<div dir="ltr"><br><div class="gmail_extra"><br><br><div class="gmail_quote">On Wed, May 22, 2013 at 3:14 AM, Phil Blundell <span dir="ltr"><<a href="mailto:pb@pbcl.net" target="_blank">pb@pbcl.net</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 Wed, 2013-05-22 at 09:47 +0100, Paul Barker wrote:<br>
> I've just sent a patch to the yocto@ list to fix this but it's brought<br>
> up two things:<br>
><br>
> 1) In openembedded-core/meta/classes/image.bbclass SPLASH is set with<br>
> '?='. I'm overriding this with '=' in<br>
> meta-raspberrypi/conf/machine/raspberrypi.conf which means it can't be<br>
> overridden further in local.conf. Is this worth changing to '??=' in<br>
> image.bbclass, '?=' in the machine conf so that it can be overridden<br>
> with '=' in local.conf? Is my understanding of the overrides correct<br>
> here?<br>
<br>
</div>You can always override it from local.conf using a _forcevariable<br>
override (which used to be named "_local", in fact, but that terminology<br>
turned out to be a bit confusing), or a _MACHINE override of course. So<br>
I don't think there is any major problem here.<br>
<br>
But, that said, it probably is true that the semantics of ??= are less<br>
surprising for users (since it isn't position-dependent in the way<br>
that ?= is) which might make it a better choice for image.bbclass.</blockquote><div><br></div><div style>??= is great in config files, but not ideal in classes that aren't globally inherited. If bitbake.conf sets a ??=, and a distro .conf updates the default by using ??= again, and then the class uses ??=, it'll replace the latest default set by the config. So, I think for default values, classes should use ?=, config files should use ??=.</div>
</div>-- <br>Christopher Larson<br>clarson at kergoth dot com<br>Founder - BitBake, OpenEmbedded, OpenZaurus<br>Maintainer - Tslib<br>Senior Software Engineer, Mentor Graphics
</div></div>