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Message-ID: <20120229100550.GF24600@redhat.com>
Date: Wed, 29 Feb 2012 12:05:50 +0200
From: Gleb Natapov <gleb@...hat.com>
To: Avi Kivity <avi@...hat.com>
Cc: Wen Congyang <wency@...fujitsu.com>,
kvm list <kvm@...r.kernel.org>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
"Daniel P. Berrange" <berrange@...hat.com>,
linux-kernel@...r.kernel.org, qemu-devel <qemu-devel@...gnu.org>
Subject: Re: [PATCH] kvm: notify host when guest paniced
On Wed, Feb 29, 2012 at 12:00:41PM +0200, Avi Kivity wrote:
> On 02/29/2012 11:55 AM, Gleb Natapov wrote:
> > > >
> > >
> > > How about using a virtio-serial channel for this? You can transfer any
> > > amount of information (including the dump itself).
> > >
> > Isn't it unreliable after the guest panicked?
>
> So is calling hypercalls, or dumping, or writing to the screen. Of
> course calling a hypercall is simpler and so is more reliable.
>
Yes, crash can be so severe that it is not even detected by a kernel
itself, so not OOPS message even printed. But in most cases if kernel is
functional enough to print OOPS it is functional enough to call single
hypercall instruction.
> > Having special kdump
> > kernel that transfers dump to a host via virtio-serial channel though
> > sounds interesting. May be that's what you mean.
>
> Yes. The "panic, starting dump" signal should be initiated by the
> panicking kernel though, in case the dump fails.
>
Then panic hypercall sounds like a reasonable solution.
--
Gleb.
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