If you are building on an older system (like 1.5.x) you should read
/usr/src/UPDATING. If not, please give more detailed information (what
system you are building on, what branch you used when cvs update'ing)

Basically you will need to do

  cd /usr/src
  ./build.sh -t -T /usr/tools

and then use /usr/tools/bin/nbconfig and /usr/tools/bin/nbmake to create
the new kernel.


Martin