On Wednesday 28 November 2012 08:45:15 Robert P. J. Day wrote:
> On Wed, 28 Nov 2012, Paul Eggleton wrote:
>
> ... snip for brevity...
>
> > So the bit that might be missing here is that the PACKAGE_GROUP
> > structure and the packagegroup recipes/class are actually not really
> > related, except that the latter may be used to populate the former.
> > "packagegroup" is the new name for what used to be known as a "task"
> > in versions before danny and much better reflects what these recipes
> > do. PACKAGE_GROUP_* actually came first as a way to define items for
> > IMAGE_FEATURES that map to one or more packages, and I'm not sure
> > the name choice was a particularly good one - I wonder if it would
> > be worth considering renaming it to something like
> > IMAGE_FEATURE_PACKAGES in order to avoid confusion, although
> > obviously every rename like this has a cost associated.
> >
> > In any case, I would definitely recommend using the term "package
> > group" to refer to packagegroup recipes only, otherwise you're only
> > likely to increase people's level of confusion.
>
> one more observation just to mess things up a bit more -- the fact
> that, despite what one reads in core-image.bbclass, the IMAGE_FEATURES
> variable can be used to customize your image in ways that have nothing
> to do with packages or package groups.
>
> witness this from meta/classes/rootfs_ipk.bbclass:
>
> if ${@base_contains("IMAGE_FEATURES", "read-only-rootfs", "true",
> "false" ,d)}; then if grep Status:.install.ok.unpacked ${STATUS}; then echo
> "Some packages could not be configured offline and rootfs is read-only."
> exit 1
> fi
> fi
>
> so there's a potential "image feature" called "read-only-rootfs" which
> is clearly not a package group or a package, and of which there is no
> mention in core-image.bbclass.
Yep, that's intended - there are a number of these. IMAGE_FEATURES controls
features in the image, whether they are sets of packages to be installed or
other aspects to enable during image construction.
This particular IMAGE_FEATURES item (read-only-rootfs) is not listed probably
because it's limited to the ipk backend only and not widely used. There is a
bug open to implement it for rpm and deb, at which time it should probably be
added to the list there and to the one in the manual.
Cheers,
Paul
--
Paul Eggleton
Intel Open Source Technology Centre
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