Re: [Xen-devel] Restore PVHVM DomU with a different MAC

[Kangjie Xi <imxikangjie@xxxxxxxxx>]

2017-09-13 17:24 GMT+08:00 Wei Liu <wei.liu2@xxxxxxxxxx>:
> On Wed, Sep 13, 2017 at 04:25:17PM +0800, Kangjie Xi wrote:
>> Hi,
>>
>> I created a Ubuntu-17.04-x64 PVHVM DomU, so I can use "xl
>> network-attach/detach" to add/delete network interfaces, it works
>> well.
>>
>> However I wanted to restore the DomU with a different MAC address, so
>> before saving the checkpoit file, I deleted the network interface with
>> "xl netwrok-detach", and assigned a different MAC in the configuration
>> file and restored the DomU:
>>
>> # xl network-detach ubuntu 0
>> # xl save ubuntu ubuntu.checkpoint
>> # xl restore ubuntu.cfg ubuntu.checkpoint
>>
>
> Doing this causes xl to ignore the saved state and use the provided
> config file to construct the new guest iirc. I haven't checked the code
> in detail though.
>
> The end result seems to be what you wanted.
>
>>  But the DomU didn't detect the new network interface. In Dom0, could
>> see the DomU has new MAC.
>>
>> # xl network-list ubuntu
>> Idx BE Mac Addr.         handle state evt-ch   tx-/rx-ring-ref BE-path
>> 0   0  00:16:3e:eb:ca:67     0     1     -1    -1/-1
>> /local/domain/0/backend/vif/139/0
>>
>
> A vif is created but DomU can't find it. It is possible DomU kernel
> doesn't go through the whole cycle of device probing and simply ignores
> a vif that it doesn't know about during restore. As far as it is
> concerned, the vif originally provided is already gone. The new vif
> shows up out of nowhere.
>
> You may be able to manually generate a udev event to make the kernel
> probe the new vif. I don't know.
>
>> If I add network interface manually after restoring, the DomU can
>> detect new network interface automatically.
>>
>> # xl network-attach ubuntu type=vif mac=00:16:3e:eb:ca:68 bridge=virbr0
>>
>> # xl network-list ubuntu
>> Idx BE Mac Addr.         handle state evt-ch   tx-/rx-ring-ref BE-path
>> 0   0  00:16:3e:eb:ca:67     0     1     -1    -1/-1
>> /local/domain/0/backend/vif/139/0
>> 1   0  00:16:3e:eb:ca:68     1     4     -1   529/528
>> /local/domain/0/backend/vif/139/1
>>
>> Is it a bug?
>>
>
> Can't say for sure at this stage.

Windows with PV drivers DomU can restore with a new MAC address.

# xl network-detach windows 0
# xl save windows windows.checkpoint
# xl restore windows.cfg windows.checkpoint

After restoring, the Windows DomU can detect the new network interface
automatically.

>
>> Thanks
>>
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>> Xen-devel@xxxxxxxxxxxxx
>> https://lists.xen.org/xen-devel

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