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RE: [Xen-ia64-devel] [Q]About Domain time update in IA64


  • To: "Atsushi SAKAI" <sakaia@xxxxxxxxxxxxxx>, <xen-ia64-devel@xxxxxxxxxxxxxxxxxxx>
  • From: "Tian, Kevin" <kevin.tian@xxxxxxxxx>
  • Date: Thu, 11 May 2006 11:03:02 +0800
  • Delivery-date: Wed, 10 May 2006 20:03:37 -0700
  • List-id: Discussion of the ia64 port of Xen <xen-ia64-devel.lists.xensource.com>
  • Thread-index: AcZ0pRA9FWgXU7prT0mppYMX+rrVDAAAOBaA
  • Thread-topic: [Xen-ia64-devel] [Q]About Domain time update in IA64

>From: Atsushi SAKAI
>Sent: 2006年5月11日 10:45
>
>Hi All
>
> I have a question about Domain time update in IA64.
>(update_vcpu_system_time)
>
>In x86, this function is working.
>But in ia64, the function is null at this moment.
>Is there any plan to change the function specification ?
>
>Atsushi Sakai

Now xen/ia64 has a different time virtualization policy as xen/x86. 
For xen/x86, the whole virtual timer source is based on above system 
time updated by a regular soft timer. For xen/ia64, xen is only 
responsible for emulating virtual itc/itm. When virtual timer can be 
triggered depends on the virtual itm value set by guest. Xen injects 
virtual timer interrupt into guest and it's guest itself to maintain the 
system time. This policy works for platform with ITC as timer source, 
which however can't support platform with ITC driven by different 
frequency. For those systems, normally a global platform timer 
resource will be provided. Then who owns platform timer resource 
and how domain and xen cooperate to achieve virtual value will be 
topic to be investigated later.

Thanks,
Kevin

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