"** kmk (variable KBUILDDIR) not found!"什么意思?

root@HAH-Linux:~# cd /home/hah/pro/virtualbox
root@HAH-Linux:/home/hah/pro/virtualbox# ./configure
Checking for environment: Determined build machine: linux.x86, target machine: linux.x86, OK.
Checking for kBuild:
  ** kmk (variable KBUILDDIR) not found!

没看懂。。。