On 07/22/2012 09:14 PM, Anthony Liguori wrote: > Sasha Levin <levinsasha928@xxxxxxxxx> writes: > >> On 07/21/2012 10:44 AM, 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 >> >> Was the option of implementing a virtio-watchdog driver considered? >> >> You're basically re-implementing a watchdog, a guest-host interface and a set of protocols for guest-host communications. >> >> Why can't we re-use everything we have now, push a virtio watchdog >> driver into drivers/watchdog/, and gain a more complete solution to >> detecting hangs inside the guest. > > The purpose of virtio is not to reinvent every possible type of device. > There are plenty of hardware watchdogs that are very suitable to be used > for this purpose. QEMU implements quite a few already. > > Watchdogs are not performance sensitive so there's no point in using > virtio. The issue here is not performance, but the adding of a brand new guest-host interface. virtio-rng isn't performance sensitive either, yet it was implemented using virtio so there wouldn't be yet another interface to communicate between guest and host. This patch goes ahead to add a "arch pv features" interface using ioports, without any idea what it might be used for beyond this watchdog. -- 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
