[Buildroot] [PATCH] package/libunwind: disable for x86 with musl

[Yann E. MORIN <yann.morin.1998@free.fr>]

Romain, All,

On 2017-04-17 19:37 +0200, Romain Naour spake thusly:
> libunwind use sigreturn() and setcontext() while building for x86 [1]
> but this function is not available with musl [2].
> 
> This throw a warning during libunwind build:
> In file included from x86/Los-linux.c:4:0:
> x86/Gos-linux.c: In function ?_ULx86_local_resume?:
> x86/Gos-linux.c:298:7: warning: implicit declaration of function ?sigreturn? [-Wimplicit-function-declaration]
>       sigreturn (sc);
>       ^
> But any program trying to link against libunwind-generic.so or
> libunwind.so fail to build:
> [...]/usr/lib/libunwind-generic.so: undefined reference to `sigreturn'
> [...]/usr/lib/libunwind-generic.so: undefined reference to `setcontext'
> collect2: error: ld returned 1 exit status
> 
> Disable libunwind for x86 target when musl is used.
> 
> Reported upstream by Waldemar [3]
> 
> [1] http://git.savannah.gnu.org/gitweb/?p=libunwind.git;a=blob;f=src/x86/Gos-linux.c;h=17aebc2974af50eb0bf8292689b2ed22a4c97866;hb=HEAD#l299
> [2] http://openwall.com/lists/musl/2016/02/04/3
> [3] http://lists.nongnu.org/archive/html/libunwind-devel/2017-04/msg00030.html
> 
> Signed-off-by: Romain Naour <romain.naour@gmail.com>
> Cc: "Yann E. MORIN" <yann.morin.1998@free.fr>
> Cc: Waldemar Brodkorb <wbx@openadk.org>

Reviewed-by: "Yann E. MORIN" <yann.morin.1998@free.fr>

Regards,
Yann E. MORIN.

> ---
> Patch rebased after http://patchwork.ozlabs.org/patch/751402/
> ---
>  package/libunwind/Config.in | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/package/libunwind/Config.in b/package/libunwind/Config.in
> index 2003e96..1a25317 100644
> --- a/package/libunwind/Config.in
> +++ b/package/libunwind/Config.in
> @@ -16,7 +16,7 @@ config BR2_PACKAGE_LIBUNWIND_ARCH_SUPPORTS
>  		(BR2_ARM_CPU_HAS_ARM || BR2_mips || BR2_mipsel || \
>  		 BR2_mips64 || BR2_mips64el || BR2_x86_64)
>  	default y if BR2_TOOLCHAIN_USES_MUSL && \
> -		(BR2_ARM_CPU_HAS_ARM || BR2_i386 || BR2_x86_64)
> +		(BR2_ARM_CPU_HAS_ARM || BR2_x86_64)
>  
>  config BR2_PACKAGE_LIBUNWIND
>  	bool "libunwind"
> -- 
> 2.9.3
> 

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