Re: [Xen-devel] shutdown question - PV vs HVM

[Russ Blaine <russell.blaine@xxxxxxx>]

Have a question on this old thread:

Keir Fraser wrote:
> For a PV guest, a shutdown node is written into xenstore which the guest
> picks up. The guest will then usually initiate a clean shutdown.
>
> The same happens for an HVM guest with PV drivers installed. If an HVM guest
> has no PV drivers (And so will obviously not be watching xenstore) then xend
> notifies the shutdown immediately to Xen. This causes Xen to immediately
> transition the guest to shutdown state, and no longer execute the guest,
> with no chance for clean shutdown. If there are no PV drivers installed,
> clean shutdown needs to be initiated from within the guest.
Why are HVM domains treated differently for shutdown? Guest OSes already know 
how to do a clean ACPI-initiated shutdown, so why not use that for shutdown in 
the presence of PV drivers?
The current method requires extra complexity in PV drivers. I imagine that it 
either fell out of porting PV drivers from PV domains to HVM domains or is just 
 paranoia about losing data during ACPI shutdown.
- R



>  -- Keir
>
> On 1/10/07 02:13, "James Harper" <james.harper@xxxxxxxxxxxxxxxx> wrote:
>
> > I've had a bit of a look through the code but can't seem to find the
> > answer to this question... what is the method by which 'xm' tells a
> > domain to shutdown?
> >
> > What is different about HVM that means it just powers straight off?
> >
> > Looking at the Linux source, it appears that something is done with
> > 'platform-feature-multiprocessor-suspend' in the store, but it isn't
> > clear to me what...
> >
> > Thanks
> >
> > James
> >
> >
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-devel
>
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--

-----------------------------------------------------
Russ Blaine | Solaris Kernel | russell.blaine@xxxxxxx

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