[OE-core] what is "packagegroup-core-nfs-server"?

[Paul Eggleton]

On Wednesday 28 November 2012 08:14:44 Robert P. J. Day wrote:
> On Wed, 28 Nov 2012, Martin Jansa wrote:
> > On Wed, Nov 28, 2012 at 07:58:45AM -0500, Robert P. J. Day wrote:
> > > On Tue, 27 Nov 2012, Saul Wold wrote:
> > > > On 11/27/2012 08:18 PM, Robert P. J. Day wrote:
> > > > >    poking around core-image.bbclass, and noticed this:
> > > > > PACKAGE_GROUP_nfs-server = "packagegroup-core-nfs-server"
> > > > > 
> > > > > except i don't see the corresponding packagegroup-core-nfs-server.bb
> > > > > recipe file.  there *is* a packagegroup-core-nfs.bb file; how is the
> > > > > above processed?
> > > > 
> > > > It's defined in recipes-core/packagegroups/packagegroup-core-nfs.bb
> > > > 
> > > > The line
> > > > PACKAGES = "${PN}-server"
> > > > provides the key you are looking for.
> > > > 
> > >   a followup, for which i'm quite prepared to embarrass myself --
> > > 
> > > where is the "splash" package group defined?  i can see this in
> > > image.bbclass:
> > > 
> > > SPLASH ?= "psplash"
> > > PACKAGE_GROUP_splash = "${SPLASH}"
> > > 
> > > and numerous images add that "splash" package group.  but my first
> > > impression was that any package would be defined under some
> > > "packagegroups/" directory, and would necessarily need to "inherit
> > > packagegroup".
> > > 
> > >   so what am i missing?
> > 
> > PACKAGE_GROUP_foo can be provided by any recipe, not only
> > packagegroup-*
> 
>   ok, that's useful information that doesn't seem to be documented
> anywhere (or is it?).
> 
>   however, if a regular recipe can be used as the basis for a package
> group, would it not still have to contain "inherit packagegroup" to be
> defined as a package group?  or can any regular recipe act as its own
> package group?  i examined the "psplash" recipe and i saw nothing that
> suggested it was available as a package group.
> 
>   i realize these are nitpicky questions but it's the sort of thing
> someone's guaranteed to ask me at some point, so i want to nail it
> down.

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.

Cheers,
Paul

-- 

Paul Eggleton
Intel Open Source Technology Centre