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Re: [Qemu-devel] [RFC] Introduce vm_stop_permanent()
From: |
Daniel P. Berrange |
Subject: |
Re: [Qemu-devel] [RFC] Introduce vm_stop_permanent() |
Date: |
Tue, 2 Aug 2011 11:22:15 +0100 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Thu, Jul 28, 2011 at 10:31:43AM -0300, Luiz Capitulino wrote:
> On Thu, 28 Jul 2011 10:23:22 +0300
> Avi Kivity <address@hidden> wrote:
>
> > On 07/28/2011 12:44 AM, Blue Swirl wrote:
> > > On Wed, Jul 27, 2011 at 9:42 PM, Luiz Capitulino<address@hidden> wrote:
> > > > This function should be used when the VM is not supposed to resume
> > > > execution (eg. by issuing 'cont' monitor command).
> > > >
> > > > Today, we allow the user to resume execution even when:
> > > >
> > > > o the guest shuts down and -no-shutdown is used
> > > > o there's a kvm internal error
> > > > o loading the VM state with -loadvm or "loadvm" in the monitor fails
> > > >
> > > > I think only badness can happen from the cases above.
> > >
> > > I'd suppose a system_reset should bring the system back to sanity and
> > > then clear vm_permanent_stopped (where's -ly?)
>
> What's -ly?
>
> > > except maybe for KVM
> > > internal error if that can't be recovered. Then it would not very
> > > permanent anymore, so the name would need adjusting.
> >
> > Currently, all kvm internal errors are recoverable by reset (and
> > possibly by fiddling with memory/registers).
>
> Ok, but a poweroff in the guest isn't recoverable with system_reset
> right? Or does it depend on the guest?
>
> I get funny results if qemu is started with -no-shutdown and I run cont after
> a poweroff in a F15 guest. Sometimes qemu will exit after a few seconds,
> sometimes 'info status' will say 'running'.
libvirt uses this approach to fake a controlled soft reboot of guests.
eg
$ qemu .... -no-shutdown
...some time later...
system_shutdown
...wait for SHUTDOWN event...
system_reset
cont
Previous releases of QEMU had a bug in some device backends which would
cause a crash sometimes, but in general it ought to work IMHO.
Daniel
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