Monthly Archives: April 2017

Download server change for Xen releases

The official way to get the Xen hypervisor and other Xen Project downloads is via the the website. If you get Xen via the links on the website, you do not need to read the rest of this message.

We are aware that some users have been visiting the download server directly. That download server is changing.

In the past, the Xen Project has hosted its releases on space kindly provided on by Citrix (and, previously, XenSource). For some time now, we have in parallel made available downloads on the Xen Project’s server at

Starting right away, Xen Project releases will appear only on the Xen Project’s server.

The directory structure remains unchanged. So, you can replace
at the start of all urls, with
in all scripts, bookmarks, etc.

Previously published files will remain on, but new releases will not appear there.

Announcing Xen Project 4.9 RC and Test Day Schedule

Today, we created Xen 4.9 RC1 and will release a new release candidate every week, until we declare a release candidate as the final candidate and cut the Xen 4.9 release. We will also hold a Test Day every TUESDAY for the release candidate that was released the week prior to the Test Day starting from RC2. Note that RC’s are announced on the following mailing lists: xen-announce, xen-devel and xen-users. This means we will have Test Days on April 25th, May 2nd, 9th and 16th. Your testing is still valuable on other days, so please feel free to send Test Reports as outlined below at any time.

Getting, Building and Installing a Release Candidate

Release candidates are available from our git repository at

git:// (tag 4.9.0-<rc>)

where <rc> is rc1, rc2, rc3, etc. and as tarball from<rc>/xen-4.9.0-<rc>.tar.gz<rc>/xen-4.9.0-<rc>.tar.gz.sig

Detailed build and Install instructions can be found on the Test Day Wiki. Make sure you check the known issues section of the instructions before trying to download an RC.

Testing new Features, Test and Bug Reports

You can find Test Instructions for new features on our Test Day Wiki and instructions for general tests on Testing Xen. The following pages provide information on how to report successful tests and how to report bugs and issues.

Happy Testing!

Xen Project 4.8.1 is available

I am pleased to announce the release of Xen 4.8.1. Xen Project Maintenance releases are released in line with our Maintenance Release Policy. We recommend that all users of the 4.8 stable series update to the latest point release.

The release is available from its git repository;a=shortlog;h=refs/heads/stable-4.8
(tag RELEASE-4.8.1) or from the XenProject download page

These releases contain many bug fixes and improvements. For a complete list of changes, please check the lists of changes on the download pages.

Q&A with GlobalLogic on the Xen Project and Automotive Virtualization

The Xen Project is commonly used in embedded scenarios due to its security features, light-weight architecture and open source community. These core attributes are now making it more pervasive in the automotive industry, which has similar demands to the embedded industry, especially when it comes to security requirements.

To better understand how the Xen Project is used in the automotive space, we sat down with the folks at GlobalLogic to discuss updates on its Nautilus platform, which uses the Xen Project hypervisor; why they originally chose Xen; how hypervisors generally work in the automotive space; and the company’s upcoming plans with automotive virtualization.

Last year when we talked to GlobalLogic, you mentioned that GPU Virtualization was the next phase of automotive innovation. Where are you at in terms of implementing GPU Virtualization?

We have successfully implemented our Nautilus platform’s GPU virtualization feature for several Tier 1 automotive vendors (located in Japan, the US, and Europe). This was a big win for us and we learned a lot along the way and experienced some major benefits. Mainly, GPU virtualization has eliminated almost all performance degradation during the rendering of heavy 3D graphics scenes, allowing us to create a new level of IVI systems.

Why is the hypervisor important for automotive virtualization and GPU Virtualization in general? Why is Xen Project the hypervisor of choice for you within this space?

The hypervisor allows a significant decrease to the cost of automotive production and reduces the cost of BOM because the functions that were previously executed on different CPUs can be run on separate VMs. At the same time, GPU virtualization is beneficial in the process of 2D/3D graphics rendering. Therefore, the use of hypervisor enables building systems that perform better than their more expensive completely-hardware analogues.

Moreover, there are less processors per board, which leads to higher fail-safety. Essentially, a virtual system divided into a number of small subsystems is cheaper to maintain.

At the dawn of our project, GlobalLogic engineers considered various hypervisors, and finally decided that Xen Project was the most suitable solution because it is open source and has a rich history of application in various fields. Using the Xen Project, lets us concentrate on specific vehicle-related challenges instead of reinventing a virtualization solution.

What are the top three benefits you get from using the Xen hypervisor?

The first benefit that we have experienced is the decreased time to market for the manufacturers. Secondly, our customers get demos for free – if we used a proprietary product, we couldn’t afford this. Finally, it is great to experience the constant support of the global community and the community-driven approach to vulnerability detecting and fixing that we get with the Xen Project.

Were there any challenges with implementing Xen? How did you overcome these challenges?

The main challenges that we had with Xen and GPU virtualization was related to the different based ARM platforms. To overcome this, we developed a bench of drivers and extended the environment around them.

What are the next stages of growth for with automotive virtualization? Any trends that we should watch out for?

GlobalLogic is actively working on the commercialization of the Nautilus platform. We are expanding the GPU feature to a network of customers and vehicle models. At the same time, we are expanding the functionality of virtualization in areas like self-driving, advanced driver assistance systems (ADAS), connected services, safety, etc.

Xen Hypervisor to be Rewritten

The hypervisor team has come to the conclusion that using the C programming language, which is 45 years old as of writing, is not a good idea for the long term success of the project.

C, without doubt, is ridden with quirks and undefined behaviours. Even the most experienced developers find this collection of powerful footguns difficult to use. We’re glad that the development of programming languages in the last decade has given us an abundance of better choices.

After a heated debate among committers, we’ve settled on picking two of the most popular languages on HackerNews to rewrite the Xen hypervisor project. Our winners are Rust and JavaScript.

Rust, although not old enough to drink, has attracted significant attention in recent years. The hypervisor maintainers have acquainted themselves with the ownership system, borrow checker, lifetimes and cargo build system. We will soon start rewriting the X86 exception handler entry point, which has been a major source of security bugs in the past, and looks like an easy starting point for the conversion to Rust.

JavaScript has been a corner stone of web development since early 2000. With the advancement of React Native and Electron, plus the exemplary success of Atom and Visual Studio Code editors, it now makes sense to start rebuilding the Xen hypervisor toolstack in JavaScript. We’re confident that Node.js would be of great help when it comes to performance. And we believe Node.js and the current libxenlight event model is a match made in heaven.

Due to the improved ergonomics of the two programming languages, we expect developer efficiency to be boosted by factor of 10. We’re also quite optimistic that we can tap into the large talent pool of Rust and JavaScript developers and get significant help from them. We expect the rewrite to be finished and released within the year – by April 2018.

For those who want a more solid, tried and true technology, we are open to the idea of toolstack middleware being written in PHP and frontend JavaScript. But since maintainers are too busy playing with their new shiny toys, those who want PHP middleware will have to step up and help.

Stay put and get ready to embrace the most secure and easy to use Xen hypervisor ever, on April 1st 2018!

Note that this article was an April fools joke and was entirely made up.