On Thu, Jul 28, 2011 at 9:22 PM, Luiz Capitulino <lcapitul...@redhat.com> wrote: > 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.
I think the right way to fix this is to disable 'cont' until a system_reset is issued. 'cont' should not perform reset but print an error message about inconsistent state and suggest issuing a 'system_reset'.
