[Buildroot] [PATCH v2] erlang: selectively enable libatomic_ops

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

Frank, All,

On 2014-12-22 19:53 -0500, Frank Hunleth spake thusly:
> Erlang can use either the system libatomic_ops or its own version.
> However, if using the system version, it must find implementations for
> AO_compare_and_swap() and other calls.  Since these are not available on
> ARM versions before armv6+, selectively enable the use of the system
> libatomic_ops.
> 
> Fixes:
>   http://autobuild.buildroot.net/results/eba/eba5bf85e9ff98916cd3638b5f13ab5bd54564d8/
>   http://autobuild.buildroot.net/results/c74/c743cfca629fb332bbb1327cf4ea360f0a4e4bfe/
>   http://autobuild.buildroot.net/results/095/095348d4d309c2a408a3b297b4325348ed1dd7e8/
> 
> Signed-off-by: Frank Hunleth <fhunleth@troodon-software.com>

I've sent an alternate solution to this libatomic_ops issue:
    http://patchwork.ozlabs.org/patch/425174/

This is much simpler, Buildroot-wise, as it essentially patches erlang,
so that it properly use libatomic_ops.

This is the result of a past discussion with Thomas P. on IRC, where he
pointed me to a patch we have against libunwind, that does require CAS
too, and for which we add `#define AO_REQUIRE_CAS', as instructed in the
libatomic_ops documentation.

Could you please test that new patch and report on it, please?

Thanks!

Regards,
Yann E. MORIN.

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