[libvirt] RFC: setting mac address on network devices being assigned to a guest via PCI passthrough (<hostdev>)

[Paolo Bonzini]

On 01/23/2012 05:12 PM, Laine Stump wrote:
>>
>> In view of the discussion on SCSI passthrough, it seems to me that
>> this should be attached to an <interface> element:
>>
>> <devices>
>> <interface type='hostdev'>
>> <source>
>> <address type='pci' bus='0x06' slot='0x02' function='0x0'/>
>> </source>
>> <mac address='00:16:3e:5d:c7:9e'/>
>> <address type='pci' .../>
>> </interface>
>> </devices>
>
> Nice! I should have thought of this in my original proposal - it's the
> logical extension of having networks of type='hostdev'. I would prefer
> this as well, but it hits one of Dan's criticism's of the original
> proposal (from
> https://www.redhat.com/archives/libvir-list/2011-August/msg01033.html ),
> so I didn't further consider using a change to <interface>:

I didn't have time now to read the whole original discussion, however...

> On 08/22/2011 at 05:17 AM, Dan Berrange wrote:
>>  The issue I see is that if an application wants to know what
>>  PCI devices have been assigned to a guest, they can no longer
>>  just look at<hostdev>  elements. They also need to look at
>> <interface>  elements. If we follow this proposed model in other
>>  areas, we could end up with PCI devices appearing as<disks>
>> <controllers>  and who knows what else.

... this is exactly what we're doing for <controller>.  In that case, 
the <source> syntax is roughly the same that you use in a SCSI pool.

See here for how it arose:

http://www.redhat.com/archives/libvir-list/2011-October/msg01298.html

> Since originally proposing the <hostdev> examples for network
> cards, I've switched to the opinion that this was in fact the
> wrong thing todo at all. The network devices should be in the
> <interface> element, so we have access to all the properties
> that this element allows for.
>
> My general view is that <hostdev> should be kept for "opaque"
> device assignment where we're not caring about what capabilities
> the device has. Just "blind" assignment of the PCI/USB/ISA
> hardware device based on their hardware addresses.

(That's Dan speaking, not me :)).

Paolo