Re: virtio_net hang

[Emmanuel Lacour <elacour@easter-eggs.com>]

On Thu, Nov 13, 2008 at 03:12:33PM +0000, Mark McLoughlin wrote:
> The fact that re-loading the virtio_net driver fixes things up makes me
> suspect you've found a bug in the virtio_net driver, rather than e.g. a
> bug in the kvm-userspace side.
> 
> To try and narrow down what's happening, when the interface has hung,
> try:
> 
>   - tcpdump on both eth0 in the guest and the tap device on the host 
>     (tap5 in your example)
> 
>   - look for anything unusual in the stats for both those interfaces,
>      e.g. /proc/net/dev, netstat -s etc.
> 
>   - strace the /usr/bin/kvm process
> 
> What you're looking for e.g. is whether a guest->host ping is failing
> because the request packet isn't getting to the host or because the
> reply packet isn't getting to the guest, and where exactly the packet is
> being blocked.
> 

Nice hints, thanks, I will try to debug that deeper and come back with
more informations :)