lxc.cgroup.devices.allow = c 10:236 rwm
lxc.cgroup.devices.allow = b 252:* rwm
https://wiki.deimos.fr/LXC_:_Install_and_configure_the_Linux_Containers#LXC_control_device_mapper
sudo lxc.config
lxc.cgroup.devices.allow = c 10:236 rwm
lxc.cgroup.devices.allow = b 252:* rwm
lxc.aa_profile = unconfined
cat lxc.config | lxc config set ubuntu-vivid raw.lxc -
lxc config show <container-name>
lxc config device add <container> <device-tagname> <type> <key=value>
lxc config device add ubuntu-vivid loop-control unix-char path=/dev/loop-control