OpenBSD Journal

The Xen virtual machine monitor

Contributed by jose on from the virtual-computing dept.

cruel writes: "Xen is a virtual machine monitor for x86 that supports execution of multiple guest operating systems with unprecedented levels of performance and resource isolation. Xen is Open Source software, released under the terms of the GNU General Public License.

FreeBSD port is in the plans. OpenBSD? "

I know several people who are interested in this, including myself (I could do some testing with it). I think you'd also have to modify OpenBSD a bit to work within the system as a guest OS. Anyone have any experience playing with this on OpenBSD yet?

(Comments are closed)

  1. By raiten () on

    having a "iSeries like" with a simple x86 running multiple OpenBSD or others BSD, Linux or Windows.

    but for the security of this virtual network, it will depend of their abstraction layer so ... will see

    nonetheless, an very interesting project

  2. By Anonymous Coward () on

    Isn't avsm@ in that research group (SRG @ cambridge)?

    1. By Anil () avsm@ on mailto:avsm@

      Yeah, I got the NetBSD port fairly far along before abandoning it due to lack of time. If someone wants to work on the OpenBSD port, it's pretty straightforward now that the Xen interfaces have settled. Get in touch and I can point you in the right direction...

  3. By Torquemada Mudslide () on

    The thing that interests me: since the xen kernel can run on multi-processor machines and the actual os runs on the virtual cpu, could one concievably be gaining "multiprocessor" OpenBSD under this scheme?


    1. By Anil () avsm@ on mailto:avsm@

      It would be two completely separate instances of OpenBSD.

      1. By Anonymous Coward () on

        I think that the OP means that a multiprocessor machine could emulate a faster single-processor machine.

        1. By tedu () on

          not quite, but you could probably load-balance the two instances, or run different services on each.

    2. By Tobias Weingartner () Yeah right! on Whatever...

      It would be neater to have Xen be an abstraction layer to be used for a distributed memory/cpu machine. Have a collection (lab?) of machines act like a really large SGI origin (or whatever). Sure, some things are slow (network for memory updates), but in the end, if you have enough of them, and the right type of problem... who cares...

      1. By Anonymous Coward () on

        I think that'd be awesome too!

  4. By braddeicide () on

    "We have been working on porting 3 different operating systems to run
    on Xen: Linux 2.4, Windows XP, and NetBSD"

    Since they've been working with NetBSD, hopefully they make it a host OS soon, and since OpenBSD is much closer to NetBSD than FreeBSD we might get it before them :)

    1. By braddeicide () on

      Whoops, read further, the NetBSD port has stalled due to lack of manpower, doh.

  5. By Anonymous Coward () on

    Is this conceptually similar to VMWare (obviously except for the license) ??

    1. By Anonymous Coward () on

      I first read about it on SlashDot:

      From what I read...

      Both Xen and VMware are virtual machines.

      The main difference is that VMware tries to emulate (interrupts and all) an IA32 system, and Xen doesn't emulate it completely. You could have a chance at running anything on VMware(Inferno, BeOS, Novell), while with Xen you need to modify the OS slightly to run in the Xen virtual environment. The modifications you make to the OS significantly improve performance of the virtual machine running that environment. The SlashDot article includes a link to some impressive benchmarks that show that Xen is closer in performance to a native Linux OS than to the other virtual machines.

      Xen could become an ISP's dream - true virtual hosting, not just a chroot jail.

      This is all based off of just what I read. I haven't played with it yet, tho'. If anything I said is incorrect, please correct me.


      1. By Anonymous Coward () on

        Xen could become an ISP's dream - true virtual hosting, not just a chroot jail.

        Solaris 10 Zones could be impressive too.

  6. By grey () on

    I've been doing a bit of reading on xok (MIT exokernel & exos operating system based around its concept) and one paper that struck me as quite interesting was which talks about a virtual machine implemented for xok. Some interesting notes in the paper were that the vm need not be perfect in order to function properly, especially if the guest OS is targetted rather deliberately (in the case of the paper, the target guest OS was linux). This also echos some notions around the newer plex86/bochs project which serves to be a really lightweight virtualization element, just for linux guest OS's.

    Xen seems to be along similar lines of the newer plex86/bochs project; and even that xok project and doesn't really interest me as much per say; however the xok reading has been really fascinating. There don't seem to be any papers on it since 2000; but it's notable that OpenBSD was being used as an integral part of their development process, even as early as 2.2.

    Something conceptually like xok; while having a more general virtualization element seems like it could be really appealing, as it might eliminate many of the overheads associated with current generation virtualization & emulation attempts...

    Anyway, just rambling a little bit, but maybe someone else will find those to be similar conceptually, but more interesting as well.

    1. By Anonymous Coward () on

      Hi! Just wanted to say: it is more similair to Plex86 then to Bochs. Plex86 is aimed at x86 only, while Bochs is aimed at multiple archs. This also means there's a speed difference.

      For a more accurate description, see the pages of both projects. What i said is explained in an extensive way at the PLex86 page, iirc.

      Otoh, Xen is only x86, while the developers of Plex86 splitted op Bochs as a seperate project, with both a different purpose. Therefore, comparing it to Bochs isn't fair. They're not aimed at the same target.

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