RE: [Xen-devel] how to keep time of windows pvhvm synchronized with host after resuming

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

As I understand it wc_sec + wc_nsec should give the number of nanoseconds since 
the Unix epoch at which the system was booted.

  Paul

> -----Original Message-----
> From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-devel-
> bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of ANNIE LI
> Sent: 16 September 2010 09:31
> To: xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: [Xen-devel] how to keep time of windows pvhvm synchronized
> with host after resuming
> 
> Hi
> 
> When the virtual machine is resumed from suspend, the guest
> operating
> system's wall-clock time remains at the value it had at the time of
> the
> suspension. For linux pvm, we can avoid resolve issue by setting
> independent_wallclock=0. However, HVM(or PVHVM) does not support
> this
> feature.
> 
> I did some investigation on how to implement this in windows
> para-virtualization driver. In \include\xen\interface\xen.h, there
> are
> several variables about timer such as: wc_sec and wc_nsec, and
> vcpu_time_info struct. It is very strange, wc_sec and wc_nsec is
> always
> zero for my windows vm with para-virtualization driver.
> Vcpu_time_info
> only contains time info for specific vcpu. Should i use those
> variables
> to get accurate time for VM? Is there any corresponding source code
> or
> algorithms available now? Is it safe to simply update vm time after
> resuming?
> 
> Citrix 5.6 Windows para-virtualization driver will notify windows
> kernel
> time change after resuming, and resumed windows vm with Citrix pv
> driver
> can keep it's time synchronized with host. Would you like to give me
> some clues about how to implement this?
> 
> Any help is greatly appreciated.
> 
> Thanks
> Annie
> 
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