[OE-core] Contents of non-rootfs partitions

[Kristian Amlie]

Hey

In Mender we are using a dual rootfs partition layout (A/B layout) with a persistent data partition on the side. We're using wic to do the actual image building.

However, putting files into this data partition is not a straightforward operation ATM. All recipes in OE put files into the rootfs only, and we'd like there to be a way to specify that files should go into the data partition.

I haven't seen any straightforward way to do this in OE. Some suggestions for how it could be done:

* A "DATA_FILES" variable (like "IMAGE_BOOT_FILES"), where you can list files you'd like to be included. This is very straightforward, but has the disadvantage of being a bit hairy when paths are involved, and it doesn't allow for much logic.

* Keep a special "data" directory, something similar to sysroot, where recipes could install files into in order to have it included on the data partition. We could potentially have a bbclass for use in recipes to make this more streamlined.

* Have a special recipe that users can bbappend, which specifically install to the data partition (this might also need a "data" directory, like above).

It's also possible that this should be generalized further so that it doesn't only apply to a data partition, but to any non-rootfs partition.

I'm willing to invest some time in this, but I thought I'd gather some opinions first.

Thoughts?

-- 
Kristian