On Tue, Aug 14, 2012 at 01:53:01PM -0500, Anthony Liguori wrote: > Marcelo Tosatti <mtosatti@xxxxxxxxxx> writes: > > > On Tue, Aug 14, 2012 at 05:55:54PM +0300, Yan Vugenfirer wrote: > >> > >> On Aug 14, 2012, at 1:42 PM, Jan Kiszka wrote: > >> > >> > On 2012-08-14 10:56, Daniel P. Berrange wrote: > >> >> On Mon, Aug 13, 2012 at 03:21:32PM -0300, Marcelo Tosatti wrote: > >> >>> On Wed, Aug 08, 2012 at 10:43:01AM +0800, Wen Congyang wrote: > >> >>>> We can know the guest is panicked when the guest runs on xen. > >> >>>> But we do not have such feature on kvm. > >> >>>> > >> >>>> Another purpose of this feature is: management app(for example: > >> >>>> libvirt) can do auto dump when the guest is panicked. If management > >> >>>> app does not do auto dump, the guest's user can do dump by hand if > >> >>>> he sees the guest is panicked. > >> >>>> > >> >>>> We have three solutions to implement this feature: > >> >>>> 1. use vmcall > >> >>>> 2. use I/O port > >> >>>> 3. use virtio-serial. > >> >>>> > >> >>>> We have decided to avoid touching hypervisor. The reason why I choose > >> >>>> choose the I/O port is: > >> >>>> 1. it is easier to implememt > >> >>>> 2. it does not depend any virtual device > >> >>>> 3. it can work when starting the kernel > >> >>> > >> >>> How about searching for the "Kernel panic - not syncing" string > >> >>> in the guests serial output? Say libvirtd could take an action upon > >> >>> that? > >> >> > >> >> No, this is not satisfactory. It depends on the guest OS being > >> >> configured to use the serial port for console output which we > >> >> cannot mandate, since it may well be required for other purposes. > >> > > >> Please don't forget Windows guests, there is no console and no "Kernel Panic" string ;) > >> > >> What I used for debugging purposes on Windows guest is to register a bugcheck callback in virtio-net driver and write 1 to VIRTIO_PCI_ISR register. > >> > >> Yan. > > > > Considering whether a "panic-device" should cover other OSes is also \ > > something to consider. Even for Linux, is "panic" the only case which > > should be reported via the mechanism? What about oopses without panic? > > > > Is the mechanism general enough for supporting new events, etc. > > Hi, > > I think this discussion is gone of the deep end. > > Forget about !x86 platforms. They have their own way to do this sort of > thing. The panic function in kernel/panic.c has the following options, which appear to be arch independent, on panic: - reboot - blink None are paravirtual interfaces however. > Think of this feature like a status LED on a motherboard. These > are very common and usually controlled by IO ports. > > We're simply reserving a "status LED" for the guest to indicate that it > has paniced. Let's not over engineer this. My concern is that you end up with state that is dependant on x86. Subject: [PATCH v8 3/6] add a new runstate: RUN_STATE_GUEST_PANICKED Having the ability to stop/restart the guest (and even introducing a new VM runstate) is more than a status LED analogy. Can this new infrastructure be used by other architectures? Do you consider allowing support for Windows as overengineering? > Regards, > > Anthony Liguori > > > > >> > >> > Well, we have more than a single serial port, even when leaving > >> > virtio-serial aside... > >> > > >> > Jan > >> > > >> > -- > >> > Siemens AG, Corporate Technology, CT RTC ITP SDP-DE > >> > Corporate Competence Center Embedded Linux > >> > -- > >> > To unsubscribe from this list: send the line "unsubscribe kvm" in > >> > the body of a message to majordomo@xxxxxxxxxxxxxxx > >> > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
