Re: [kvm-devel] [PATCH 1/4] Add helper functions for paravirtual clocksources.

[Gerd H. <kr...@re...>]

Glauber Costa wrote:

> This is not exactly what kvm does. For us, wallclock read and system
> time reads are decoupled operations, controlled by different msrs.

Same for xen.  Although both live in the shared_info page they are
updated independently (and the wall clock is updated much less frequently).

> This function might exist, but in this case, it have to be wrapped
> around a kvm_read_wallclock(), that does the msr read. (I'm not sure
> whether or not you do it in your later patches, doing sequential reads
> :-) )

It is, as you have seen in the kvm patch ;)

What is the reason to handle the two clock msrs in different ways btw?
I think it would be better to have both msrs work the same way though,
i.e. the wallclock msr should have a enable bit and should auto-update too.

cheers,
  Gerd

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