Re: [Xen-devel] Xen 4.1.2 PVHVM guest with Linux 3.1.0 network problem, empty MAC address (all zeroes)

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Mon, Oct 31, 2011 at 10:13:36PM +0200, Pasi Kärkkäinen wrote:
> Hello,
> 
> While testing Fedora 16 Xen PVHVM guests I noticed the following problem:
> 
> When starting F16 PVHVM guest I can see the vifX.0 and tapX.0 interfaces 
> appear on dom0, 
> but after the guest kernel (Linux 3.1.0) starts and loads PVHVM drivers the 
> vif/tap interfaces disappear from dom0.. 
> so the bridge in dom0 doesn't have any vifs/taps connected to it anymore.
> 
> Has anyone seen that behaviour? 
> 
> I bet that's also the reason why eth0 inside the PVHVM guest 
> has a MAC address with only zeroes in it: 00:00:00:00:00:00.
> 
> If I disable PVHVM with "xen_platform_pci=0" in the domain cfgfile
> then network for the guest works OK using the qemu-dm emulated nic.
> 
> PVHVM guest cfgfile:
> 

<snip>

> 
> Some output from inside the PVHVM guest:
> 
> # ifconfig eth0
> eth0      Link encap:Ethernet  HWaddr 00:00:00:00:00:00
>           BROADCAST MULTICAST  MTU:1500  Metric:1
>           RX packets:0 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
>           collisions:0 txqueuelen:1000
>           RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)
> 

<snip>

> 
> Full PVHVM guest kernel (Linux 3.1.0) dmesg attached to this email.
> Some parts of the guest dmesg here:
> 
> $ egrep -i 'xen|vif' xen-4.1.2-f16pvhvm-linux-3.1.0-dmesg.txt
> 

<snip>

> 
> dom0 kernel (Linux 3.1.0 aswell) messages:
> 

<snip>

> 
> 
> "xm log" doesn't have any errors.
> Any ideas how to fix this? Why do the vif/tap devices disappear from dom0?
> 

Well.. it was actually as simple as removing "type=ioemu" from the vif line.
Working vif-example for Xen PVHVM Linux guest VM:

vif = [ 'mac=00:16:5f:03:01:15, bridge=virbr0, model=e1000' ]

So uhm.. when enabling PVHVM there's no need to modify the disk line, 
but you need to modify the vif-line.. is that like it should be ?


-- Pasi


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