[Buildroot] [PATCH v2 1/1] LIBLO : bump version to 0.29

[Thomas Petazzoni <thomas.petazzoni@bootlin.com>]

Hello Alex,

On Sat, 10 Feb 2018 17:19:16 +0100, Alex Baldwin wrote:

> I  am not sure the best place to address this so please correct me :) I
> noticed that this patch failed with your submission as well as Matt
> Webber's, but for different reasons.
> 
> It seems that on yours
> http://autobuild.buildroot.net/results/71a6d7e02a50f6cb53c70c38e82e2a2ae8af13ea/build-end.log
> there is a warning about having to redirect <sys/poll.h> to <poll.h> in the
> file "server.c:54". This could be sorted with a simple patch, is it
> acceptable to patch for this?

Yes, it is acceptable. In addition to fixing this particular problem,
it would be nice to avoid using -Werror. Indeed, the problem here is
that this warning is treated as an error, causing a build failure.

While -Werror makes sense during development, it doesn't make much
sense for releases.

> On Matt's
> http://autobuild.buildroot.net/results/c8b/c8bed3a3fa7d2b2258f573cbfcb01af07419e0bf/build-end.log
> we fail because undefined reference to  __atomic_fetch_add_4 . I think a
> possible fix could be manually linking to libatomic. I am not entirely sure
> why, seems that some compilers are happy to find libatomic on their own and
> others aren't. Is this something that buildroot would normally patch for?

The libatomic situation depends on the architecture. On most
architectures, __atomic_fetch_add_4 is a compiler builtin, so you don't
need to link with libatomic.

However, on SPARC (which is the CPU architecture on which this build
failure occurs), libatomic is needed for __atomic_fetch_add_4.

You have two solutions to handle that:

 (1) Just pass LIBS="-latomic" in LIBLO_CONF_ENV when
     BR2_TOOLCHAIN_HAS_LIBATOMIC=y

 (2) Patch the configure.ac script so that it tests if linking with
     libatomic is needed or not, and links with it if needed.

In any case, if you do a patch against liblo, don't forget to submit it
upstream.

Thanks!

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
http://bootlin.com