Cross platform building best practices (building 6 on 7)

[Alexander Sack]

Hello Folks:

I've done a lot of Googling and scouring the lists about this
particular subject so I apologize for rehashing it.  However, I'm
still confused on what's the best way to perform BSD cross platform
builds.  Ideally what I want to have is an environment whereby I can
build a 6.1-RELEASE tree on a 7.0-RELEASE box.  I thought originally I
could check out a 6.1 release version, perform make world, and then
use the output of that build as either a basis for a jail or a
toolchain.  However, as noted by previous threads, 6.x doesn't build
on a 7.x due to gcc4/binutils compatibility issues (please correct me
if I'm wrong).  I then thought I could potentially download a patched
binutils, copy it into src/contrib/binutils and that would potentially
fix it.  No dice (and I'm still debugging why since this binutils
package DOES build outside of the make world infrastructure without
issue, this very well could be pilot error on my part since I didn't
update the VERSION string and didn't trim the source files as per the
FreeBSD-deleteList etc.).

I THEN thought if I build/install a gcc-3.x/bintuils toolchain I could
complie a 6.x on a 7.x machine.  Well I haven't done that yet since at
this point I believe I'm diverged from the path of FreeBSD build
enlightenment!  Moreover, if would be NICE if I could bootstrap the
normal dev tools from the exiting make world build tree.  I'm not yet
ready for a lot of hackery on the build tree without asking around.
:D!

Does anyone due cross-platform builds (without host virtualization)?

Thanks!

-aps