[OE-core] Generating UBIs containing multiple volumes

[Jon Szymaniak]

Hi all,

I see that the image_types.bbclass's IMAGE_CMD_ubi() does the following:
  1) Creates a single-volume ubinize.cfg on the fly
  2) Runs mkfs.ubifs to create the UBIFS image
  3) Run ubinize to create a UBI image

However, I'm currently using a two-volume image: one volume for the
rootfs, and one for "user config" as shown in the below ubinize.cfg.
I'm considering making some changes to image_types.bbclass to support
this and was hoping I could get some feedback and advice.

[rootfs]
mode=ubi
image=rootfs.ubifs
vol_id=0
vol_size=200MiB
vol_type=dynamic
vol_flags=autoresize
vol_name=rootfs

[config]
mode=ubi
image=config.ubifs
vol_id=1
vol_size=8MiB
vol_type=dynamic
vol_name=config

I'd planned to stage my config.ubifs with some sane default files via
a recipe (e.g., an ubinize invocation in a do_compile). It feels like
it might be "bad practice" to have a recipe install config.ubifs
(perhaps a name with a timestamp and then a shorthand symlink, as done
with existing image files) into $(DEPLOY_DIR_IMAGE}. Any
recommendations?

Where would be an appropriate place to keep a custom ubinize.cfg? In
my case, it should always remain the same for my MACHINE. However, I'm
not certain if this would be always be the case for other folks...

Thank you,
Jon