The case for the /usr merge

> Encrypted root filesystems, for one thing.

Yes. Another reason are special requirements for the boot loader itself.

For instance, I'm using ReiserFS for /. This FS employs "tail packing", i. e. there are cases when file data will be stored in units smaller than a full cluster ("sector").

File-system agnostic boot-loaders like LILO assume that all sectors in a block list have the same size, and therefore require ReiserFS volumes to be mounted with a special option which disables tail packing when updating the LILO configuration/mapping files.

But mounting ReiserFS with this option defeats its main advantage of space-efficiency for small files, so one does not generally want to do that.

As long as /boot is a separate small file system, this does not matter: One can either use ReiserFS for /boot and mount it with tail packing disabled, or use a different FS like ext2 there which only uses equally-sized clusters (this is what I do).

Also, the current FHS does not force anyone to put /boot onto a different partition - it's just an option.

Therefore, no matter where the basic discussion /bin vs. /usr/bin will eventually lead to, I strongly advise *not* to change the existing practice regarding /boot.