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xen-devel
[Xen-devel] Re: pvclock in userland (reprise)
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To: |
Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>, "Xen-Devel (E-mail)" <xen-devel@xxxxxxxxxxxxxxxxxxx> |
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Subject: |
[Xen-devel] Re: pvclock in userland (reprise) |
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From: |
Keir Fraser <keir.fraser@xxxxxxxxxxxxx> |
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Date: |
Thu, 17 Sep 2009 20:03:42 +0100 |
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Cc: |
"Nakajima, Jun" <jun.nakajima@xxxxxxxxx>, Jeremy Fitzhardinge <jeremy@xxxxxxxx>, "Dugger, Donald D" <donald.d.dugger@xxxxxxxxx>, Jan Beulich <JBeulich@xxxxxxxxxx> |
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Thu, 17 Sep 2009 12:04:19 -0700 |
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Aco3wIEUOMEVM/j+SGeKFmFaWmbhWgACRF3U |
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Thread-topic: |
pvclock in userland (reprise) |
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On 17/09/2009 18:58, "Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx> wrote:
> A remaining hard problem is that this single
> "userland-accessible shared page" must be somehow
> made available to apps (I suggested a rdmsr emulated
> by Xen so that it works in userland) and must be
> mapped into the app address space without kernel
> changes. I think someone (Keir?) suggested this
> problem was solveable before we got sidetracked
> on the need-vcpu-number-in-userland problem.
I don't think mapping things into application address space is really
possible without guest kernel changes. The guest kernel owns and manages the
pte that you'd be overwriting. Just blatting the pte would not be good form.
-- Keir
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