[Pkg-xen-devel] Bug#702428: Bug#702428: HVM networking tap/vif bug (Debian bug 702428)

[Daniel Pocock]

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On 17/03/13 18:49, Ian Campbell wrote:
> On Sun, 2013-03-17 at 18:44 +0100, Daniel Pocock wrote:
>> 
>> On 17/03/13 18:38, Ian Campbell wrote:
>>> I'm afraid I don't know about the issue you are seeing but I
>>> can comment on one part:
>>> 
>>> On Sun, 2013-03-17 at 15:02 +0100, Daniel Pocock wrote:
>>>> while the output from dmesg suggests that the interface
>>>> vif10.0 was created.  It appears there is confusion between
>>>> the vifX.Y and tapX.Y naming schemes.
>>> 
>>> An HVM guest with a network device should get *both* vifX.Y
>>> and tapX.Y, they are kind of two faces of the same "device".
>>> The tapX.Y is the emulated NIC (rtl8169 or e1000 or something)
>>> while the vifX.Y is the PV NIC which the guest can choose to
>>> switch over too (for increased perf etc) if it has a suitable
>>> driver (e.g. Linux PVHVM support, PV drivers for Windows etc
>>> etc).
>>> 
>>> As to why tapX.Y cannot be added to a bridge, I've no idea,
>>> sorry. Are you using bridge or vswitch? Can you manually
>>> enslave the tap device to the bridge?
>>> 
>> I'm using Open vSwitch
> 
> I wonder if something might be logged by ovs about why it is
> refusing this operation? I think OVS has pretty extensive logging
> capabilities too so you might be able to increase the verbosity.
> 

Ok, I played with it some more, there is definite progress but I still
believe something is wrong in one of the scripts:

I notice this in syslog:

 domid: 19
 -c config qemu network with xen bridge for
 tap19.0 xapi1
 can't add tap19.0 to bridge xapi1: Operation not supported
 /etc/xen/scripts/qemu-ifup: could not launch network script
 Could not initialize device 'tap'


After seeing that, I decided to look inside the script mentioned
there, /etc/xen/scripts/qemu-ifup

I found the brctl command in the script

    brctl addif $2 $1


Commented out that line so the script now returns 0 (success)

Booted the VM - it boots successfully, but without network
connectivity.  It has a VIF, but no ping

Looking at `brctl show xapi1' and I see vif20.0 is in there, but
tap20.0 is not

Manually run the command

    ovs-vsctl add-port xapi1 tap20.0

Now it is possible to ping the running HVM domU

Should the script be using the ovs-vsctl command instead of brctl?  Or
have I misconfigured something and the wrong script is being run?

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