[systemd-devel] systemd-networkd: setting the MAC address for a .netdev unit?

[Tom Gundersen]

Hi Matthias,

On Fri, Apr 18, 2014 at 1:08 AM, Matthias Schiffer
<mschiffer at universe-factory.net> wrote:
> On 04/18/2014 12:14 AM, Matthias Schiffer wrote:
>> On 04/17/2014 11:28 PM, Dave Reisner wrote:
>>> On Thu, Apr 17, 2014 at 11:02:11PM +0200, Matthias Schiffer wrote:
>>>> Hi,
>>>> I'd like to configure the MAC address of a bridge device statically (as
>>>> bridges tend to change their MAC address depending on the order the
>>>> ports are added on Linux otherwise), but there doesn't seem to be a way
>>>> to match for a bridge in a .link unit. This would be very useful for
>>>> macvlans as well.
>>>
>>> Link files can match bridges generally with Type=bridge or Driver=bridge
>>> in the [Match] section, or more specifically by just matching on name.
>>> In the [Link] section, MACAddressPolicy=persistent should give you
>>> persistent hw addresses in the general case, or you can use
>>> MACAddress=fe:ed:fa:ce:be:ef to set whatever you like for more specific
>>> matches.
>>>
>>> Does this not work for you?
>> Hmm, I thought I tried that before, but using
>> MACAddress=fe:ed:fa:ce:be:ef seems to work now. Please note that the
>> Name= match is not documented in the systemd.link manpage.
>
> I have to correct myself: The Name= match does not exist for .link
> units. My testcase just seemed to work as a [Match] section only
> consisting of a Name= match was considered an empty [Match] section and
> matched on all devices...
>
> This should really be added as AFAICT there is currently no way to match
> on virtual devices like briges, TAP devices, batman-adv devices, etc...
> which have neither a persistent MAC address nor an ID_PATH to match on.

So I think what we should do here is to allow MAC address (and other
things) to be set when creating the netdevs. I made an attempt at this
by generating a "predictable" one based on the interface name and the
machine-id. Would that do it for you, or are you after a _specific_
mac address, rather than just one that is always the same? I had to
revert the code doing this for now as there was a kernel bug, however
we'll hopefully get that sorted soon and then get back to this.

Cheers,

Tom