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Xen Hacker Interviewed
Drawoc Suomynona writes "The Xen virtual monitor is a new generation virtualization software that enable running multiple OSes at the same time with unprecedented level of performances. Manuel Bouyer was recently interviewed about his work porting Xen to the NetBSD operating system. The interview touches on why some consider Xen to be so good, how hard it is to integrate such a software package into an OS, and more."
>Linux is STILL for fags.
That's right, real men use BSD.
As I understand, vmware does do some limited emulation, at least VGA and Network cards. Xen instead traps all attempts to access the real devices in the machine and schedules them so that each operating system still thinks that they have full access to all of the real equipment. This requires some special kernel hooks, and that's why things like Windows and OS X aren't fully supported.
Also, I've seen this story in at least 3 places and I don't think it's right to say anyone ported Xen to NetBSD, NetBSD was updated (It's not exactly a "port") to take advantage of Xen features. It's possible that patches were sent to the Xen team to make things work more smoothly, but it's hardly porting.
HitScan
You're not understanding how Xen works. Xen doesn't let you run one OS inside another, they run side by side, almost as if they were two processes.
Running OSes inside of Xen and running MS Windows inside of Linux are two completely different things. If you can run MS Windows inside of Linux, whether or not that Linux kernel is running inside of Xen probably won't matter, since for that to work at all you probably have to trap any protected instructions and emulate them. Whether the emulation is implemented using actual ring 0 instructions or Xen hypervisor calls should be irrelevant.
However, you _can_ run Windows inside Xen, and people have done so. It's difficult to do because you need to manage to get a Windows source license and build your own copy with the necessary modifications, but not impossible.
Xen 3.0 on the newer Intel/AMD chips should be able to run Windows (or any other OS) without modification to the hosted OS.
You are correct and more so than you'd think. Xen provides true isolation of its dom-u's (user VM's). The xen hypervisor is most likely some of the most efficient code ever released to the open source community.
.. Dual xeon .. 3.2 .. 4GB Registered 2x 250 GB SATA disks (one of my labs)
...
.. well .. be more equal. Right now (afaic) Xen tips the scales in its direction.
.. so its sort of a triumph to see it finally getting a larger following :) Virtuozzo just cant *touch* it.
..
Xen layering and management allows you to do tons of stuff, I'm already doing SSI clusters on single machines. Xen + Win2k3 has been accomplished. This with CVIP / HA-LVS all running on one nic. Slice a high end p4 into a 6 + 1 (x 128) MB cluster of isolated servers. Its truly HA in a box, and very very simple.
The reason they call it a hypervisor is just that, its a step above a supervisory process. On VT enabled platforms (The new P4's / AMD's) you really start to see what xen can do without the bottlenecks of processor architecture.
Personally I think the ease of clustering is more important (and useful to the internet at large) than the ability to play with Windows stabalized under Linux. (I love saying that knowing its actually happened hehehehhe).
I can also say NetBSD does *very* well under xen.
Here's a really cool example config of how xen could slice up a high end dual xeon.
Assume
2 nics at 1000 MBPS, Connected to a gig-e switch. 100 MBPS x2 uplinks from 13 blended carriers. Basically, the average server you lease at any datacenter. Remember, you don't ever get to physically touch them. Xen is easy enough to install without needing local access.
You setup 2 smaller (maybe 256 MB each) netbsd firewalls , do some traffic shaping if you want. From there, you toss it over to an OpenSSI / Debian cluster running on the same machine.
Here's the really cool part. The bsd machines can talk to dom-0 and tell it when its time to drop nodes or add nodes, or make nodes bigger.
Need more servers? Simple . Xen them and load the ssi node image via pxe / etherboot.
Its very very easy then to setup the bridging needed to get a working cvip configuration and start weighting ports. So now you have 2 failover netbsd front end routers , failover LAMP and failover nics. Stick those SATA's in RAID1 and your only single point of faliure becomes your power supply or something going horribly wrong on domain 0. At the price it costs for those servers, you can afford 2 and pay under 500 bucks for the whole shebang if you lease them. Buying outright and co-locating is the best way. Or if your one of the fortunates with fiber coming into your own building
Now toss xen3 in there and you have yourself a win2k3 setup hosting your certificate authoirty, snaps, etc. bring it all into AD if you want. Its a networking "magic bag".
I'm just scratching the surface. These Guys Have a really, really useful wiki, as well as some "unofficial" Debian install packages. Your average Linux geek could get it going quickly.
Keep your eyes on Xen. Its going to do good things for everyone - and its going to push commercial equals to
Windows is just one of the marvels folks. Look at the big picture. Some of us have been screaming Xen for a while now
Off the soapbox. Hope someone found this useful. It took an awful long time to type. Course would help if I wasn't eating messy food