Converting i386 to amd64

[Michael Powell]

Greetings everyone:

This is probably a pretty dumb question, but it's never really come up for 
me before. I am at a crossroads with regard to some hardware upgrades, and 
for a couple of them I have been putting off making the change to 64 bit. 
These are server boxen with no concerns for desktop use.

Is it possible to change an i386 install to amd64 without needing to start 
from scratch? I was poking around reading some stuff, and ran across this in 
in /usr/src/Makefile:

# If TARGET=machine (e.g. ia64, sparc64, ...) is specified you can
# cross build world for other machine types using the buildworld target,
# and once the world is built you can cross build a kernel using the
# buildkernel target.

Does this mean I can achieve the desired effect with "make buildworld 
TARGET=amd64", et al? It would be a tremendous time-saver for me.

Of course I would follow with a portupgrade -fa and rebuild all ports 
afterward.

Thanks in advance for the wielding of any clue sticks.  :-)

-Mike