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Xen Project Announces the 4.4 Release

By March 10, 2014March 6th, 2019Press Releases

Xen Project Community Releases Update to Enterprise Hypervisor Software

Open Source Virtualization Software Includes Additional ARM Support and Scalability for Cloud and Mobile Environments

SAN FRANCISCO, March 10, 2014–The Xen Project community, a Collaborative Project hosted at The Linux Foundation, today announced availability of the Xen Project Hypervisor version 4.4 with enhanced ARM support. The latest release also includes major performance and system scalability improvements for enterprise computing, such as mobile and cloud environments, where virtualization technology is increasingly in demand.

This release further advances the Project’s position as a fast, scalable, secure virtualization engine for the industry’s broadest range of server, workstation and low-power system on chip (SoC) devices.

Major contributions from AMD, Citrix, Intel, Oracle and SUSE are pushing the Xen Project software to take advantage of the latest hardware. Additionally, developers creating services and applications with embedded, mobile and cloud systems will benefit from the updated event channel implementation when scaling out their Infrastructure as a Service offerings.

“Virtualization and low-powered servers are leading companies to rethink the data center and its potential for efficiency,” said Lars Kurth, Chairman of the Xen Project advisory board. “Our solution contains IT-related costs, plus meets the security and scalability needs of today’s elastic cloud, mobile and social networking companies. The latest updates continue the Project’s track record of rich collaboration and widespread development from many of the world’s technology leaders. This certainly explains the significant growth of ARM support, which we’re pleased to see advance so quickly.”

Support for ARM on Xen Project Architecture Grows Quickly

The new release introduces significant stability, usability and performance improvements for the ARM architecture and extended hardware compatibility. AppliedMicro’s X-Gene, the Arndale Board, Calxeda ECX-2000, TI OMAP5 and the Allwinner SunXi boards are all supported. The substantially improved multiplatform capabilities of the hypervisor allow hardware and embedded vendors to port the Xen Project technology to new ARM SoCs easily, shortening their time to market.

Additional enhancements in this release included 64-bit guest support on ARMv8 platforms. All userspace tools, such as the xl management tool, can run on 64-bit and create 64-bit virtual machines out of the box.

The Xen Project hypercall ABI is now stable and will be maintained for backward compatibility, so users can trust future releases to boot older operating systems.

Extended support for ARM specific boot loaders and firmware interfaces, and support for physical partitions and LVM volumes to store disks of virtual machines is now available.

Improved Event Channel Scalability For Cloud Computing

The Xen Project team continues to drive innovation and collaboration around server virtualization and the cloud. Powering many of the largest clouds in production today, including Amazon EC2, Rackspace Cloud and others, the community understands the need to run more virtual machines on a single host.

Yet demands on hypervisor scalability continue to increase, both from larger machines, new workloads such as virtual desktop infrastructures (VDI) and new cloud OS technologies, including MirageOS, ErlangOnXen, OSv, and HalVM. Recognizing that high-availability and stability are critical to VDIs and cloud deployments, the XenServer team at Citrix contributed the new event channel implementation to the Xen Project codebase. To help eliminate workload limitations for users, this enables the hypervisor to run thousands of guests on a single physical machine.

Experimental Support for PVH Mode for Guest

Oracle has contributed a functional preview of a new virtualization mode called PVH currently available to virtualized guests. PVH is an extension to the classic Xen Project Paravirtualization (PV) that uses the hardware virtualization extensions available on modern x86 processors. PVH uses PV drivers for boot and I/O, and Intel hardware virtualization extensions for page table operations, system calls and other privileged operations. This not only improves performance and security, but also simplifies the architecture and Xen Project Hypervisor-Linux interface significantly.


“PVH is a major development for Xen Project software on x86 and has the potential to greatly simplify the Linux interface in due time, “said Wim Coekaerts, Senior Vice President, Linux and Virtualization Engineering, Oracle. “We expect PVH to have the best characteristics of all virtualization modes — a simple, fast, secure interface, with low memory overhead that also takes full advantage of the latest hardware.”


Additional key updates include:

● Better performance with modern storage devices and big data — Indirect descriptors for block PV protocol (Linux) allow each individual request to triple in size, greatly improving I/O performance when running on fast storage technologies such as solid-state drive and RAID. Available in any guest running Linux 3.11 or higher (regardless of Xen Project version).

● More powerful driver domains — Disk driver domains can now uniformly run block scripts and user-space backends, such as qdisk, bringing them up to feature parity with domain 0. This means host administrators can take advantage of the enhanced security, scalability, and robustness provided by driver domains without sacrificing the wide array of disk configuration options provided by Xen in dom0.

● New SPICE protocol support — Functionality, such as clipboard sharing and USB redirection, creates a much richer connection for virtual desktops and better graphics performance.

● Enhanced diagnostics and kexec debug support — When a crash happens, a special kernel is allowed to immediately collect information about the root cause, offering developers better diagnosis and repair abilities.

The 4.4 release is the result of a broad, collaborative development effort representing engineers from more than 13 leading hardware, software and security vendors. Top contributors include Amazon, AMD, Analog Devices, Broadcom, Citrix, Fujitsu, Intel, Linaro, NSA, Oracle, SUSE, Verizon/Terremark, along with numerous individual and academic institutions. The new release is available to download from the website today:

About Xen Project

The Xen Project software is an open source virtualization platform licensed under the GPLv2 with a similar governance structure to the Linux kernel. Designed from the start for cloud computing, the Project has more than a decade of development and is being used by more than 10 million users. A Collaborative Project at The Linux Foundation, the Xen Project community is focused on advancing virtualization in a number of different commercial and open source applications including server virtualization, Infrastructure as a Service (IaaS), desktop virtualization, security applications, embedded and hardware appliances. It counts many industry and open source community leaders among its members including: Amazon Web Services, AMD, ARM, Bromium, Calxeda, CA Technologies, Cisco, Citrix, Google, Intel, Oracle, Samsung and Verizon. For more information about the Xen Project hypervisor and to participate, please visit

Sarah Conway
The Xen Project
Media Contact