make installkernel boot/device.hints error

[Peter Risdon]

Freshly cvsupped two machines, one built and installed world/kernel 
fine, the second builds world and kernel OK then gives the following 
error for make installkernel:

su-2.05b# make installkernel
cd /usr/obj/usr/src/sys/GENERIC;  MAKEOBJDIRPREFIX=/usr/obj 
MACHINE_ARCH=i386  MACHINE=i386  CPUTYPE= 
GROFF_BIN_PATH=/usr/obj/usr/src/i386/legacy/usr/bin 
GROFF_FONT_PATH=/usr/obj/usr/src/i386/legacy/usr/share/groff_font 
GROFF_TMAC_PATH=/usr/obj/usr/src/i386/legacy/usr/share/tmac 
PATH=/usr/obj/usr/src/i386/legacy/usr/sbin:/usr/obj/usr/src/i386/legacy/usr/bin:/usr/obj/usr/src/i386/legacy/usr/games:/usr/obj/usr/src/i386/usr/sbin:/usr/obj/usr/src/i386/usr/bin:/usr/obj/usr/src/i386/usr/games:/sbin:/bin:/usr/sbin:/usr/bin 
  /usr/obj/usr/src/make.i386/make KERNEL=kernel install
You must set up a /boot/device.hints file first.
*** Error code 1

Stop in /usr/obj/usr/src/sys/GENERIC.
*** Error code 1

It seems pretty self-explanatory, but I've never encountered this 
before, so have two questions:

  - Would it be OK just to copy a device.hints file into /boot from 
another machine?

  - Could anyone give me a steer on understanding why this happened?

TIA

Peter.