At 10/31/2012 09:12 AM, Marcelo Tosatti Wrote: > On Thu, Oct 25, 2012 at 11:42:32AM +0800, Hu Tao 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 > > It has been asked earlier why a simple virtio device is not usable > for this (with no response IIRC). 1. We can't use virtio device when the kernel is booting. 2. The virtio's driver can be built as a module, and if it is not loaded and the kernel is panicked, there is no way to notify the host. 3. I/O port is more reliable than virtio device. If virtio's driver has some bug, and it cause kernel panicked, we can't use it. The I/O port is more reliable because it only depends on notifier chain(If we use virtio device, it also depends on notifier chain). Thanks Wen Congyang > > Also, there is no high level documentation: purpose of the interface, > how a management application should use it, etc. > > -- 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
