Hi, Can I run on DomU a Dom0 Kernel? So that This DomU will act as a Dom0 for other DomU on top of it? Thanks Sassy _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Am 11.02.2010 20:43, schrieb Sassy Natan: Hello.> Can I run on DomU a Dom0 Kernel? >Yes.> So that This DomU will act as a Dom0 for other DomU on top of it? >No. Stefan Kuhne _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Thu, Feb 11, 2010 at 2:54 PM, Stefan Kuhne <stefan.kuhne@gmx.net> wrote:>> So that This DomU will act as a Dom0 for other DomU on top of it? > No.DomU''s don''t run ''on top of'' Dom0. Dom0 is a virtual machine, just like any DomU. The only difference is that the Xen hypervisor gives it direct access to the hardware and the Xen controll API. with that, some userlevel processes on Dom0 manage shared resources access (mostly hard disk and network). Any Dom started after the first one have reduced access, so it can''t fight Dom0; but it uses the very same hypervisor API, so it can use (and usually do) the very same kernel as Dom0. it doesn''t give it any extra powers. Since the Xen hypervisor doesn''t run on Dom0 (it''s the other way around), to get nested virtualizations, you would have to run a second Xen hypervisor on top of the first hypervisor. AFAIK, Xen hasn''t been ported to the PV API, it needs the full, real hardware. -- Javier _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> > Since the Xen hypervisor doesn''t run on Dom0 (it''s the other way > around), to get nested virtualizations, you would have to run a second > Xen hypervisor on top of the first hypervisor. AFAIK, Xen hasn''t been > ported to the PV API, it needs the full, real hardware. > > > -- > Javier > > _ >Or run a Xen HVM and then you can run PVs inside of that (I''ve heard). We had a discussion here quite a long time ago about this. I''m not sure why Xen drags on nesting as other VM solutions provide it through hardware support (Mostly AMD). I''ve had the need for nested VMs so I can teach VMs. Each student would have their own VM which would allow them to act as though it were a Dom0 and run other VMs including the network. I''ll be testing this out later this quarter. Grant McWilliams Some people, when confronted with a problem, think "I know, I''ll use Windows." Now they have two problems. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Thu, Feb 11, 2010 at 09:43:59PM +0200, Sassy Natan wrote:> Hi, > > > Can I run on DomU a Dom0 Kernel? So that This DomU will act as a Dom0 for > other DomU on top of it?Can''t do with Xen. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Thu, 2010-02-11 at 14:43 -0500, Sassy Natan wrote:> Hi, > > > > > Can I run on DomU a Dom0 Kernel? So that This DomU will act as a Dom0 > for other DomU on top of it?Domains don''t stack. There''s no concept of one domain running on top of a different one, not even with the original dom0. But many of the tasks dom0 performs on behalf of domU''s could be done by other domUs as well. Primary example would be I/O virtualization for normal, non-privileged guests. So the dependency graph you can build for a ''service'' model is *much* more flexible than the rather static 3-level block scheme depicting the bare binary interface. That''s maybe not the answer you were looking for. If you''re rather looking for recursive virtualization, I don''t think that''s going to fly all that well either. Daniel _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
OK, Thanks for the answers Sassy On Thu, Feb 11, 2010 at 11:41 PM, Daniel Stodden <daniel.stodden@citrix.com>wrote:> On Thu, 2010-02-11 at 14:43 -0500, Sassy Natan wrote: > > Hi, > > > > > > > > > > Can I run on DomU a Dom0 Kernel? So that This DomU will act as a Dom0 > > for other DomU on top of it? > > Domains don''t stack. There''s no concept of one domain running on top of > a different one, not even with the original dom0. > > But many of the tasks dom0 performs on behalf of domU''s could be done by > other domUs as well. Primary example would be I/O virtualization for > normal, non-privileged guests. > > So the dependency graph you can build for a ''service'' model is *much* > more flexible than the rather static 3-level block scheme depicting the > bare binary interface. > > That''s maybe not the answer you were looking for. > > If you''re rather looking for recursive virtualization, I don''t think > that''s going to fly all that well either. > > Daniel > >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Sassy Natan wrote:> OK, > > Thanks for the answers > > Sassy > > On Thu, Feb 11, 2010 at 11:41 PM, Daniel Stodden > <daniel.stodden@citrix.com <mailto:daniel.stodden@citrix.com>> wrote: > If you''re rather looking for recursive virtualization, I don''t think > that''s going to fly all that well either. > > DanielIt''s called "nested virtualization" (not recursive) and there was a talk about it on the last Xen Summit in Shanghai. I suggest you to read the video: http://www.xen.org/files/xensummit_intel09/xensummit-nested-virt.pdf http://www.xen.org/media/Movies/XenSummitAsia09/2009-11-19-afternoon/NestedVirtualization.MTS Thomas _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
On Fri, Feb 12, 2010 at 03:46:34PM +0800, Thomas Goirand wrote:> Sassy Natan wrote: > > OK, > > > > Thanks for the answers > > > > Sassy > > > > On Thu, Feb 11, 2010 at 11:41 PM, Daniel Stodden > > <daniel.stodden@citrix.com <mailto:daniel.stodden@citrix.com>> wrote: > > If you''re rather looking for recursive virtualization, I don''t think > > that''s going to fly all that well either. > > > > Daniel > > > It''s called "nested virtualization" (not recursive) and there was a talk > about it on the last Xen Summit in Shanghai. I suggest you to read the > video: > > http://www.xen.org/files/xensummit_intel09/xensummit-nested-virt.pdf > http://www.xen.org/media/Movies/XenSummitAsia09/2009-11-19-afternoon/NestedVirtualization.MTS >These videos are also available on youtube: http://www.youtube.com/watch?v=D9pT0CHCx90 http://www.youtube.com/watch?v=puZfnzChZyA -- Pasi _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On 11/02/10 19:43, Sassy Natan wrote:> > Can I run on DomU a Dom0 Kernel? So that This DomU will act as a Dom0 > for other DomU on top of it? >No. The question makes no sense since both dom0 and domU both run on top of the bare metal xen hypervisor. jch _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Fri, Feb 12, 2010 at 3:13 AM, John Haxby <john.haxby@oracle.com> wrote:> On 11/02/10 19:43, Sassy Natan wrote: > >> >> Can I run on DomU a Dom0 Kernel? So that This DomU will act as a Dom0 for >> other DomU on top of it? >> >> > No. The question makes no sense since both dom0 and domU both run on top > of the bare metal xen hypervisor. > > jch > >It''s amazing how fast people will jump on a topic and respond without actually trying to figure out what he''s asking. He asked if a DomU could act as a Dom0 which is not the right way to ask the question (obviously by the number of "no" answers with no explanations). What I think he wants to do and the OP can correct me if I''m wrong is nest his VMs and currently this is possible but only to one level. Your DomU needs to be HVM and you can run more PV DomUs in it. This will change once Xen adds hardware nesting ability in Xen. Watch the Videos that were linked by Pasi and you can see that they''re working on it. KVM and VMware nest and I believe both are utilizing VM nesting in hardware. Grant McWilliams Some people, when confronted with a problem, think "I know, I''ll use Windows." Now they have two problems. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Thiago Camargo Martins Cordeiro
2010-Feb-12 15:06 UTC
[Xen-users] Re: [Xen-devel] DomU as Dom0?
You can run the Xen, the dom0 and some domUs whitin a KVM guest... On 11 February 2010 17:43, Sassy Natan <sassyn@gmail.com> wrote:> Hi, > > > Can I run on DomU a Dom0 Kernel? So that This DomU will act as a Dom0 for > other DomU on top of it? > > > > Thanks > > Sassy > > > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel > >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> Date: Fri, 12 Feb 2010 13:06:25 -0200 > From: Thiago Camargo Martins Cordeiro <thiagocmartinsc@gmail.com> > Subject: Re: [Xen-devel] DomU as Dom0? > To: Sassy Natan <sassyn@gmail.com> > Cc: xen-devel@lists.xensource.com, Xen List > <xen-users@lists.xensource.com> > Message-ID: > <6b7f6eb1002120706me206d81p5b211011dd21909d@mail.gmail.com> > Content-Type: text/plain; charset="iso-8859-1" > > You can run the Xen, the dom0 and some domUs whitin a KVM guest... > > On 11 February 2010 17:43, Sassy Natan <sassyn@gmail.com> wrote: > >> Hi, >> >> >> Can I run on DomU a Dom0 Kernel? So that This DomU will act as a Dom0 for >> other DomU on top of it? >> >> >> >> Thanks >> >> SassyYes, you can run Xen in a domU. However, as usual the devil is in the details. Just to clarify (because I don''t believe it has been said explicitly): It is entirely possible right now to run Xen + dom0 within an HVM domU. CPU support for hardware virtualization is a requirement. In truth, this has been the case for quite some, since the Xen 3.0 series, when HVM support started to firm up around 3.0.4. This mode of operation presents some challenges due the hardware emulated by qemu-dm, time skew, etc., but it has improved greatly with the latest Xen releases. This is the general idea of encapsulation: Xen { dom0, domU { Xen { dom0, domU, .. } }, ... } In general, this technique is useful for driver/hypervisor development, but it presents some limitations: -The nested Xen + dom0 can only support paravirtual guests. -Finicky dom0 kernels require boot-time tweaking (I can dig up my notes on the details if anyone is interested). -Paravirtual I/O from the nested dom0 to the "parent" dom0 is possible, but requires ugly driver hackery. -Usually slow. Very recent AMD/Intel processors, hardware assisted paging, etc reduce the pain, but certainly not completely. -Not what I would consider a production-ready/supportable environment. Good for development/experimentation/education only. There are quirks.. The above largely applies when running Xen+dom0+domUs within a vm on VMware / KVM / etc. All of that said, the nested virtualization capabilities present in KVM, those in the Xen pipeline (discussed in the summit presentation previously mentioned), VMware, and others do open the door to improvement in this area. Ultimately, I would suggest that interested parties give this a try. If needs are met, then it may be an entirely sufficient solution. At the very least, taking a trip down this particular rabbit hole will be informative :) Steve Maresca _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Fri, 2010-02-12 at 02:46 -0500, Thomas Goirand wrote:> Sassy Natan wrote: > > OK, > > > > Thanks for the answers > > > > Sassy > > > > On Thu, Feb 11, 2010 at 11:41 PM, Daniel Stodden > > <daniel.stodden@citrix.com <mailto:daniel.stodden@citrix.com>> wrote: > > If you''re rather looking for recursive virtualization, I don''t think > > that''s going to fly all that well either. > > > > Daniel > > > It''s called "nested virtualization" (not recursive) and there was a talk > about it on the last Xen Summit in Shanghai. I suggest you to read the > video: > > http://www.xen.org/files/xensummit_intel09/xensummit-nested-virt.pdf > http://www.xen.org/media/Movies/XenSummitAsia09/2009-11-19-afternoon/NestedVirtualization.MTSAh, nice. I didn''t expect VMX emulation be actually in the works somewhere. Cool, thanks for the link. "Recursive" was the original term for such a beast. Any estimates on the footprint? Small enough to be a candidate for inclusion? It''d certainly be interesting for some applications. Cheers, Daniel _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
WOW, This topic become a hot one. I in a middle of written an overview about virtualized the virtual. Thanks for all the pepole who respones to this email. I will send my papaer once I will finish it :-) Thanks for all Xen is really cool project! Sassy On Mon, Feb 15, 2010 at 12:16 PM, Daniel Stodden <daniel.stodden@citrix.com>wrote:> On Fri, 2010-02-12 at 02:46 -0500, Thomas Goirand wrote: > > Sassy Natan wrote: > > > OK, > > > > > > Thanks for the answers > > > > > > Sassy > > > > > > On Thu, Feb 11, 2010 at 11:41 PM, Daniel Stodden > > > <daniel.stodden@citrix.com <mailto:daniel.stodden@citrix.com>> wrote: > > > If you''re rather looking for recursive virtualization, I don''t > think > > > that''s going to fly all that well either. > > > > > > Daniel > > > > > > It''s called "nested virtualization" (not recursive) and there was a talk > > about it on the last Xen Summit in Shanghai. I suggest you to read the > > video: > > > > http://www.xen.org/files/xensummit_intel09/xensummit-nested-virt.pdf > > > http://www.xen.org/media/Movies/XenSummitAsia09/2009-11-19-afternoon/NestedVirtualization.MTS > > Ah, nice. I didn''t expect VMX emulation be actually in the works > somewhere. Cool, thanks for the link. > > "Recursive" was the original term for such a beast. > > Any estimates on the footprint? Small enough to be a candidate for > inclusion? It''d certainly be interesting for some applications. > > Cheers, > Daniel > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel >_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Daniel Stodden wrote:> On Fri, 2010-02-12 at 02:46 -0500, Thomas Goirand wrote: >> Sassy Natan wrote: >>> OK, >>> >>> Thanks for the answers >>> >>> Sassy >>> >>> On Thu, Feb 11, 2010 at 11:41 PM, Daniel Stodden >>> <daniel.stodden@citrix.com <mailto:daniel.stodden@citrix.com>> >>> wrote: If you''re rather looking for recursive virtualization, I >>> don''t think that''s going to fly all that well either. >>> >>> Daniel >> >> >> It''s called "nested virtualization" (not recursive) and there was aIt is just a name difference. It is actually recursivable as if the CPU is power enough.>> talk about it on the last Xen Summit in Shanghai. I suggest you to >> read the video: >> >> http://www.xen.org/files/xensummit_intel09/xensummit-nested-virt.pdf >> http://www.xen.org/media/Movies/XenSummitAsia09/2009-11-19-afternoon/NestedVirtualization.MTS > > Ah, nice. I didn''t expect VMX emulation be actually in the works > somewhere. Cool, thanks for the link. > > "Recursive" was the original term for such a beast. > > Any estimates on the footprint? Small enough to be a candidate for > inclusion? It''d certainly be interesting for some applications.It should be very small. Probably 2-3K LOC, we are still working on some tunning and polishing work. Thx, Eddie _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
On Mon, Feb 15, 2010 at 11:32 AM, Dong, Eddie <eddie.dong@intel.com> wrote:>>> It''s called "nested virtualization" (not recursive) and there was a > > It is just a name difference. It is actually recursivable as if the CPU is power enough.not if (as in this case) you use different requirements for each virtualization level. the ''real'' level needs HVM support to set an HVM DomU, where you can run Xen, but this level doesn''t have HVM, so you can only put PV DomU''s there. The KVM on KVM experiments are closer to being fully recursive. -- Javier _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Javier Guerra wrote:> On Mon, Feb 15, 2010 at 11:32 AM, Dong, Eddie <eddie.dong@intel.com> > wrote: >>>> It''s called "nested virtualization" (not recursive) and there was a >> >> It is just a name difference. It is actually recursivable as if the >> CPU is power enough. > > not if (as in this case) you use different requirements for each > virtualization level. the ''real'' level needs HVM support to set an > HVM DomU, where you can run Xen, but this level doesn''t have HVM, so > you can only put PV DomU''s there.You can distinguish in this way. The term "nested" actually comes from KVM side by Alexander Graf, though I don''t know why he chooses nested rather than recursive. What the Xen summit talked and we were approaching is exactly recursive virtualization.> > The KVM on KVM experiments are closer to being fully recursive.Yes. Eddie _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users