[Xen-devel] Re: pvclock in userland (reprise)

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>>> Keir Fraser <keir.fraser@xxxxxxxxxxxxx> 17.09.09 21:03 >>>
>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.

Unless they sit in Xen's virtual space.

Jan


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