After Xen and KVM, meet a new Linux hypervisor: Jailhouse

Devised for real-time use, open source Jailhouse hypervisor is lean and small, a complement to Xen and LVM rather than a replacement

In the world of hypervisors for Linux, a couple of names have come to the fore over time: Xen and KVM. But a new hypervisor called Jailhouse, designed for safety-critical and real-time use cases, made its public debut this week.

Originally announced late last year by Jan Kiszka, a consultant and software engineer at Siemens Corporate Technology, Jailhouse is a partitioning hypervisor that can run other OSes or applications designed for bare metal. To run it, one boots a conventional Linux system, starts Jailhouse, then partitions the system's resources to different "cells" that are each isolated from the others.

Unlike other hypervisors, though, Jailhouse is "optimized for simplicity rather than feature richness," as its GitHub notes put it. Functions like overcommitment of memory or CPU, for instance, aren't supported.

The GitHub notes for the project indicate that Jailhouse is very much a work in progress with its 0.1 release. However, "all major features required to use Jailhouse on Intel x86 CPUs are now available," according to the project mailing list. According to Kiszka, the smaller code base (and feature set) of Jailhouse makes it easier to maintain and certify for various safety standards.

Jailhouse's bare-bones approach is meant to make it more of a complement to existing and mature hypervisor technologies, rather than a replacement for them. "There are commercial hypervisors targeting at similar use cases [embedded and real-time systems], while Jailhouse is an open source effort," Kiszka said.

The main applications for Jailhouse, according to Kiszka, are "consolidated control systems" -- machine control, railway systems, energy generation/distribution, and so on. He noted that enterprise use "is typically not overlapping with our (currently foreseeable) user group." But added, "We don't want to exclude Jailhouse applications beyond our current scope; that's one reason why we opened it to the public."

Kiszka noted that there's growing interest in Jailhouse within telecom, for its hosting high-speed, low-latency networking functions -- which hints as to how Jailhouse could in time be adopted more directly by enterprises. If Jailhouse were to find a foothold in the enterprise environment, it wouldn't be the first time an open source technology not directly intended for enterprise use took off there.

This story, "After Xen and KVM, meet a new Linux hypervisor: Jailhouse," was originally published at InfoWorld.com. Get the first word on what the important tech news really means with the InfoWorld Tech Watch blog. For the latest developments in business technology news, follow InfoWorld.com on Twitter.

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