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Subject: Re: [PATCH] powerpc: Kconfig: disable CONFIG_COMPAT for clang < 12
To:     Nick Desaulniers <ndesaulniers@google.com>,
        Michael Ellerman <mpe@ellerman.id.au>
Cc:     Segher Boessenkool <segher@kernel.crashing.org>,
        Fangrui Song <maskray@google.com>,
        Christophe Leroy <christophe.leroy@csgroup.eu>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
        clang-built-linux@googlegroups.com
References: <20210518205858.2440344-1-ndesaulniers@google.com>
From:   Nathan Chancellor <nathan@kernel.org>
Message-ID: <fe638f4e-4dea-2f5e-2193-2f8b63aaf7a8@kernel.org>
Date:   Tue, 18 May 2021 14:12:56 -0700
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On 5/18/2021 1:58 PM, Nick Desaulniers wrote:
> Until clang-12, clang would attempt to assemble 32b powerpc assembler in
> 64b emulation mode when using a 64b target triple with -m32, leading to
> errors during the build of the compat VDSO. Simply disable all of
> CONFIG_COMPAT; users should upgrade to the latest release of clang for
> proper support.
> 
> Link: https://github.com/ClangBuiltLinux/linux/issues/1160
> Link: https://github.com/llvm/llvm-project/commits/2288319733cd5f525bf7e24dece08bfcf9d0ff9e
> Link: https://groups.google.com/g/clang-built-linux/c/ayNmi3HoNdY/m/XJAGj_G2AgAJ
> Suggested-by: Nathan Chancellor <nathan@kernel.org>
> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>

Reviewed-by: Nathan Chancellor <nathan@kernel.org>

> ---
>   arch/powerpc/Kconfig | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index ce3f59531b51..2a02784b7ef0 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -289,6 +289,7 @@ config PANIC_TIMEOUT
>   config COMPAT
>   	bool "Enable support for 32bit binaries"
>   	depends on PPC64
> +	depends on !CC_IS_CLANG || CLANG_VERSION >= 120000
>   	default y if !CPU_LITTLE_ENDIAN
>   	select ARCH_WANT_OLD_COMPAT_IPC
>   	select COMPAT_OLD_SIGACTION
>