* support empty /etc boots nicely:
- nspawn/gpt-generator: introduce new gpt partition type for /usr
+ - nspawn: add --mode=auto,stateful,stateless,volatile
+ - fstab-generator: support auot/stateful/stateless/volatile on the kernel cmdline, too
+ - fstab-generator: add support for usr= in addition to root= on the kernel cmdline
* generator that automatically discovers btrfs subvolumes, identifies their purpose based on some xattr on them.