At 03/21/2012 05:11 PM, Gleb Natapov Wrote: > On Wed, Mar 21, 2012 at 08:56:03AM +0800, Wen Congyang wrote: >> At 03/20/2012 11:45 PM, Gleb Natapov Wrote: >>> On Tue, Mar 20, 2012 at 05:59:16PM +0800, Wen Congyang wrote: >>>> At 03/19/2012 03:33 PM, Wen Congyang Wrote: >>>>> At 03/08/2012 03:57 PM, Wen Congyang Wrote: >>>>>> We can know the guest is paniced 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 crashed. If management >>>>>> app does not do auto dump, the guest's user can do dump by hand if >>>>>> he sees the guest is paniced. >>>>>> >>>>>> I touch the hypervisor instead of using virtio-serial, because >>>>>> 1. it is simple >>>>>> 2. the virtio-serial is an optional device, and the guest may >>>>>> not have such device. >>>>>> >>>>>> Changes from v2 to v3: >>>>>> 1. correct spelling >>>>>> >>>>>> Changes from v1 to v2: >>>>>> 1. split up host and guest-side changes >>>>>> 2. introduce new request flag to avoid changing return values. >>>>>> -- >>>>>> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in >>>>>> the body of a message to majordomo@xxxxxxxxxxxxxxx >>>>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>>>>> Please read the FAQ at http://www.tux.org/lkml/ >>>>>> >>>>> >>>>> >>>>> Hi all: >>>>> >>>>> we neet this feature, but we don't decide how to implement it. >>>>> We have two solution: >>>>> 1. use vmcall >>>>> 2. use virtio-serial. >>>>> >>>>> I will not change this patch set before we decide how to do it. >>>>> Can we make a decision recent days? >>>> >>>> Anybody can decide which solution to use? >>>> >>> To make an informed decision we need to have at least raw idea how >>> virtio-serial variant will look. >> >> Hmm, I think we can do this: >> 1. reset the virtio-serial device or reset the port we use to notice >> the host that guest is panicked. >> 2. write some specific messages to the port >> >> So the port should have fixed name. If this port is opened by the userspace >> before the guest is paniced, I am not sure whether we can use it(because a >> port only can be opened once at the same time). > Yes, IMO we should dedicate one virtio-serial port for panic > notifications. Just like we dedicate one for a console. > >> We cannot call any function in the module, so we may need to write a simple >> driver for virtio-serial(like diskdump's disk driver). >> > netconsole uses standard NIC drivers in polling mode to send OOPSes > over the network and it mostly works. So I think using virtio-serial > driver is not out of question, but with IRQ disabled of course. The code for netconsole is in which file? Another question: we cannot call the function in the module directly in the kernel. > >> I donot know how to implement it now. But I guess that it may be complicated. >> > Look at drivers/char/ipmi/ipmi_msghandler.c. It has code to send panic > event over IMPI. The code is pretty complex. Of course if we a going to > implement something more complex than simple hypercall for panic > notification we better do something more interesting with it than just > saying "panic happened", like sending stack traces on all cpus for > instance. If we implement it by virtio-serial, I agree with passing more useful message to host. Thanks Wen Congyang > > -- > Gleb. > -- 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
