Re: [Qemu-devel] Intermittent e1000 failure on qemu-kvm 1.0

[Chris Webb <chris@arachsys.com>]

Stefan Hajnoczi <stefanha@gmail.com> writes:

> On Mon, Apr 02, 2012 at 04:37:23PM +0100, Chris Webb wrote:
> > We initially saw a problem after an upgrade from 0.15.x to 1.0.
> 
> Perhaps git-bisect(1) can help you track down the change that introduced
> this between 0.15 and 1.0.

Hi. I attempted this, but the bug is so intermittent and there are so many
unrelated red-herring breakages along the branchy path between the two that
I had to abandon the effort after a week I'm afraid. It's phenomenally time
consuming, unlike any other bug I've tried to bisect.

> It sounds like this is not the issue, but are you sure the bridge has
> forwarding delay set to 0 or Spanning Tree Protocol disabled?  With STP
> enabled no traffic will be forwarded by the bridge for a configured
> timeout, and depending on the timing of your VM bootup you could see
> weird things.  You can check with brctl showstp br0.

No STP enabled, but the networking is permanently broken on these guests in
any case, not just slow to get started. Usually they've been sat there for
half an hour or more by the time I get back to the stopped reboot loop, and
I left one broken over a weekend without it fixing itself. The network is
statically configured, so if it were down temporarily and came back, pings
would then start working fine.

Cheers,

Chris.