It can do a few things userns can't, like load kernel modules. I've had to use this to deal with bugs in BtrFS before.
http://user-mode-linux.sourceforge.net/
(another good site: https://wiki.archlinux.org/title/User-mode_Linux )
It can do a few things userns can't, like load kernel modules. I've had to use this to deal with bugs in BtrFS before.