I found myself needing to downgrade a system with 8-CURRENT to 7-STABLE. It was almost painless but I’d like to outline the procedure that worked for me:
* Get the right version of the sources with cvsup
* Build the kernel, boot it with reboot -k
* Make buildworld
* Make kernel
* Edit /usr/src/Makefile to add /rescue in front of the PATH so the utilities requiring FBSD_1.1 (hey! what’s with the “cp” utility requiring FBSD_1.1??) don’t get used
* Make installworld
* Mergemaster, etc. as needed
I didn’t have any ports on the machine; If I had I’d rm everything from /usr/local or rebuilt them.
This will probably work less and less reliably as 8-CURRENT diverges from 7-STABLE.