From: Russ Blaine <russell.blaine@sun.com>
To: Keir Fraser <Keir.Fraser@cl.cam.ac.uk>
Cc: James Harper <james.harper@bendigoit.com.au>,
xen-devel@lists.xensource.com
Subject: Re: shutdown question - PV vs HVM
Date: Wed, 03 Sep 2008 11:01:30 -0700 [thread overview]
Message-ID: <48BED0FA.5070409@sun.com> (raw)
In-Reply-To: <C3264401.E413%Keir.Fraser@cl.cam.ac.uk>
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@bendigoit.com.au> 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@lists.xensource.com
>> http://lists.xensource.com/xen-devel
>
>
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel
--
-----------------------------------------------------
Russ Blaine | Solaris Kernel | russell.blaine@sun.com
next prev parent reply other threads:[~2008-09-03 18:01 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-01 1:13 shutdown question - PV vs HVM James Harper
2007-10-01 5:28 ` Keir Fraser
2007-10-05 13:48 ` James Harper
2007-10-05 13:49 ` Keir Fraser
2007-10-06 7:29 ` James Harper
2007-10-06 8:17 ` James Harper
2007-10-06 8:42 ` Keir Fraser
2007-10-06 9:42 ` James Harper
2008-09-03 18:01 ` Russ Blaine [this message]
2008-09-03 19:02 ` Keir Fraser
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