Partition type of USB live image is now "empty"

Alexander Thomas alexander.thomas at
Wed Jan 27 18:25:01 CET 2021

In older FAI versions, the partition containing the live image would
be given a type “cd” (that's actually 0xCD because it seems there is
no appropriate partition type for ISO 9660 images).
The current version sets the type to 0, which means “empty”. This is
problematic when using for instance Windows to add an extra partition
to a USB stick that has the FAI installer dd'ed to it. Windows will
treat the “empty” partition as true empty space and discards the
partition entry entirely when writing the new table. The result is
that the USB stick becomes unbootable because dracut can no longer
find the live partition, it instead tries to boot from the EFI
partition which results in:

mount: /run/initramfs/live: unknown filesystem type 'vfat'
dracut: FATAL: Failed to mount block device of live image
dracut: Refusing to continue

Was there any specific reason to drop the ‘cd’ partition type? This
was obviously a wrong type, but at least it prevented disk utilities
from throwing it away.  fdisk seems to agree:
“Type 0 means free space to many systems. Having partitions of type 0
is probably unwise.”


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