Linux from Scratch
Toolchain built on Ubuntu 15.04 x86_64.
Target is x86_64.
Target is also whatever the Raspberry Pi 3 is.
Login as user lfs to your dev VM.
Make sure you have bash-glory and home applied to this user.
Insert the USB thumbdrive you prepared and attach to VM.
sudo $(command which mount-lfs.sh)
Do some work in /mnt/LFS.
sudo $(command which umount-lfs.sh)