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Re: [Qemu-devel] [RFC] Introduce vm_stop_permanent()
From: |
Luiz Capitulino |
Subject: |
Re: [Qemu-devel] [RFC] Introduce vm_stop_permanent() |
Date: |
Thu, 28 Jul 2011 15:00:07 -0300 |
On Thu, 28 Jul 2011 19:52:31 +0200
Jan Kiszka <address@hidden> wrote:
> On 2011-07-28 19:48, Luiz Capitulino wrote:
> > On Thu, 28 Jul 2011 14:39:23 -0300
> > Luiz Capitulino <address@hidden> wrote:
> >
> >> On Thu, 28 Jul 2011 17:20:41 +0200
> >> Jan Kiszka <address@hidden> wrote:
> >>
> >>> On 2011-07-28 17:18, Luiz Capitulino wrote:
> >>>> On Thu, 28 Jul 2011 16:19:19 +0200
> >>>> Jan Kiszka <address@hidden> wrote:
> >>>>
> >>>>> On 2011-07-28 15:37, Avi Kivity wrote:
> >>>>>> On 07/28/2011 04:31 PM, 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?
> >>>>>>>
> >>>>>>
> >>>>>> permanent-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?
> >>>>>>
> >>>>>> Right, it's not recoverable if you shut the power down where the
> >>>>>> tractor
> >>>>>> beam is coupled to the main reactor.
> >>>>>
> >>>>> system_reset will bring all emulated devices back into their power-on
> >>>>> state - unless we have remaining bugs to fix. Actually, one may consider
> >>>>> issuing this reset automatically on vm_start after "permant" vm_stop.
> >>
> >> The only permanent vm_stop we'd have is poweroff when -no-shutdown is used.
> >>
> >> Are you saying that system_reset should be able to recover from that too?
> >
> > It already does, so we don't have permanent stops.
>
> Exactly. We just have stops over inconsistent states that require a
> reset to continue with anything useful.
Yes. If I got you right, you suggest that we do the reset automatically.
I think it's better to let the user do it, because s/he might want to
do something else before resetting. For example, for the kvm error the
user might want to save the vm state.
For the poweroff case with -no-shutdown it's probably fine, but I don't
want to hard code special cases. It's better and easier to treat them all
as "require system_reset to recover".
- Re: [Qemu-devel] [RFC] Introduce vm_stop_permanent(), (continued)
- Re: [Qemu-devel] [RFC] Introduce vm_stop_permanent(), Blue Swirl, 2011/07/27
- Re: [Qemu-devel] [RFC] Introduce vm_stop_permanent(), Avi Kivity, 2011/07/28
- Re: [Qemu-devel] [RFC] Introduce vm_stop_permanent(), Luiz Capitulino, 2011/07/28
- Re: [Qemu-devel] [RFC] Introduce vm_stop_permanent(), Avi Kivity, 2011/07/28
- Re: [Qemu-devel] [RFC] Introduce vm_stop_permanent(), Jan Kiszka, 2011/07/28
- Re: [Qemu-devel] [RFC] Introduce vm_stop_permanent(), Luiz Capitulino, 2011/07/28
- Re: [Qemu-devel] [RFC] Introduce vm_stop_permanent(), Jan Kiszka, 2011/07/28
- Re: [Qemu-devel] [RFC] Introduce vm_stop_permanent(), Luiz Capitulino, 2011/07/28
- Re: [Qemu-devel] [RFC] Introduce vm_stop_permanent(), Luiz Capitulino, 2011/07/28
- Re: [Qemu-devel] [RFC] Introduce vm_stop_permanent(), Jan Kiszka, 2011/07/28
- Re: [Qemu-devel] [RFC] Introduce vm_stop_permanent(),
Luiz Capitulino <=
- Re: [Qemu-devel] [RFC] Introduce vm_stop_permanent(), Jan Kiszka, 2011/07/28
- Re: [Qemu-devel] [RFC] Introduce vm_stop_permanent(), Luiz Capitulino, 2011/07/28
- Re: [Qemu-devel] [RFC] Introduce vm_stop_permanent(), Alon Levy, 2011/07/28
- Re: [Qemu-devel] [RFC] Introduce vm_stop_permanent(), Blue Swirl, 2011/07/30