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

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Date:	Tue, 13 Mar 2012 12:47:27 +0200
From:	Avi Kivity <avi@...hat.com>
To:	"Daniel P. Berrange" <berrange@...hat.com>
CC:	Wen Congyang <wency@...fujitsu.com>,
	kvm list <kvm@...r.kernel.org>,
	qemu-devel <qemu-devel@...gnu.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Jan Kiszka <jan.kiszka@...mens.com>,
	Gleb Natapov <gleb@...hat.com>
Subject: Re: [PATCH 0/2 v3] kvm: notify host when guest panicked

On 03/13/2012 11:18 AM, Daniel P. Berrange wrote:
> On Mon, Mar 12, 2012 at 12:33:33PM +0200, Avi Kivity wrote:
> > On 03/12/2012 11:04 AM, Wen Congyang wrote:
> > > Do you have any other comments about this patch?
> > >
> > 
> > Not really, but I'm not 100% convinced the patch is worthwhile.  It's
> > likely to only be used by Linux, which has kexec facilities, and you can
> > put talk to management via virtio-serial and describe the crash in more
> > details than a simple hypercall.
>
> As mentioned before, I don't think virtio-serial is a good fit for this.
> We want something that is simple & guaranteed always available. Using
> virtio-serial requires significant setup work on both the host and guest.

So what?  It needs to be done anyway for the guest agent.

> Many management application won't know to make a vioserial device available
> to all guests they create. 

Then they won't know to deal with the panic event either.

> Most administrators won't even configure kexec,
> let alone virtio serial on top of it. 

It should be done by the OS vendor, not the individual admin.

> The hypercall requires zero host
> side config, and zero guest side config, which IMHO is what we need for
> this feature.

If it was this one feature, yes.  But we keep getting more and more
features like that and we bloat the hypervisor.  There's a reason we
have a host-to-guest channel, we should use it.

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

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