Modify a yocto images `/data/` partition before flashing

I would like to manually modify the content of the /data partition from a generated yocto image. I mounted the partition using the block offset, changed some data there, compressed and flashed the image with bmaptool. Unfortunately, this changes a checksum which bmaptool complains about.

Is there a tool such as mender-artifact that allows to modify that partition?

EDIT: I just gave it a try to run bmaptool create on the (uncompressed) image. The generated .bmap file contains just a single line in <BlockMap> whereas the original hat around 15 entries. So, I guess this does not work just like that?

EDIT: I successfully flashed the image and booted the device. Also file system expansion of the /data partition works as expected. Are there things that can go wrong with regard to future updates this way or do I just have to live with the reduced writing efficiency because of that single <BlackMap> entry?

Hi @HerrMuellerluedensch

Have you had a look at the mender-artifact tool?

The cat, cp, modify commands should be able to work with SD images and the data partition at least.