[Openembedded-architecture] Layer compatibility markup proposal

[Richard Purdie]

Hopefully this is a simple and uncontroversial idea :)

I'd like to be able to set something like this in OE-Core's layer.conf
file:

LAYERSERIES_CORENAMES = "rocko"

and then layers would set something like:

LAYERSERIES_COMPAT = "rocko"

It would become a hard requirement for Yocto Project Compatibility v2
to have this set.

If a layer sets _COMPAT but doesn't have an overlapping namespace, it
would error.

We'd suggest layers use the next as yet unreleased codename by default
so that when OE-Core releases, things "ripple" through the system with
minimal disruption as people release from master to stable branches at
a staggered rate. I had toyed with a "master" keywork too but I think
that works against us.

I'd would be possible for a layer to be marked as compatible with
multiple release series, at the maintainers discretion.

In case its not clear, the intent here is so that someone trying a
master branch of some unmaintained layer gets a clear error about
whether its compatible or not. Obviously someone can easily tweak the
layer to remove the error but it would stop a very common new user
experience issue we have.

I guess a slightly more controversial idea would be backporting this to
some of the stable releases? :)

Any thoughts on this?

[I've been thinking about this for a while but finally wrote the idea
down]

Cheers,

Richard