Cross compile world on i386 to x86_64

[Michael Weiser]

Hello,

my trusty P-III died on me last week and I've bought an Athlon 64
replacement. I'm quite sure I'll get my installed FreeBSD-CURRENT to run
on it in 32bit mode (i386). But to fully exploit the architecture I'd
like to run it in 64bit mode (amd64). Now I'm wondering:

Can I avoid reinstalling the system with amd64 binaries by
cross-compiling world and kernel for amd64 on the installed i386 FreeBSD-CURRENT?

I'm thinking like this:

- make buildkernel ARCH=amd64 (or the like)
- make installkernel
- boot the 64bit kernel with the old 32bit userland
- make buildworld
- make installworld
- mergemaster

I'm not sure:

- how to get a compiler that can produce an amd64 kernel with make
  buildkernel
- if the 32bit userland will run on a 64bit kernel
- if make buildworld for amd64 will work with a 32bit userland

Is something like this supposed to work? Has anyone done it?

Thanks in advance.
-- 
bye, Micha
Don't panic!