From mboxrd@z Thu Jan  1 00:00:00 1970
From: Georg Hopp <georg@steffers.org>
Subject: AW: current qemu-kvm doesn't work with vhost
Date: Fri, 17 Jun 2011 22:31:04 +0200
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To: Jan Kiszka <jan.kiszka@web.de>
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In-Reply-To: <4DFB0265.2090305@web.de> (from jan.kiszka@web.de on Fri Jun 17
	09:29:41 2011)
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Am 17.06.2011 09:29:41 schrieb(en) Jan Kiszka:
> On 2011-06-17 09:10, Georg Hopp wrote:
> > Jan Kiszka <jan.kiszka <at> web.de> writes:
> >>
> >> On 2011-06-10 05:08, Amos Kong wrote:
> >>> host kernel: 2.6.39-rc2+
> >>> qemu-kvm : 05f1737582ab6c075476bde931c5eafbc62a9349
> >>>
> >>> (gdb) r -monitor stdio -m 800 ~/RHEL-Server-6.0-64-virtio.qcow2  
> -snapshot
> > -device
> >> virtio-net-pci,netdev=he -netdev tap,vhost=on,id=he
> >>>
> >>
> >> I already came across that symptom in a different context. Fixed  
> by the
> >> patch below.
> >>
> >> However, the real issue is related to an upstream cleanup of the
> >> virtio-pci build. That reveals some unneeded build dependencies in
> >> qemu-kvm. Will post a fix.
> >>
> >> Jan
> >
> > FYI
> >
> > I encountered the same problem and applied the patch.
> >
> > Well this results in the following error while starting the guest:
> >
> >  qemu-system-x86_64: unable to start vhost net: 38:
> >   falling back on userspace virtio
> >
> > and i have no network at all. I will disable vhost=on for now.
> 
> Hmm, works fine for me. The vhost-net module is loaded (though I got a
> different message when I forgot to load it)?
> 
> Jan
> 

Generally it works for me until git revision b2146d8bd.

I have compiled vhost-net directly in my kernel so a have definetly not  
forgotten to load it...
As i use gentoo i made an ebuild that installes exactly this revision.
If i find the time to do some debugging i will do so, but actually i am  
very busy with my job
family and the use of kvm is just a sparetime thing. :D

If it would be of some help i can set a breakpoint just before the path  
and see what
causes the message.

Greetz
    Georg