}--end-group $@ ${ldlibs}

So, FWIW:

Reviewed-by: Vladimir Murzin <vladimir.murzin@arm.com>
Tested-by: Vladimir Murzin <vladimir.murzin@arm.com>

Unless you get any other comments, please, drop it into RMK's patch system [1].
 
[1] https://www.armlinux.org.uk/developer/patches/

P.S. 
Extra thanks for Buildroot patches, they were handy to build FDPIC toolchain and
test the patch!

Cheers
Vladimir