Talk:Xen/Archive 2007

Dom0 and Domu

http://wiki.xensource.com/xenwiki/OSCompatibility

what are they

dom0 as said in this talk page is the host os...and domU should be the guest os.

((above written by GNUtoo per Revision as of 00:38, 7 March 2006)

All the terminology of "host" and "guest" should be changed- Xen is not "hosted" by another OS- it loads first (by Grub) and then loads an OS into its first domain (dom0). This is different from what RTCore/RTLinux and VMWare do (except maybe VMWare ESX). --206.79.158.100 18:32, 16 July 2007 (UTC)

ring 1

I'm sure I read that zen ran the guest operating systems in ring 1. if this is true then a mention should probably be added to this article and to the rings 1 and 2 article. --Plugwash 11:37, 6 Jun 2005 (UTC)

I had thought that that was how it ran with virtualization extensions- Xen (or other hypervisors) would run in Ring 0, and the unmodified OS would run in Ring 1, all happy and unchanged. The modified OS are necessary when you have to run Xen in Ring 1 and force the OS into Ring 2, where an unmodiifed OS is unused to and would muck things up. --maru 17:21, 6 Jun 2005 (UTC)

Actually, Xen normally does run guest operating systems in Ring 1, which is why they need to be modified. When there is hardware support, a new axis is added: you have rings 0-3 and *also* "root mode" and "non-root mode". The hypervisor and other virtualisation software run in rings 0-3 of Root Mode (the hypervisor itself runs in ring 0, root mode) and see the real hardware. The guest runs in rings 0-3 of Non Root Mode, and so is prevented from seeing the real hardware and under complete control of the hypervisor. And yes, all of this information should probably be in the article somewhere ;-) I might get around to adding it later but if anyone else takes a crack at it then I can review it (I work on Xen fulltime). Cheers guys! --Mark Williamson 00:06, 7 Jun 2005 (UTC)

I was wondering how exactly you knew so much... But since I don't seem to have the whole ring thing quite right, I'll let you do it. --maru 00:25, 7 Jun 2005 (UTC)

Heh that's my secret :-) It's been great how many contributions this page has had - for months it had about one sentence on it, almost got deleted. I've tried to add stuff where I can but it'd be nowhere near as complete as it is without everyone else - I seem to remember you making a lot of the additions... Anyhow, I'll add the rings thing soon. But please do keep adding other stuff! --Mark Williamson 00:40, 7 Jun 2005 (UTC)

"The Xen host runs in Ring 0, while the guest runs in Ring 1." - Erm, correct me if I am wrong... the host OS Dom0 does NOT run in ring 0 only the Xen code runs in ring 0 not even the Dom0 runs in ring 0 which is why VMWare and KQEMU do not run on Xen kernels..... I believe it can be cited from the xensource mailing lists NthDegree 16:03, 18 February 2007 (UTC)

Fair use rationale for Image:Xen screenshot.png

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BetacommandBot 12:31, 6 July 2007 (UTC)

Fair use rationale for Image:Xen logo.gif

Image:Xen logo.gif is being used on this article. I notice the image page specifies that the image is being used under fair use but there is no explanation or rationale as to why its use in this Wikipedia article constitutes fair use. In addition to the boilerplate fair use template, you must also write out on the image description page a specific explanation or rationale for why using this image in each article is consistent with fair use.

Please go to the image description page and edit it to include a fair use rationale. Using one of the templates at Wikipedia:Fair use rationale guideline is an easy way to insure that your image is in compliance with Wikipedia policy, but remember that you must complete the template. Do not simply insert a blank template on an image page.

If there is other fair use media, consider checking that you have specified the fair use rationale on the other images used on this page. Note that any fair use images uploaded after 4 May, 2006, and lacking such an explanation will be deleted one week after they have been uploaded, as described on criteria for speedy deletion. If you have any questions please ask them at the Media copyright questions page. Thank you.

BetacommandBot 12:31, 6 July 2007 (UTC)

Undid discussion changes

Mostly all interesting parts of the discussion page were removed by somebody (206.79.158.100) without any reason: so I rolled back to the elder version. --Sophis 12:55, 24 August 2007 (UTC)

Virtual wars?

Hmm. I wonder whether it'd be relevant or neutral to mention that Xen seems to have won the FSF wars with regard to virtualization? ex: Xen gets some endorsements and support, and a startup- [1]. -- Maru Dubshinki 08:31 PM Thursday, 03 March 2005

I think that the XenSource startup company might be worth a mention, since it is basically the "xen company". As for being the winning any wars, I think it has a good chance of being the definitive open source virtualisation solution. However, I don't know that it has (yet) exceeded User Mode Linux, etc. in terms of deployments. I am also arguably biased about how good Xen is, so I've been sticking to largely technical content so far ;-) --Mark Williamson

I am actually wondering whether thinking of it as 'virtualization wars' is a red herring/moot point, what with the imminence this (~2005) year of AMD's and Intel's Pacifica and Vanderpool, respectively, techonologies. Actually, come to think of it, didn't AMD also contribute to Xen as well as Intel? -- Maru Dubshinki 12:49 PM Friday, 01 April 2005

Well, there'll still be competition between different virtual machine monitors sitting on top of those technologies. AMD have, I think, said that they will contribute to Xen but I don't believe they've made an actual code drop yet (Intel have already contributed a substantial amount). --Mark Williamson

I agree that there is a war... there is :

• qemu with the "proprietary-freeware" kernel module
• specific virtualisations such as uml
• Xen
• vmware "proprietary with free "testing" branch and free client"

look atentively at xen benchmark against uml...uml is a 2.4 kernel!!!...and uml patch has been integrated and avaliable by default inside the 2.6 branch since 2.6.??

--- It's not a war so much as a bake-off...

So how does the inclusion of KVM in the Linux kernel, as well as the announcement that Fedora Core 7 will include KVM effect Xen's position? If Linus Torvalds and RedHat are behind KVM, how long will RedHat remain in both camps before they decide to "officially support" one project over the other? --Alex Weeks 19:31, 20 February 2007‎ (UTC)