From: folkert <folkert@vanheusden.com>
To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: kvm <kvm@vger.kernel.org>
Subject: Re: FAQ on linux-kvm.org has broken link
Date: Mon, 5 Aug 2013 22:59:45 +0200 [thread overview]
Message-ID: <20130805205944.GP8801@belle.intranet.vanheusden.com> (raw)
In-Reply-To: <20130805113154.GD14592@stefanha-thinkpad.muc.redhat.com>
> If you do find something in dmesg that could be very helpful.
Ok it is down again: nothing in dmesg, neither on the guest or in the
host.
> Based on this information it seems like a bug in the virtio_net guest
> driver or vhost_net on the host. Actually there is one contradictory
> piece of evidence: in the original bug report you said "using e1000
> instead of virtio: did not help". Can you confirm that e1000 also does
> not work?
When I tested it, it also did not work yes.
> In your original bug report you said "If I then ping any host connected
> to that interface, no ping comes back: only a message about buffer space
> not being enough". Can you post the exact error message and whether it
> is printed by ping inside the guest, dmesg inside the guest, or dmesg on
> the host?
It was inside the guest going to the outside world (eg outside of the
host).
> There is still the possibility that there is a networking configuration
> issue or bug inside the guest itself. That would explain why this has
> happened across different configurations (tap, mactvap, vhost_net,
> e1000).
I don't think it is as:
- bringing down the interfaces _AND_ doing rmmod/modprobe of virtio_net
solves it
- it also happened twice on an other guest
> Two approaches to get closer to the source of the problem:
> 1. Try the latest vanilla kernel on the host (Linux 3.10.5). This way
> you can rule out fixed bugs in vhost_net or tap.
> 2. Get the system into the bad state and then do some deeper. Start
> with outgoing ping, instrument guest driver and host vhost_net
> functions to see what the drivers are doing, inspect the transmit
> vring, etc.
>
> #1 is probably the best next step. If it fails and you still have time
> to work on a solution we can start digging deeper with #2.
I can upgrade now to 3.10.3 as that is the current version in debian.
Folkert van Heusden
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next prev parent reply other threads:[~2013-08-05 20:59 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-30 1:18 FAQ on linux-kvm.org has broken link folkert
2013-07-30 12:25 ` Stefan Hajnoczi
2013-07-30 12:45 ` folkert
2013-07-30 20:45 ` folkert
2013-07-31 8:46 ` Stefan Hajnoczi
2013-08-02 11:37 ` folkert
2013-08-02 15:25 ` Stefan Hajnoczi
2013-08-02 18:06 ` folkert
2013-08-05 11:31 ` Stefan Hajnoczi
2013-08-05 20:59 ` folkert [this message]
2013-08-06 8:13 ` Stefan Hajnoczi
2013-09-03 17:03 ` folkert
2013-08-26 19:50 ` folkert
2013-08-27 7:31 ` Stefan Hajnoczi
2013-10-29 17:18 ` folkert
2013-11-01 9:52 ` Stefan Hajnoczi
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