*.ko.symbols files in /boot/kernel

[Sergey Kovalev]

I've decided to upgrade from 6.4-p1 to 7.1-RC2 on my home desktop pc.
Somewhat during this procedure triggered building and installing of 
*.ko.symbols and kernel.symbols files.
Here are my upgrade commands
cd /usr/src
env -i make buildworld
env -i make buildkernel KERNCONF=KOCA
env -i make installkernel KERNCONF=KOCA

After that I get errors because my / patrition is only 128M in size. And 
/boot/kernel gets filled with *.symbols files.
What could trigger their building and installation?

And how I should cleanly rebuild/reinstall kernel in this case without 
rebuilding the world. I know the right path to rebuild everything 
cleanly, but never faced such difficulties.

My /etc/make.conf: http://kovalev.com.ru/make.conf
My kernel config: http://kovalev.com.ru/KOCA

Please CC me cause I'm subscribed to the list.

PS I've mistyped address and first posted to freebsd-users at freebsd.org. 
Sorry if I posted to the same list twice.