On Sat, 30 Jul 2011 10:41:48 +0300 Blue Swirl <blauwir...@gmail.com> wrote:
> 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'. That's exactly what the series I'm working on does, although the error message is not explicit about issuing a system_reset (will change).
