[yocto] How does RRECOMMENDS work?

[Paul Eggleton]

Hi Chris,

On Monday 08 September 2014 08:55:15 Chris Tapp wrote:
> I've got a recipe to which I've added:
> 
> RRECOMMENDS_${PN} = "<package>"
> 
> The documentation says that "If, during the build, a package from the
> RRECOMMENDS list cannot be found, the build process continues without an
> error".
>
> I tried a build without <package> (i.e. no recipe) and it failed with
> "Nothing provides <package>". Is this the expected behaviour? If so, is
> there a way I can pull in a package if it is build-able and skip it
> otherwise?
> 
> In this case <package> contains some utilities which can be of help, but
> they're not required in any way at runtime.

Scott has just pinged me about this, the manual is slightly misleading. How it 
works is, if you have an item mentioned in RRECOMMENDS, there must be a recipe 
that provides that item via RPROVIDES (or indirectly via PACKAGES or 
PACKAGES_DYNAMIC), otherwise you will receive the error you mentioned. 
However, if the package does not actually end up being produced, that is OK.

RRECOMMENDS is generally for things that you normally would expect to be 
available, but may not be for some reason (e.g. kernel modules that might 
instead be compiled in and thus are not produced as a package).

Cheers,
Paul

-- 

Paul Eggleton
Intel Open Source Technology Centre