WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

Re: [Xen-devel] [PATCH 0 of 5] PV on HVM Xen

On Mon, 15 Mar 2010, Jeremy Fitzhardinge wrote:
> On 03/15/2010 05:28 AM, Stefano Stabellini wrote:
> > I like your pv clocksource implementation.
> > The only reason why I would defer the patch is that I don't particularly
> > like the "enable_pv" hypercall, so I would try to get away without it,
> > resetting the tsc offset automatically when enabling the VIRQ_TIMER on
> > an HVM domain.
> >    
> 
> Ah, so the issue is that if we're using the pvclock, the host and guest 
> need to share the same tsc, so we can't deal with any kind of tsc offset?
> 
> In that case, I'd prefer to have an explicit "set/remove tsc offset" 
> vcpu op rather than making it the implicit side-effect of anything 
> else.  In particular, since clock sources and event sources are 
> completely distinct, making tsc offset (a clock source thing) affected 
> VIRQ_TIMER (and event source thing) seems like a particularly poor idea.
> 
> That, or make the pvclock structure the HVM vcpu sees have timing 
> parameters which already incorporate the tsc offset.  We've already 
> demonstrated that there's no need to have the time info in the real 
> shared memory between Xen and the domain (it can be updated via copy 
> when needed).
> 
 
OK, you are right: having an explicit "set/remove tsc offset" is
the best solution.
Sheng, are you OK with this?


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel