localhost ~ # emerge ndiswrapper
Calculating dependencies... done!
>>> Verifying ebuild Manifests...

>>> Emerging (1 of 1) net-wireless/ndiswrapper-1.44 to /
 * ndiswrapper-1.44.tar.gz RMD160 ;-) ...                                                     [ ok ]
 * ndiswrapper-1.44.tar.gz SHA1 ;-) ...                                                       [ ok ]
 * ndiswrapper-1.44.tar.gz SHA256 ;-) ...                                                     [ ok ]
 * ndiswrapper-1.44.tar.gz size ;-) ...                                                       [ ok ]
 * checking ebuild checksums ;-) ...                                                          [ ok ]
 * checking auxfile checksums ;-) ...                                                         [ ok ]
 * checking miscfile checksums ;-) ...                                                        [ ok ]
 * checking ndiswrapper-1.44.tar.gz ;-) ...                                                   [ ok ]
 * See http://www.gentoo.org/doc/en/gentoo-kernel.xml for a list of supported kernels.

 * 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: net-wireless/ndiswrapper-1.44 failed.
Call stack:
  ebuild.sh, line 1654:   Called dyn_setup
  ebuild.sh, line 714:   Called qa_call 'pkg_setup'
  ebuild.sh, line 44:   Called pkg_setup
  ndiswrapper-1.44.ebuild, line 32:   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 relevant.
!!! A complete build log is located at '/var/tmp/portage/net-wireless/ndiswrapper-1.44/temp/build.log'.

localhost ~ #