gistfile1.txt

wget http://distfiles.gentoo.org/releases/amd64/autobuilds/20180301T214503Z/stage3-amd64-nomultilib-20180301T214503Z.tar.xz
mkdir gentoo
sudo tar xaf stage3-amd64-nomultilib-20180301T214503Z.tar.xz -C gentoo
cd gentoo
for x in dev sys proc; do sudo mount --rbind {/,}$x; done
sudo cp -L {/,}etc/resolv.conf
sudo chroot . /bin/bash

IN CHROOT:

env-update
. /etc/profile
emerge --sync
emerge crossdev # installs sys-devel/crossdev-20171230::gentoo
mkdir -p /usr/local/overlay/crossdev/metadata
echo 'masters = gentoo' > /usr/local/overlay/crossdev/metadata/layout.conf
mkdir /etc/portage/repos.conf
echo '
[crossdev]
location = /usr/local/overlay/crossdev
masters = gentoo
' > /etc/portage/repos.conf/crossdev.conf

crossdev -t x86_64-test-linux-gnu
# FAIL:
#
# * Emerging cross-binutils ...
# * error: binutils failed :(
#
# in logs:
#
# [ebuild  N    ~] sys-libs/binutils-libs-2.30-r1  USE="nls -64-bit-bfd -multitarget -static-libs"
# [ebuild  N    ~] cross-x86_64-test-linux-gnu/binutils-2.30  USE="cxx nls -doc -multitarget -static-libs {-test}"
# 
# The following keyword changes are necessary to proceed:
#  (see "package.accept_keywords" in the portage(5) man page for more details)
# # required by cross-x86_64-test-linux-gnu/binutils-2.30::crossdev
# # required by cross-x86_64-test-linux-gnu/binutils (argument)
# =sys-libs/binutils-libs-2.30-r1 ~amd64

ACCEPT_KEYWORDS="~amd64" crossdev -t x86_64-test-linux-gnu