[yocto] of recipes and packages

[Jeff Osier-Mixon]

I tend to think of packages as "ingredients", in keeping with the
cooking metaphor. They have version numbers, just as ingredients in
the refrigerator have expiration dates. The recipes, however, have
their own version numbers, but they are less critical to the success
of the build - maybe my Aunt Agnes has a version of Betty Crocker's
yellow cake recipe, but improved slightly. If I make that recipe with
old eggs, though, it will fail.

In this case, bitbake is looking for the expiration dates on your
ingredients - the version of the package that each recipe builds. With
the list that comes from bitbake -s you can determine whether any of
your packages is the right one.

As for the versions of the recipes themselves, the Yocto Project's QA
and testing process makes sure that each of the included recipes
works, in the sense that it builds the package reliably. You can spice
them up if you like.

Chris Hallinan wrote up a good description of many of the terms used
in the project:
http://blogs.mentor.com/chrishallinan/blog/2012/04/13/yocto-versus-poky-versus-angstrom-etc/

Hope that helps

On Wed, Aug 22, 2012 at 10:05 AM, Trevor Woerner <twoerner at gmail.com> wrote:
> Okay, if the confusion over "yocto" versus "yocto project" versus
> "poky" and trying to decide whether poky or yocto is a distribution or
> a build system or sometimes both or neither of either wasn't bad
> enough... there now comes a new confusion:
>
> recipes versus packages
>
> an image is composed of packages
> a recipe for a given piece of software generates a set of packages
>
> to discover the list of packages generated by a recipe one can use:
> $ bitbake -e <recipe> | grep "^PACKAGES="
>
> to discover the list of available recipes (for a given set of layers)
> one can use:
> $ bitbake -s
>
> However:
>
> $ bitbake --help | grep -- -s
> ...
>   -s, --show-versions   show current and preferred versions of all packages
> ...
>
> "...versions of all _packages_"!? Shouldn't that be "recipes"?
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-- 
Jeff Osier-Mixon http://jefro.net/blog
Yocto Project Community Manager @Intel http://yoctoproject.org