[OE-core] Overriding a variable only in our layer

[Richard Purdie]

On Wed, 2011-11-23 at 01:24 +0000, Daniel Lazzari wrote:
> I ran into an interesting problem today that I need some help with.
> I’m not sure if this is a bitbake issue or an oe-core one so I thought
> I’d try here first. We have our own layer that overlays on top of
> oe-core, meta-oe, and meta-angstrom. Our layer has a bunch of recipes
> that pull projects from our local SVN, including a recipe for u-boot.
> We have a build configuration file that has lines like the following:
>
> SRCREV_pn-u-boot = “563”
>  
> We pull in this conf at build time using bitbake’s –R argument. Just
> recently we switched u-boot’s SRCREV from ${AUTOREV} to an actual
> revision number and bitbake started choking trying to parse recipes.
> It looks like it chokes while trying to parse oe-core’s u-boot git
> recipe because the SRCREV is meant for SVN, not GIT (even though our
> PREFERRED_VERSION is set up only to build our u-boot). Is there a way
> to override this SRCREV variable only when parsing recipes in our
> layer? I know I can do it directly in the recipe, but that loses us
> the advantages of having all of the SRCREVs in one file (which makes
> specific full rebuilds very easy).

We've not seen a conflict like that before. I'd suggest two possible
solutions off the top of my head:

a) Rename your svn recipe to something like "u-boot-svn" so its clear
which recipe the revision is meant for

b) .bbappend the .git recipe and force bitbake to ignore it (variables
like COMPATIBLE_HOST/COMPATIBLE_MACHINE/BROKEN spring to mind). I do
wonder if these mechanisms trigger early enough to stop bitbake choking.
If not, you could set SRCREV_pn-u-boot in the .bbappend to something it
won't choke on for the git recipe only. Not brilliant but should let you
maintain your existing file.

Cheers,

Richard