BOOST_ROOT = $(.boost-build-file:D) ;
if --v2 in $(ARGV)
{
    if $(JAM_VERSION:J="") < 030105
    {
        ECHO "error: Boost.Jam 3.1.5 or later required" ;
        EXIT ;
    }
    else
    {
        JAMFILE = [Jj]amfile.v2 ;
        boost-build tools/build/kernel ;
    }   
}
else
{
    boost-build tools/build ;
}