[OE-core] [PATCH v2 1/1] classes/whitelist: add class to allow whitelisting recipes from a layer

[Paul Eggleton]

On Friday 28 August 2015 09:34:18 Paul Eggleton wrote:
> On Thursday 27 August 2015 23:07:44 Khem Raj wrote:
> > > On Aug 27, 2015, at 5:36 AM, Paul Eggleton
> > > <paul.eggleton at linux.intel.com>
> > > wrote:
> > > 
> > > Allow restricting recipes brought from a layer to a specified list. This
> > > is similar in operation to blacklist.bbclass, but instead specifies a
> > > per-layer whitelist of recipes (matched by PN or BPN) that are able to
> > > be built from the layer - anything else is skipped. This is potentially
> > > useful where you want to bring in a select set of recipes from a larger
> > > layer e.g. meta-oe.
> > 
> > For the record, I am not in favor of such feature in OE, Distros can still
> > use BBMASK if they wish to
> 
> This is significantly easier to use than BBMASK though. (Perhaps that's why
> you don't like it?)

I should expand upon this with a couple of important distinctions:

* BBMASK is a list of files to mask out, so it's a blacklist not a whitelist. 
(Sure, you could probably construct a regex that effectively gives you a 
whitelist; it probably won't be pretty though.)

* BBMASK tells bitbake not to even try reading the masked files, which means if 
you then request to build any of them (either directly or via a dependency) 
you'll be told that there's nothing providing that with no explanation as to 
why. With whitelist.bbclass (and blacklist.bbclass, which whitelist.bbclass is 
modelled after) we are using SkipPackage/SkipRecipe so you at least get a 
statement that the recipe was skipped as well as hopefully an explanatory 
reason as to why.

Cheers,
Paul

-- 

Paul Eggleton
Intel Open Source Technology Centre