Re: [PATCH 0/2] Introduce panic hypercall

Anthony Liguori
2011-06-20T19:28:50Z

On 06/20/2011 10:31 AM, Avi Kivity wrote:
> On 06/20/2011 04:38 PM, Daniel Gollub wrote:
>> Introduce panic hypercall to enable the crashing guest to notify the
>> host. This enables the host to run some actions as soon a guest
>> crashed (kernel panic).
>>
>> This patch series introduces the panic hypercall at the host end.
>> As well as the hypercall for KVM paravirtuliazed Linux guests, by
>> registering the hypercall to the panic_notifier_list.
>>
>> The basic idea is to create KVM crashdump automatically as soon the
>> guest paniced and power-cycle the VM (e.g. libvirt<on_crash />).
>
> This would be more easily done via a "panic device" (I/O port or
> memory-mapped address) that the guest hits. It would be intercepted by
> qemu without any new code in kvm.\
>
> However, I'm not sure I see the gain. Most enterprisey guests already
> contain in-guest crash dumpers which provide more information than a
> qemu memory dump could, since they know exact load addresses etc. and
> are integrated with crash analysis tools. What do you have in mind?

FYI, s390 has this functionality. It's useful because there's no use in
having a guest just spin in a panic loop. Crash dump integration is
much more complicated and requires functioning networking or some
paravirt channel.

Regards,

Anthony Liguori