Ick.  Replying to myself.

| I have also found problems with the cross-generated boot
| blocks.  I don't know how far it extends, but I know that
| load-file-print-size, is corrupt.  The source is:

I have fixed fgen and the resulting bootblock is quite 
happily reading 16K/2K filesystems from recent autobuild
snapshots.  Hopefully this will solve the issue for you
too.

Eduardo