Re: [virtio-dev] [RFC PATCH net-next v2 1/2] virtio_net: Introduce VIRTIO_NET_F_BACKUP feature bit

[Alexander Duyck <alexander.duyck@gmail.com>]

On Mon, Jan 22, 2018 at 6:04 PM, Michael S. Tsirkin <mst@redhat.com> wrote:
> On Mon, Jan 22, 2018 at 05:34:37PM -0800, Samudrala, Sridhar wrote:
>> On 1/22/2018 4:05 PM, Michael S. Tsirkin wrote:
>> > On Mon, Jan 22, 2018 at 03:27:40PM -0800, Samudrala, Sridhar wrote:
>> > > > > You could probably
>> > > > > even handle the Tx queue selection via a simple eBPF program and map
>> > > > > since the input for whatever is used to select Tx should be pretty
>> > > > > simple, destination MAC, source NUMA node, etc, and the data-set
>> > > > > shouldn't be too large.
>> > > > That sounds interesting. A separate device might make this kind of setup
>> > > > a bit easier.  Sridhar, did you look into creating a separate device for
>> > > > the virtual bond device at all?  It does not have to be in a separate
>> > > > module, that kind of refactoring can come later, but once we commit to
>> > > > using the same single device as virtio, we can't change that.
>> > > No. I haven't looked into creating a separate device. If we are going to
>> > > create a new
>> > > device, i guess it has to be of a new device type with its own driver.
>> > Well not necessarily - just a separate netdev ops.
>> > Kind of like e.g. vlans share a driver with the main driver.
>>
>> Not sure what you meant by vlans sharing a driver with the main driver.
>> IIUC, vlans are supported via 802.1q driver and  creates a netdev of type
>> 'vlan'
>> with vlan_netdev_ops
>
> But nothing prevents a single module from registering
> multiple ops.

Just to clarify, it seems like what you are suggesting is just adding
the "master" as a separate set of netdev ops or netdevice and to have
virtio spawn two network devices, one slave and one master, if the
BACKUP bit is set. Do I have that right?

I am good with the code still living in the virtio driver and
consolidation with other similar implementations and further
improvement could probably happen later as part of some refactor.

Thanks.

- Alex