On Thu, 28 Jul 2011 20:04:58 +0200 Jan Kiszka <jan.kis...@web.de> wrote:
> On 2011-07-28 20:00, Luiz Capitulino wrote: > > On Thu, 28 Jul 2011 19:52:31 +0200 > > Jan Kiszka <jan.kis...@web.de> wrote: > > > >> On 2011-07-28 19:48, Luiz Capitulino wrote: > >>> On Thu, 28 Jul 2011 14:39:23 -0300 > >>> Luiz Capitulino <lcapitul...@redhat.com> wrote: > >>> > >>>> On Thu, 28 Jul 2011 17:20:41 +0200 > >>>> Jan Kiszka <jan.kis...@web.de> wrote: > >>>> > >>>>> On 2011-07-28 17:18, Luiz Capitulino wrote: > >>>>>> On Thu, 28 Jul 2011 16:19:19 +0200 > >>>>>> Jan Kiszka <jan.kis...@web.de> 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<a...@redhat.com> wrote: > >>>>>>>>> > >>>>>>>>>> On 07/28/2011 12:44 AM, Blue Swirl wrote: > >>>>>>>>>> > On Wed, Jul 27, 2011 at 9:42 PM, Luiz > >>>>>>>>> Capitulino<lcapitul...@redhat.com> 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. > > Associating the reset with a cont means requesting an explicit action > from the user. I'm not suggesting to do the reset when the stop state is > entered. I see. But automatically resetting on cont might be unexpected to the user, even on a bad state. Another option would be to add a force option to cont, where the reset is done when the state is invalid (otherwise cont will return an error). I still prefer to let the user do it manually though. > > 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". > > In any case, we need to tag the current state as stopped-and-invalid or > so vs. a normal stop. That remains a valuable first step. How to deal > with that information is the second one.
