>>> Emerging (1 of 1) x11-drivers/nvidia-drivers-1.0.9626 to /
 * NVIDIA-Linux-x86_64-1.0-9626-pkg2.run MD5 ;-) ...                                                                                                  [ ok ]
 * NVIDIA-Linux-x86_64-1.0-9626-pkg2.run RMD160 ;-) ...                                                                                               [ ok ]
 * NVIDIA-Linux-x86_64-1.0-9626-pkg2.run SHA1 ;-) ...                                                                                                 [ ok ]
 * NVIDIA-Linux-x86_64-1.0-9626-pkg2.run SHA256 ;-) ...                                                                                               [ ok ]
 * NVIDIA-Linux-x86_64-1.0-9626-pkg2.run size ;-) ...                                                                                                 [ ok ]
 * checking ebuild checksums ;-) ...                                                                                                                  [ ok ]
 * checking auxfile checksums ;-) ...                                                                                                                 [ ok ]
 * checking miscfile checksums ;-) ...                                                                                                                [ ok ]
 * checking NVIDIA-Linux-x86_64-1.0-9626-pkg2.run ;-) ...                                                                                             [ ok ]
 * 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: x11-drivers/nvidia-drivers-1.0.9626 failed.
Call stack:
  ebuild.sh, line 1584:   Called dyn_setup
  ebuild.sh, line 665:   Called pkg_setup
  nvidia-drivers-1.0.9626.ebuild, line 106:   Called linux-mod_pkg_setup
  linux-mod.eclass, line 432:   Called linux-info_pkg_setup
  linux-info.eclass, line 554:   Called die

!!! Unable to calculate Linux Kernel version
!!! If you need support, post the topmost build error, and the call stack if relevant.