[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: [Xen-devel] Xen on top of xen
> -----Original Message----- > From: Koripella Srinivas [mailto:talkwithsrinivas@xxxxxxxxxxx] > Sent: 09 May 2007 19:53 > To: Petersson, Mats > Subject: Re: [Xen-devel] Xen on top of xen > > Can u throw more light on the non-nestability ?? Well, to put it simply, once you set up the SVM/VMX feature, it doesn't allow another such setup on top of it. It would be technically possible to support this in a processor designed to do so, but at the moment, neither of AMD's or Intel's CPU's support this. It is clearly easier to design a processor that only supports one level of "nesting" of virtualization[1], and it is also debatable what the REAL benefit of running nested virtual machines would be - I'm sure if it was a huge benefit compared to the effort of implementing it[2], at least one of the two producers of virtualizable x86 processors would have added such fearures... [1] Keeping one set of data for where to return to when the VMExit happens, for example, is easier than having a "stack" of such. [2] On top of the extra effort to design and test such feature, there is also a potential performance penalty for nesting VM's, since there is more logic involved. Depending on where that extra logic ends up, it may be necessary to add a further clock-cycle to some operation. -- Mats > > > ----- Original Message ---- > From: "Petersson, Mats" <Mats.Petersson@xxxxxxx> > To: pradeep singh rautela <rautelap@xxxxxxxxx>; Koripella > Srinivas <talkwithsrinivas@xxxxxxxxxxx> > Cc: xen-devel@xxxxxxxxxxxxxxxxxxx; > xen-devel-request@xxxxxxxxxxxxxxxxxxx > Sent: Wednesday, 9 May, 2007 4:33:57 PM > Subject: RE: [Xen-devel] Xen on top of xen > > > > > > -----Original Message----- > > From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx > > [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of > > pradeep singh rautela > > Sent: 09 May 2007 10:11 > > To: Koripella Srinivas > > Cc: xen-devel@xxxxxxxxxxxxxxxxxxx; > > xen-devel-request@xxxxxxxxxxxxxxxxxxx > > Subject: Re: [Xen-devel] Xen on top of xen > > > > > > > > On 5/9/07, pradeep singh rautela <rautelap@xxxxxxxxx> wrote: > > > > > > > > On 5/9/07, Koripella Srinivas < > > talkwithsrinivas@xxxxxxxxxxx > > <mailto:talkwithsrinivas@xxxxxxxxxxx> > wrote: > > > > Hi, > > Is it possible to run xen in a hvm guest which > > itself is running on xen? > > > > > > Yes, you can. > > > > > > Just to add only on hvm guests and not on pv guests. > > And you can't run HVM guests inside the "xen on top of xen", > as the HVM > feature is not (in current CPU's) nestable. > > -- > Mats > > > > > > > > Thanks > > ~psr > > > > > > > > > > Thanks > > > > > > ________________________________ > > > > Office firewalls, cyber cafes, college labs, > > don't allow you to download CHAT? Here's a solution! > > <http://us.rd.yahoo.com/mail/in/ymessenger/*http://in.messenge > > r.yahoo.com/webmessengerpromo.php> > > > > _______________________________________________ > > Xen-devel mailing list > > Xen-devel@xxxxxxxxxxxxxxxxxxx > > <mailto:Xen-devel@xxxxxxxxxxxxxxxxxxx> > > http://lists.xensource.com/xen-devel > > > > > > > > > > > > > > -- > > --- > > pradeep singh rautela > > > > "Genius is 1% inspiration, and 99% perspiration" - not me :) > > > > > > > > > > -- > > --- > > pradeep singh rautela > > > > "Genius is 1% inspiration, and 99% perspiration" - not me :) > > > > > > > > ________________________________ > > Office firewalls, cyber cafes, college labs, don't allow you > to download CHAT? Here's a solution! > <http://us.rd.yahoo.com/mail/in/ymessenger/*http://in.messenge > r.yahoo.com/webmessengerpromo.php> > _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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