coreboot systems are not supported: FSUUID is unset

I don't know if this affects all coreboot systems or only some, but we receive quite a few "Resizing system partition failed" reports, because our 1st boot partitioning hook can't do its job: $FSUUID is unset, probably because the boot medium is an ISO, and not a USB image. Skipping partitioning. So automatic upgrades and creating Persistent Storage won't work.

It seems we might need to ship a GRUB compiled for coreboot to solve that.

For now I'm recording this as a known issue and "great patches welcome". We'll see if we ever want, and can afford, to prioritize this any higher.

Whisperback identification

• Look at /proc/cmdline: FSUUID is empty or absent.
• proof: lines like amnesia kernel: ACPI: XSDT 0x000000007FAB10E0 00005C (v01 CORE COREBOOT 00000000 CORE 00000000)
• this is not relevant: /sys/bus/coreboot