[oe] [Bitbake-dev] A new bitbake extension: .bbappend files

[Richard Purdie]

On Fri, 2010-07-16 at 15:25 +0100, Richard Purdie wrote:
> Whilst our layers mechanism, is great it does have a drawback which has
> bugged me for a while. If you have a recipe like pointercal which has
> machine specific information in it and you have your new machine code in
> a layer, how do you add a pointercal file for your machine?
> 
> Answer is you copy the whole pointercal recipe and files into your
> layer, then add the single file for your machine. To me this is ugly,
> ugly, ugly. We hate code duplication and as soon as you create two
> copies of the same information, we've failed.
> 
> So how could we do this better? Somehow we need to say that a given
> directory X has some information which should be merged with the
> original recipe. I've thought through several different ways of doing
> this and the best solution I found was "bbappend".
> 
> The idea is that if bitbake finds any X.bbappend files, when it loads
> X.bb, it will also include these files after it parses the base .bb file
> (but before finalise and the anonymous methods run). This means that
> the .bbappend file can poke around and do whatever it might want to the
> recipe to customise it.
> 
> I went ahead and tried it out as its quite simple to code this in
> bitbake. I liked the result enough I've already merged this into Poky:
> 
> http://git.pokylinux.org/cgit.cgi/poky/commit/?id=63e6ba85677b8aa9f4cf9942a1fccbb8a8c72660
> 
> I'm proposing to push it to bitbake master if there are no serious
> objections.

Whilst I think there were some initial concerns the consensus seemed to
be that this was a good thing to have in bitbake, its something that has
been on the feature wishlist since day one so I've merged the patch into
bitbake master.

Cheers,

Richard