Re: [Qemu-devel] [QEMU] net: adapt dump to support the new syntax

[Zhi Yong Wu]

On Sat, Feb 18, 2012 at 5:48 PM, Stefan Hajnoczi <address@hidden> wrote:
> On Sat, Feb 18, 2012 at 8:57 AM, Zhi Yong Wu <address@hidden> wrote:
>> On Fri, Feb 17, 2012 at 6:55 PM, Stefan Hajnoczi <address@hidden> wrote:
>>> On Fri, Feb 17, 2012 at 6:54 AM, Zhi Yong Wu <address@hidden> wrote:
>>>> I would like to know if some one is playing around with the patchset.
>>>>
>>>> If yes, can any one make one response? I am very interested in rebasing
>>>> it, and then playing with it.
>>>
>>> AFAIK no one is working on it - the main thing that is missing here is
>>> tests so that we don't break the existing "VLAN" feature and
>>> command-line interface.
>> If you are available, can you let us know what their difference among
>> -net, -netdev and hub? their drawback? their advantage? thanks
>
> -net is the old command-line option for defining both guest network
> devices (e.g. e1000, virtio-net) and also host network devices (e.g.
> tap, socket, user).  It uses the VLAN concept and does not use "peer"
> IIRC.
>
> -netdev/-device is the new way to specify networking.  You use -netdev
> to define host network devices (e.g. tap, socket, user).  You use
> -device to specify guest network devices (e.g. e1000, virtio-net-pci).
>  This approach does not use the "VLAN" feature and instead uses
> ->peer.  That means nic->per == netdev and netdev->peer == nic.
>
> There is a performance improvement with -netdev/-device because we do
> not use "VLAN" forwarding in the network subsystem and I think it
> enables tap offloads (checksum offload, GRO, TSO) but I don't remember
> the detalis there.
>
> The "hub" is the same as QEMU "VLANs" except it removes all the
> special case code in the network subsystem and instead implements the
> functionality in a normal NetClientState.  Now the hub is no longer
> part of the network subsystem, its just a net device in QEMU.
>
> The critical thing when transitioning to the hub device is that the
> old "VLAN" command-line options must continue to work!  Users should
> see no difference from before.  But internally the net subsystem will
> only deal with NetClientState instead of VLANClientState plus
> VLANState.  Everything will use ->peer.
Nice, thanks.

>
> Stefan



-- 
Regards,

Zhi Yong Wu