Some support tools are required before you can build the kernel. These are the compilation instructions for building them:

% cd ~/src/Libstreams-23
% make install DSTROOT=/tmp/Libstreams.dst
% (cd /tmp/Libstreams.dst; sudo pax -rw . /)

% cd ~/src/bootstrap_cmds-44
% make install DSTROOT=/tmp/bootstrap_cmds.dst
% (cd /tmp/bootstrap_cmds.dst; sudo pax -rw . /)

% cd ~/src/cctools-495.8
% make install_tools DSTROOT=/tmp/cctools.dst SUBDIRS="libstuff libmacho misc" RC_OS=macos
% (cd /tmp/cctools.dst ; sudo pax -rw . /)
% make lib_ofiles_install DSTROOT=/tmp/cctools.dst SUBDIRS="ld" RC_OS=macos
% (cd /tmp/cctools.dst ; sudo pax -rw . /)

The following step can only be done on Mac OS X, as Darwin (and as such OpenDarwin) lacks xcodebuild. For those people building xnu on Darwin/OpenDarwin a fat binary for i386 and ppc of kextsymboltool can be found here. The kextsymboltool is assumed to be in /usr/local/bin.

% cd ~/src/kext_tools-42
% xcodebuild install -target kextsymboltool DSTROOT=/tmp/kext_tools.dst
% (cd /tmp/kext_tools.dst; sudo pax -rw . /)