Hello, All. Please tell me what hardware platforms is supported by Xen except i386 and IA64, and what is the amount of the support? I mean is absent, partial, experimental or full. My interest is about the architectures: * PPC * ARM As far as I know there no more architectures supported by Xen (or even planned to support). And question #2. Theoretical. Will recursive virtualization be possible in Xen in future or it''s more likely that some new virtualization systems will emerge that will be able to virtualize recursively? -- WBR, i.m.chubin _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Hi there,> Please tell me what hardware platforms is supported > by Xen except i386 and IA64, > and what is the amount of the support?Don''t forget x86_64, which I think is fairly well supported.> I mean is absent, partial, experimental or full. > > My interest is about the architectures: > * PPCThere''s code for Xen on PPC in the tree. Last I heard, it was not production ready yet. I don''t think I''ve seen much from the IBM developers who were working on this for a while, so I''m not sure what the status of the work is.> * ARMThere are some developers working on this; I believe they''re working on Xen for deployment on Smart Phones, etc. See: http://lists.xensource.com/archives/html/xen-devel/2007-08/msg00428.html http://xen.xensource.com/files/xensummit_4/Secure_Xen_ARM_xen-summit-04_07_Suh.pdf http://xen.org/files/xensummit_fall07/14_SangBumSuh.pdf These are just some random links I thought might help. There may be others out there you''d find worth reading.> As far as I know there no more architectures > supported by Xen (or even planned to support).Not that I know of; I''ve heard the idea of a MIPS port mentioned but I''ve no idea if that will ever be tackled by anyone.> And question #2. > Theoretical. > > Will recursive virtualization be possible in Xen > in future or it''s more likely that some new > virtualization systems will emerge that will > be able to virtualize recursively?You can get one step towards nesting Xens by running Xen + PV domains in a Xen HVM domain. It will never be possible nest Xen instances using pure PV, you''d need HVM support. Arbitrary nesting of Xens could be implemented using HVM if each "host" Xen emulates the behaviour of the HVM instructions for its "guest" Xen instance. This emulation code has not been implemented to date and I''ve not seen any suggestion that somebody is working on it. But it is theoretically possible (might perform really badly, though futurehardware support could reduce the overhead a bit). You can nest QEmu virtual machines already but the acceleration options mightn''t work, I guess, so it would probably be pure emulation. Cheers, Mark -- Push Me Pull You - Distributed SCM tool (http://www.cl.cam.ac.uk/~maw48/pmpu/) _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Mark, thank you for your answers.
Short summary.
Supported hardware platforms:
* i386
* x86_64
* IA64
Support is developing for the platforms:
* PPC (stalled)
* ARM (poor)
* MIPS port mentioned
And another question.
Can I run a 64-bit HVM-domain in a 32-bit host system?
Dom0 domU
32 32 Ok
32 64 ??
64 32 Ok
64 64 Ok
As far as I can understand it is possible
but hypervisor (and domain0) should be PAE-enabled.
--
WBR, i.m.chubin
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Igor Chubin schrieb:> Mark, thank you for your answers. > > Short summary. > > Supported hardware platforms: > > * i386 > * x86_64 > * IA64 > > Support is developing for the platforms: > > * PPC (stalled) > * ARM (poor) > * MIPS port mentioned > > > > > And another question. > > > Can I run a 64-bit HVM-domain in a 32-bit host system? > > > > Dom0 domU > 32 32 Ok > 32 64 ?? > 64 32 Ok > 64 64 Ok > > > As far as I can understand it is possible > but hypervisor (and domain0) should be PAE-enabled.No, it''s not possible - how should that work (and why would you want to do it)? If you really need to start 64bit guests on a 32bit host, you may have some luck with Qemu emulation, though. -- Tomasz Chmielewski http://wpkg.org _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> > Supported hardware platforms: > > > > * i386 > > * x86_64 > > * IA64 > > > > Support is developing for the platforms: > > > > * PPC (stalled)At this stage I''d rather say "unknown", because I really don''t know what''s happening.> > * ARM (poor)I''d say "in progress" - it''s not available in mainline Xen yet, but companies do seem to have some sort of commitment to making it work.> > * MIPS port mentionedNo idea if this was mentioned seriously, or just tossed about as an idea.> > Can I run a 64-bit HVM-domain in a 32-bit host system? > > > > > > > > Dom0 domU > > 32 32 Ok > > 32 64 ?? > > 64 32 Ok > > 64 64 Ok > > > > > > As far as I can understand it is possible > > but hypervisor (and domain0) should be PAE-enabled. > > No, it''s not possible - how should that work (and why would you want to > do it)? > > If you really need to start 64bit guests on a 32bit host, you may have > some luck with Qemu emulation, though.You can, in fact, run a 32-bit PAE dom0 and a 64-bit domU, provided Xen itself is 64-bit. This might even perform better than using a 64-bit dom0, due to various differences between x86_64 and x86_32 - it''s crazy stuff. There used to be some limitations on whether suspend / resume / live migration worked when dom0 and domU were in different x86 modes. This restriction may have been lifted since I last saw it mentioned. Cheers, Mark -- Push Me Pull You - Distributed SCM tool (http://www.cl.cam.ac.uk/~maw48/pmpu/) _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Mark Williamson schrieb:>>> Supported hardware platforms: >>> >>> * i386 >>> * x86_64 >>> * IA64 >>> >>> Support is developing for the platforms: >>> >>> * PPC (stalled) > > At this stage I''d rather say "unknown", because I really don''t know what''s > happening. > >>> * ARM (poor) > > I''d say "in progress" - it''s not available in mainline Xen yet, but companies > do seem to have some sort of commitment to making it work. > >>> * MIPS port mentioned > > No idea if this was mentioned seriously, or just tossed about as an idea. > >>> Can I run a 64-bit HVM-domain in a 32-bit host system? >>> >>> >>> >>> Dom0 domU >>> 32 32 Ok >>> 32 64 ?? >>> 64 32 Ok >>> 64 64 Ok >>> >>> >>> As far as I can understand it is possible >>> but hypervisor (and domain0) should be PAE-enabled. >> No, it''s not possible - how should that work (and why would you want to >> do it)? >> >> If you really need to start 64bit guests on a 32bit host, you may have >> some luck with Qemu emulation, though. > > You can, in fact, run a 32-bit PAE dom0 and a 64-bit domU, provided Xen itself > is 64-bit. This might even perform better than using a 64-bit dom0, due to > various differences between x86_64 and x86_32 - it''s crazy stuff.I meant running a 64bit guest running on a 32bit host sitting on a 32bit hardware. It''s not possible, unless emulated. -- Tomasz Chmielewski http://wpkg.org _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
...>> You can, in fact, run a 32-bit PAE dom0 and a 64-bit domU, provided Xen >> itself is 64-bit. This might even perform better than using a 64-bit >> dom0, due to various differences between x86_64 and x86_32 - it''s crazy >> stuff. > > I meant running a 64bit guest running on a 32bit host sitting on a 32bit > hardware. > It''s not possible, unless emulated. >My question was not about hardware of course. Thank you Mark, thank you Thomasz. New crazy questions. Is it possible to make PCI passthrough without domU stopping? I know that I can hide devices from dom0 without reboot, but what about hot PCI devices passing? Is it possible? And another question. What do you think about the idea: Is it possible (at least theoretically) to change dom0 into domU and some domU into dom0 without rebooting the system? AFAIU, to do this we should pass all dom0 devices to another domain and after that make reattaching of the running domUs devices from current dom0 to the "new dom0". Or more easy task. Presume, we have maid lightweight dom0 that uses initrd only (he also can use external devices when booting new domains). And than we have maid lightweight domU (DOMAIN1) that uses initrd only. It does not use network and disks. At some point we have these two domains running (dom0 and DOMAIN1). None of them uses disk and network. Can we make change DOMAIN1 into dom0 (and former dom0 into say DOMAIN2)? Or it''s crazy idea ant it''s better not to think about it? -- WBR, i.m.chubin _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> New crazy questions.Good :-)> Is it possible to make PCI passthrough without > domU stopping?There were some patches posted recently to allow PCI devices to be hot-plugged and hot-unplugged into a privileged domU. I *think* they even allowed you to hot-unplug PCI devices and then migrate the domain (you can''t ordinarily migrate a domain which has PCI devices passed through to it).> I know that I can hide devices from dom0 > without reboot, but what about hot PCI devices passing? > Is it possible?The patches that make it possible are already in xen-unstable, I believe. See: http://xenbits.xensource.com/xen-unstable.hg?rev/3f407392da49 This looks like you can now hot-add and -remove PCI devices from PV guests. I think other changesets also made it possible for HVM guests if you have VT-d hardware. I''ve not tried this and I don''t know if there are any special requirements in the guest kernel, in order for it to handle this.> Is it possible (at least theoretically) to change dom0 into domU and > some domU into dom0 without rebooting the system? > AFAIU, to do this we should pass all dom0 devices to > another domain and after that make reattaching of the > running domUs devices from current dom0 to the "new dom0".Ah, well that''s an interesting question. There are a lot of devices that would need passing over and not all of them would be PCI devices. So you couldn''t do it just with hotplug. In fact, simple PCI hotplug isn''t enough on its own, since a domain that''s had a PCI device passed through to it still has to occasionally get help from dom0, which is more privileged. Pretty much anything is possible if you put your mind to it, but I don''t think I''m qualified to say whether doing this would be worthwhile in terms of effort (or efficient in terms of performance). You''d not only need the new dom0 to take over the low level devices in the system, you''d also need to keep the management state (Xend''s state, xenstored''s state) in sync between the old dom0 and the new dom0 so that it could go on managing the domUs correctly. I think it would be quite tricky to get this working, though!> Or more easy task. > > Presume, > we have maid lightweight dom0 > that uses initrd only (he also can use external devices > when booting new domains). > And than we have maid lightweight domU (DOMAIN1) > that uses initrd only. It does not use network and disks. > > At some point we have these two domains running (dom0 and DOMAIN1). > None of them uses disk and network. > > Can we make change DOMAIN1 into dom0 (and former dom0 into say DOMAIN2)?Again, the problem is in all the low level transfers of control. It''s still going to be a problem here. Again, it''s probably doable with enough coding skill and low level knowledge but would be very tricky.> Or it''s crazy idea ant it''s better not to think about it?It''s not a crazy idea - you might want (for instance) to have a "failsafe" dom0 that kicks in if the primary dom0 dies. However, nobody (that I know of) has done this yet and that''s at least partly because it''s a hard problem ;-) Definitely interesting to think about, though! Cheers, Mark -- Push Me Pull You - Distributed SCM tool (http://www.cl.cam.ac.uk/~maw48/pmpu/) _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users