I have an MBR style formatted SD card where I need a PARTUUID in order to mount a partition there as the rootfs (via linux kernel parameter
root=PARTUUID=...). Using an fs UUID does not work.
blkid does not show any PARTUUIDs, only UUIDs.
I understand that PARTUUID is not a historical feature of MBRs, but that they can still be used. I have looked around for a way to add or change a PARTUUID, but all I can find is stuff where a GPT is being used.
I've seen various ways to extract an existing uuid but the identifier I get is always just four null bytes (i.e., all zeros). This is also what
fdisk gives as the "Disk Identifier",