[oe] the awkwardness of using core-image.bbclass

[Robert P. J. Day]

On Fri, 11 Jul 2014, Rudolf Streif wrote:

> Hi Robert,
>
>
>
> >   some observations/questions on core-image.bbclass, and whether it
> > can be used more understandably. this is being written from the
> > perspective of someone who has had the occasional student ask, "why
> > was it done *that* way?"
> >
> >   so here's the important part of core-image.bbclass:
> >
> > CORE_IMAGE_BASE_INSTALL = '\
> >     packagegroup-core-boot \
> >     packagegroup-base-extended \
> >     \
> >     ${CORE_IMAGE_EXTRA_INSTALL} \
> >     '
> >
> > CORE_IMAGE_EXTRA_INSTALL ?= ""
> >
> > IMAGE_INSTALL ?= "${CORE_IMAGE_BASE_INSTALL}"
> >
> > inherit image
> >
> >   whose job is obviously to define the final contents in IMAGE_INSTALL
> > to be handed off to image.bbclass. so far, so good. but notice first
> > that while IMAGE_INSTALL and CORE_IMAGE_EXTRA_INSTALL are weakly
> > assigned, CORE_IMAGE_BASE_INSTALL is *not*, which -- if one is
> > perusing that file -- strongly suggests that if you're inheriting
> > from this class file, you really should use that value. but it doesn't
> > work that way.
> >
> > Consider CORE_IMAGE_BASE_INSTALL as a default value for IMAGE_INSTALL.
> It's internal to the core-image class only. Hence, it makes sense for it to
> be directly assigned. It is not meant to be used by any other classes or
> recipes. With the default value the most simple recipe you can write to use
> the core-image class is:
>
> myimage.bb:
>    inherit core-image
>
> which will produce an image that boots to the console and include
> hardware support if so defined by machine and distro features.
>
> IMAGE_INSTALL and CORE_IMAGE_EXTRA_INSTALL are meant to be
> overwritten by image recipes and configuration files.

  i know, which is exactly what is so counter-intuitive with the way
the above is done. you can override those two variables, but not
CORE_IMAGE_BASE_INSTALL directly, it just seems silly.

rday

-- 

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Robert P. J. Day                                 Ottawa, Ontario, CANADA
                        http://crashcourse.ca

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