Xen High-Performance x86 Virtualization Released

Xen Team writes "The University of Cambridge Computer Laboratory Systems Research Group is pleased to announce the open source release of Xen, a virtual machine monitor for x86. Xen lets you run multiple operating system images at the same time on the same PC hardware, with unprecedented levels of performance and resource isolation. Even under the most demanding workloads the performance overhead is just a few percent --- considerably less than alternatives such as VMware Workstation and User Mode Linux. This makes Xen ideal for use in providing secure virtual hosting, or even just for running multiple OSes on a desktop machine."

The Xen team continues: "Xen requires guest operating systems to be ported to run over it. Crucially, only the kernel needs to be ported, and all user-level application binaries and libraries can run unmodified. We have a fully functional port of Linux 2.4.22 running over Xen, and regularly use it for running demanding applications like Apache, PostgreSQL and Mozilla. Any Linux distribution should run unmodified over the ported kernel. With assistance from Microsoft Research, we have a port of Windows XP to Xen nearly complete, and are planning a FreeBSD 4.8 port in the near future.

"Visit the project homepage to find out more, and download the project source code or the XenDemoCD, a bootable 'live iso' image that enables you to play with Xen/Linux 2.4 without needing to install it on your hard drive. The CD also contains full source code, build tools, and benchmarks. Our SOSP paper gives an overview of the design of Xen, and evaluates the performance against other virtualization techniques.

"Work on Xen is supported by UK EPSRC grant GR/S01894, Intel Research Cambridge, and Microsoft Research Cambridge via an Embedded XP IFP award."

Re:I bet it's not Open Source...

[Trigun]

With assistance from Microsoft Research, we have a port of Windows XP to Xen nearly complete

They won't release the source for XP, but you can probably get a compiled binary. I just wonder if you'll have to re-register every time you change your virtual hardware.

MOL for x86?

[Realistic_Dragon]

In the same way that Mac On Linux makes moving people to Linux on a Mac pretty painless (just give them an icon for OSX in a window) this might do the same for migrating Windows users.

The biggest problem with emulators/virtualisation has always been speed. If a system can be set up that runs Linux but can boot XP easily and run fast, that will be a big improvement.

Of course it's not going to be much good for gamers (doesn't look like it can use hardware accelaration) but it's still pretty promising.

Re:Pfff

[JohnFluxx]

I got excitted that windows would be ported to use it.. but then:

"The Windows XP port is nearly finished. It's running user space applications and is generally in pretty good shape thanks to some hard work by the team over the summer. Of course, there are issues with releasing this code to others. We should be able to release the source and binaries to anyone that has signed the Microsoft academic
source license, which these days has very reasonable terms. We are in discussions with Microsoft about the possibility of being able to make binary releases to a larger user community. Obviously, there are issues with product activation in this environment which need to be
thought through."

It would be a bitch if it was ported, worked perfectly, but then nobody was able to use it.

The only thing I'm wondering...

[metroid composite]

...is if you can copy and paste between the OSs. That always annoyed me when I had Linux open remotely through a Windows machine. I had to leave a submission form open on my website as a "back door" to copy stuff in. This goes for things like Gnumeric to Excel data too.

Re:Pfff

[jdh28]

No, VMware runs unmodified binaries.

What they do provide is ready made installations of various operating systems you can just install, although you have to pay for these (well, the MS ones at least).

Re:MOL for x86?

[Anonymous Coward]

More like it allows people to run the two side by side and realise that on the Mac OS X is far superior to Linux as you can do so much more with it ..

Re:Pfff

[spektr]

The Windows XP port is nearly finished. It's running user space applications and is generally in pretty good shape thanks to some hard work by the team over the summer.

I'm surprised that this was possible at all with Windows XP. Microsoft's Shared Source program doesn't seem to be as useless as I thought.

Of course, there are issues with releasing this code to others. We should be able to release the source and binaries to anyone that has signed the Microsoft academic source license, which these days has very reasonable terms. We are in
discussions with Microsoft about the possibility of being able to make
binary releases to a larger user community.

I think there are two possibilities to do this. First, Microsoft incorporates the changes into their main trunk or releases patches for it. Second, Microsoft allowes a group of hackers to distribute modified Windows binaries. Both alternatives don't seem very probable.

User Mode Linux

[shird]

Sounds an awful lot like usermode linux. Get a vesion of the kernel/OS which makes calls to a host virtual machine rather than directly to the hardware for privileged instructions. Everything else can run directly through the CPU without being emulated because it is running in 'usermode' (or ring 1).

Re:Pfff

[kalidasa]

MS is one of their sponsors. How much you want to bet that MS licenses the technology and distributes it under their own logo? We already know from the VirtualPC purchase that this is a future direction for them.

Why Microsoft+Intel? NGSCB backward compatibility!

[NZheretic]

A quick glance over Xen group's paper [cam.ac.uk] leaves me very impressed with the performance these techniques can achieve. That the Xen group has decided to relase the code under the GPL leaves me very greatful. However, that both Intel Research and Microsoft Research has funded it, leave me somewhat concerned.

As I have stated before about Microsoft's purchase of Connectix's Virtual Server technology [oreillynet.com]

In my opinion Microsoft's acquisition of Connectix's Virtual Server technology has very little to do with running any other vendors operating system.

Microsoft needs a Virtual Server for backward compatibility for it's NGSCB ( Next Generation Secure Computing Base [microsoft.com] ) DRM ( Denial of Rights Mechanism [slashdot.org] ) platform.

Just as Microsoft's XP backward Win9x compatability opens up many locally exploitable API to gain SystemLocal privilege access, to the point where many programs need Adminstrator privilege to run, existing XP and win2k software would open up too many opportunities for helpfull hacker to bypass Microsoft's NGSCB DRM mechanisms.

Microsofts all too obvious solution is to provide a "Virtual" PC mode, running a modified XP and WinME, with the NGSCB providing virtual filesystems and hardware access. All, access of course, with the NGSCB DRM scanning and control.

Where do you want to go tomorrow?

The Electronic Frontier Foundation [eff.org] are about to publish a paper [com.com] criticizing a component of the "trusted computing" technology promoted by Microsoft, IBM and other technology companies, calling the feature a threat to computer users..

Source code not available

[avenj]

The source code is only available via BitKeeper, as far as I can tell from their site. The BitKeeper tools are not free software and cannot be used by anyone who has contributed to a competing product, according to the license for the free-as-in-beer version of BitKeeper. Is there somewhere else to get source and I'm just missing it?

Re:Not really like VMWare

[borgheron]

This depends on what is meant by "port". Is it possible that they mean that they have written drivers to work on those operating systems to make it work?

I believe more information is needed on this before I make any decision as to whether it's better or worse than VMware.

GJC

Re:Nice jab at Mozilla!

[seanmeister]

No, you haven't been trolled. Not by me, anyway. The text I quoted appears in the article as posted on /. [slashdot.org] ... I R'd TFA a bit later and saw that the actual article didn't mention Moz!

How many licenses per machine?

[Glonoinha]

Silly question about activation .. actually not -about- activation, but inspired by activitation :

If you only have a single computer with a single CPU, how many copies of WinXP do you need? That one is rhetorical of course, and the answer is One.

Can you run whatever software on that legitimately licensed WinXP machine that you like, assuming it was also legitimately licensed? That one is also rhetorical and the answer is Yes.

Now install VMware on that machine, WinXP as the host OS. By adding VMware you have not increased the number of CPUs or physical machines. If you created three virtual machines (if you had enough RAM and hard drive space, not a stretch at all) and wanted to run WinXP in each of those virtual machines simultaneously - do you need 1 license of WinXP or four licenses of WinXP (one for the host OS, and one for each VM)?

Granted the activation and active license management in XP may not allow this to happen even if in theory it should be allowed according to the 1 license / physical machine license in the EULA - but swap it with Windows 2000 or whatever ... what are the facts?

I am just curious.

NomadBIOS

[Anonymous Coward]

NomadBIOS [nomadbios.dk] did this a year ago, including swift migration of Guest OSes betweeen hosts, but with only two people and without a MS-research grant... But Xen looks nice, and the porting effort seems to be smaller.

Re:Pfff

[kma]

Someone was bitching "why can't XYZ OS run under VMWare if it runs perfectly well under generic PC hardware". Someone responded to the effect that VMWare was tuned to make certain concessions for the OSs they supported.

Right. The OS'es we "support." Not the OS'es "we're able to run." And those "concessions" are mostly performance trade-offs, not correctness.

It's still true that some OS'es don't run; but that's because our software has bugs. OS'es sometimes have bugs, too, though if the OS is important enough, we'll work around it. The bugs that prevent you from running the OS that some drunken Swede cooked up for course credit are admittedly less important to fix than the bugs that, say, prevent you from running Linux. However, in the long run, we try to fix even the bugs exposed only by drunken Swedes.

That's why AtheOS, OpenStep, BeOS, NetBSD, FreeDOS, B-Right, Plan9, QNX, and myriad other commercially unimportant OS'es run ok. Not because they're important to our customers (man, oh man, they aren't), but because they enable us to be sure our x86 virtualization layer is reasonably correct. That way, when Ingo Molnar decides to start using 80286-style 16-bit tasks with lots of grow-down and conforming code segments to do system calls in Linux 2.6, we won't get caught out too badly.

Xenify, anyone?

[leob]

With all the achievements in x86 binary code analysis, instrumentation and compilation (think of valgrind or Transmeta, to name just a few), wouldn't it be possible to read the kernel binary into some kind of a compiler, find all uses of the instructions that have to be replaced, replace them (and the adjoining code, if necessary) with the Xen interface calls, then reassemble and relink the kernel?

How extensive and how non-trivial are the necessary changes?