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


From: Avi Kivity
Subject: Re: [Qemu-devel] [PATCH 0/2 v3] kvm: notify host when guest panicked
Date: Wed, 21 Mar 2012 18:25:16 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.1) Gecko/20120216 Thunderbird/10.0.1

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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