Re: [PATCH 0/2 v3] kvm: notify host when guest panicked

[Avi Kivity]

On 03/21/2012 06:18 PM, Corey Minyard wrote:
>
>> 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.
>
> I doubt that's the best example, unfortunately.  The IPMI event log
> has limited space and it has to be send a little piece at a time since
> each log entry is 14 bytes.  It just prints the panic string, nothing
> else.  Not that it isn't useful, it has saved my butt before.
>
> You have lots of interesting options with paravirtualization.  You
> could, for instance, create a console driver that delivered all
> console output efficiently through a hypercall.  That would be really
> easy.  Or, as you mention, a custom way to deliver panic information. 
> Collecting information like stack traces would be harder to
> accomplish, as I don't think there is currently a way to get it except
> by sending it to printk.

That already exists; virtio-console (or serial console emulation) can do
the job.

In fact the feature can be implemented 100% host side by searching for a
panic string signature in the console logs.

-- 
error compiling committee.c: too many arguments to function

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