<div dir="ltr"><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Jan 22, 2014 at 6:16 PM, Khem Raj <span dir="ltr"><<a href="mailto:raj.khem@gmail.com" target="_blank">raj.khem@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="im">On Friday, December 06, 2013 05:42:26 PM Khem Raj wrote:<br>
> ??= does not react at all with<br>
> BOOST_LIBS += "${@base_contains('PACKAGECONFIG', 'python', 'python', '',<br>
> d)}"<br>
><br>
> even though we have<br>
><br>
> PACKAGECONFIG ??= "" it does not honor it and always add python to<br>
> BOOST_LIBS but the dependency is not added so it fails to build<br>
> complaining for missing python headers which is a understood outcome<br>
><br>
> When converted to ?= it works as expected and only add --with-python<br>
> in bjam when python is specified in PACKAGECONFIG otherwise not.<br>
><br>
> Is it a bitbake bug ? in anycase ?= should be enough of loose rope<br>
> to let user/distro configure the packageconfig policy<br>
><br>
<br>
</div>OK so the problem is that I have meta-ros in my layer-mix and in that layer<br>
it defines PACKAGECONFIG ?= "python" IMO it should have appended instead of<br>
redefining. Thats why I was seeing what I was seeing.</blockquote></div><br>It's worth noting that recipes, in general, should use ?= rather than ??=, but config files, in general, should use ??=. Otherwise it becomes impossible for the config metadata to define an overriding default -- the last ??= wins, after all, and that would always be the recipe. IMO default values in the recipe are there to give sane behavior when there's no configuration coming in from elsewhere, not to override configuration defaults.<br>
-- <br>Christopher Larson<br>clarson at kergoth dot com<br>Founder - BitBake, OpenEmbedded, OpenZaurus<br>Maintainer - Tslib<br>Senior Software Engineer, Mentor Graphics
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