[Buildroot] [PATCH] package/mono: fix undefined reference to tls

[Thomas Petazzoni <thomas.petazzoni@free-electrons.com>]

Hello,

Thanks for investigating this issue!

On Thu,  8 Sep 2016 10:51:07 +0200, Angelo Compagnucci wrote:
> This commit fixes the nasty undefined reference to tls bug experienced with musl.
> 
> Fixes:
> http://autobuild.buildroot.net/results/048f04488cb8c7f4c32b828aa5214ebc22ba0153
> Signed-off-by: Angelo Compagnucci <angelo.compagnucci@gmail.com>
> ---
>  package/mono/mono.mk | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/package/mono/mono.mk b/package/mono/mono.mk
> index 3d0b9bc..de4f16b 100644
> --- a/package/mono/mono.mk
> +++ b/package/mono/mono.mk
> @@ -26,6 +26,10 @@ MONO_CONF_OPTS = --disable-gtk-doc \
>  	--disable-mcs-build \
>  	--enable-static
>  
> +ifeq ($(BR2_TOOLCHAIN_USES_MUSL),y)
> +MONO_CONF_OPTS += --with-tls=pthread
> +endif

Hum, that's interesting. Do you have more details about what this
--with-tls option is doing?

Is --with-tls related to Thread Local Storage provided by the compiler ?

Indeed, TLS support in gcc was disabled for musl toolchains until
recently (i.e until commit
https://git.buildroot.org/buildroot/commit/package/gcc?id=1bd02bc230e1b3b22ca3eb23fb3dcb91b878283a).

Since the toolchain that was causing the build failure was built
*prior* to this commit, maybe this commit fixes the issue, as it would
make musl toolchains have TLS support enabled in gcc.

Could you test this using the internal toolchain backend, and see if
without your fix the problem isn't already fixed? If that's the case,
I'll simply rebuild the pre-built toolchains.

Thanks,

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com