!!! This ebuild is from an overlay: '/usr/portage/local/layman/sabayon'
localhost ~ # emerge nvidia-drivers
--- Invalid atom in /etc/portage/package.unmask: x11-drivers/nvidia-drivers-1.0.
9755-r10
Calculating dependencies... done!
>>> Verifying ebuild Manifests...

>>> Emerging (1 of 1) x11-drivers/nvidia-drivers-1.0.9755-r10 to /
 * NVIDIA-Linux-x86-1.0-9755-pkg0.run MD5 ;-) ...                         [ ok ]
 * NVIDIA-Linux-x86-1.0-9755-pkg0.run RMD160 ;-) ...                      [ ok ]
 * NVIDIA-Linux-x86-1.0-9755-pkg0.run SHA1 ;-) ...                        [ ok ]
 * NVIDIA-Linux-x86-1.0-9755-pkg0.run SHA256 ;-) ...                      [ ok ]
 * NVIDIA-Linux-x86-1.0-9755-pkg0.run size ;-) ...                        [ ok ]
 * checking ebuild checksums ;-) ...                                      [ ok ]
 * checking auxfile checksums ;-) ...                                     [ ok ]
 * checking miscfile checksums ;-) ...                                    [ ok ]
 * checking NVIDIA-Linux-x86-1.0-9755-pkg0.run ;-) ...                    [ ok ]
 * Determining the location of the kernel source code
 * Found kernel source directory:
 *     /usr/src/linux
 * Could not find a usable .config in the kernel source directory.
 * Please ensure that /usr/src/linux points to a configured set of Linux sources                                                                                                                                                                                                                       .
 * If you are using KBUILD_OUTPUT, please set the environment var so that
 * it points to the necessary object directory so that it might find .config.

!!! ERROR: x11-drivers/nvidia-drivers-1.0.9755-r10 failed.
Call stack:
  ebuild.sh, line 1630:   Called dyn_setup
  ebuild.sh, line 702:   Called qa_call 'pkg_setup'
  ebuild.sh, line 44:   Called pkg_setup
  nvidia-drivers-1.0.9755-r10.ebuild, line 119:   Called linux-mod_pkg_setup
  linux-mod.eclass, line 464:   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 rel                                                                                                                                                                                                                       evant.
!!! A complete build log is located at '/var/tmp/portage/x11-drivers/nvidia-driv                                                                                                                                                                                                                       ers-1.0.9755-r10/temp/build.log'.

!!! This ebuild is from an overlay: '/usr/portage/local/layman/sabayon'
localhost ~ #