* Determining the location of the kernel source code
* Unable to find kernel sources at /usr/src/linux
* This package requires Linux sources.
* Please make sure that /usr/src/linux points at your running kernel, 
* (or the kernel you wish to build against).
* Alternatively, set the KERNEL_DIR environment variable to the kernel sources location
!!! ERROR: app-emulation/virtualbox-modules-1.3.8-r2 failed.