On 23 May 2017 at 15:31, H. Nikolaus Schaller <hns@goldelico.com> wrote:

U-Boot only has some support for partition UUIDs.

I know it can also determine filesystem UUIDs, since Robert Nelson's images use these for booting the system (provided an initramfs is present, since the kernel doesn't support them)

I am not sure if the "MLO in FAT partition" approach works for GPT at all.

Not afaik. Of course when MLO at fixed offset is used you can use any partition table format you want, but I don't know if older SoCs support this.

By the way: this UUID thing is a strong argument against creating SD cards
by dd-ing some .img to the raw disk. They will all share the UUIDs and are not
uniquely identified any more.

Yes it's recommended to randomize various ids after flashing:

- disklabel (maybe, if you care)

- filesystem uuid

- machine id

- ssh host keys

I generally use a script which does all that after dd'ing the image and expanding it to fit using resize2fs.

I also try to avoid using UUIDs anywhere in the first place.

Matthijs