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Re: [Xen-devel] Passing information from HVM to Xen hypervisor

To: Priyanka Tembey <tembey.priyanka@xxxxxxxxx>
Subject: Re: [Xen-devel] Passing information from HVM to Xen hypervisor
From: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>
Date: Thu, 16 Sep 2010 16:04:49 +0100
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
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It depends on what information you want to pass.  Shared pages are
good to pass information to Xen if it's updated frequently, but Xen
doesn't necessarily need to know about each update.  (Paravirtualized
TPR would be a good example of this -- updated somtimes thoundands of
times per second, but only important if Xen is delivering an

For simplicity, I'd probably say start with a hypercall, and switch to
a shared page only if the overhead of making the VMEXITs is causing a
measurable performance problem.

Are you doing scheduler work?


On Thu, Sep 16, 2010 at 3:51 PM, Priyanka Tembey
<tembey.priyanka@xxxxxxxxx> wrote:
> hello,
> I want to pass some information about the HVM guest kernel from the HVM
> guest to the hypervisor (specifically, the scheduler). What is the best way
> to implement this and how should I go about it (hypercall vs. shared page)?
> I was taking a look at an old post related to a similar issue
> [http://xen.1045712.n5.nabble.com/Hypercall-from-HVM-guest-td2525175.html],
> but it wasn't very conclusive.
> thanks,
> Priyanka
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel

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