As far as I know there is no particular advantage to having it in the eMMC. And because of Mender’s special boot code, it is tightly coupled to the rootfs partition configuration in the main storage, so it makes sense that it’s next to it.
The advantage to putting it in the boot partitions of the eMMC is that these are typically implemented in pSLC within the flash which is more reliable and they typically have write protection to protect them from corruption. This would be a good option to have but it sounds like we should stick to the tested path for now. To be clear here, this all lives within the eMMC, the boot partition is just a special area in the eMMC that is more reliable and has special protections on it.
Thanks for the rest of the clarifications on the variables. We will take a deeper look into what is required for this later on.
Only that you need to use Mender client 2.2.1 or later, as previous versions are not compatible with libubootenv. Otherwise libubootenv is perfectly compatible with uboot-fw-utils as far as I know.
We will give this a try today. I will update on the other issue I posted for any further issues with this integration.