Create .config

# ls -l /usr/src/linux
lrwxrwxrwx 1 root root 20 Aug 24 16:04 /usr/src/linux -> linux-3.14.14-gentoo
# make menuconfig

 if you finish that command,you can copy kernel`s .config

# xclip -sel clip < /mnt/gentoo/usr/src/linux/.config