user-mode-linux binary package in Ubuntu Precise i386

 User-mode Linux (UML) is a port of the Linux kernel to its own system
 call interface. It provides a kind of virtual machine, which runs
 Linux as a user process under another Linux kernel. This is useful
 for kernel development, sandboxes, jails, experimentation, and many
 other things.
 .
 This package contains the kernel itself, as an executable program,
 and the associated kernel modules.

Source package