Can DFly root from a hammered-slice?

[Bramble Whisper]

Hi all:
 I sliced my hard drive into ad4s1 and ad4s2, then disklable the
former and create ufs on ad4s1a and hammer on ad4s2
 The ad4s1a is mounted as /boot and ad4s2 as /, /usr and other staff
are nullfsed to /pfs/...
 Then I edit the /boot/loader.conf with
vfs.root.mountfrom="hammer:ad4s2" just as the rcconfig said.
 However, when I boot the box, it reports no disklabel and cannot boot.
 So, can DFly root from a slice not disklabel?

 Well, I know the disklabel is better, it is a mistake but I cannot
bear a repartition now :(
 BTW, do we still need disklabel if we got gpt and hammer?

best wishes
whisper :)