Lguest is a Linux kernel x86 virtualization hypervisor introduced in kernel version 2.6.23 (released 9 October 2007) and removed in kernel version 4.14 (November 2017). The hypervisor is an operating system-level virtualization system capable of running unmodified 32-bit x86 Linux kernels as guest machines. Installation is as easy as running modprobe lg followed by tools/lguest/lguest to create a new guest.
Lguest can still be installed on kernel 4.14 and later through out-of-tree patches.
Lguest was maintained by Rusty Russell.
Lguest was unveiled in Januaryâ¯2007, when Jonathan Corbet described Rusty Russell's 6â¯000âÂÂline âÂÂrustyvisorâ as a minimal paravirtualised hypervisor intended mainly for education and experimentation.
The code was merged during the 2.6.23 development cycle and shipped in the 9 October 2007 release, together with Xen guest support. Running only on 32âÂÂbit x86 hosts, lguest relied on the new âÂÂâÂÂparavirt_opsâÂÂâ hooks; launching a guest involved loading the `lg` module and executing the userâÂÂspace lguest launcher.
As KVM and hardwareâÂÂassisted virtualization matured, interest in lguest dwindled. During the first half of the Linux 4.14 merge window the entire subsystem was deleted âÂÂdue to lack of interest and maintenance.â Rusty Russell subsequently announced the closure of the project's mailing list, noting that lguest had already been removed from the kernel.
Although no longer maintained upstream, communityâÂÂsupplied outâÂÂofâÂÂtree patches allow lguest to be built against newer kernels for teaching and experimentation.