[oe] [RFC] turning conf/machine into a set of bblayers

[Richard Purdie]

On Thu, 2010-10-21 at 11:59 +0200, Koen Kooi wrote:
> The downside of amend.inc is the de-sync when the recipe gets updated,
> but not the overlay. You run the risk of using a version without the
> overrides that way.
> Maybe some fancy scripts, (pre-)commit hooks or just old fanishioned
> review on the ml could solve those type of issues.
> 
> How do file overrides like
> recipes/netbase/netbase/beagleboard/interfaces get handled in a
> bblayer/amend.inc world?

Taking a poky example of formfactor which is a very similar situation,
create a .bbappend file:

http://git.pokylinux.org/cgit/cgit.cgi/poky/tree/meta-emenlow/packages/formfactor/formfactor_0.0.bbappend

with the contents of:

FILESEXTRAPATHS := "${THISDIR}/${PN}"
PRINC = "1"

and place the appropriate files underneath as usual:

http://git.pokylinux.org/cgit/cgit.cgi/poky/tree/meta-emenlow/packages/formfactor/formfactor/emenlow/machconfig

We should make it a hard fail if a .bbappend is found with no
corresponding .bb file, I'm not sure if that happens or not at the
moment.

I've also been thinking a lot about FILESPATH and have been thinking
that making the list of defaults small and having recipes specify if
they use overrides would be a good idea.

E.g. so above you'd have to specify:

"${THISDIR}/${PN}/${MACHINE}" explicitly.

Cheers,

Richard