[Qemu-devel] Re: [PATCH 0/8] vlan cleanup

[Jan Kiszka <jan.kiszka@siemens.com>]

Miguel Di Ciurcio Filho wrote:
> On Tue, Jul 13, 2010 at 3:16 AM, Jan Kiszka <jan.kiszka@web.de> wrote:
>> Miguel Di Ciurcio Filho wrote:
>>> This series removes the vlan stuff without mercy. I've tried to make the steps
>>> as small as possible, but the last one is huge. I did some basic tests and
>>> networking is still working, so reviews are welcome :-D
>> Sorry, this is a bit too rude. This not only removes the vlan model,
>> something one may talk about, but also the innocent socket back-ends and
>> the useful pcap dump support.
>>
>> Socket back-ends allow quick and easy unprivileged inter-VM network
>> setups. Nothing for production systems, but useful for testing purposes
>> on boxes where taps are not allowed or unhandy to configure.
>>
> 
> I agree that it might be handy sometimes, but one could use VDE for
> that too. Runs on user-space and can be tunneled over SSH or netcat
> [1].

Yes, I know. But it requires yet another process as hop. In contrast,
peer-to-peer sockets used to be as fast as taps in certain setup (now
taps became faster again).

> Another option would be to make the socket backend properly work as a
> netdev, so one could directly connect guest NICs on different hosts,
> but on a 1:1 relationship.

What is required for this conversion? And are VDE and Slirp already
fully converted?

> 
>> The dump client helps to debug user mode guest networks, namely slirp
>> which you did not remove. If that should become the only use case for
>> vlans with more than 2 nodes, we could think about making it a special
>> feature of backend devices.
>>
> 
> socket and dump are only used when the vlan backends are concerned, so
> they don't have any useful meaning outside of that.

That's still the default network configuration unless you configure
something specific (management tools do, of course).

> 
> How about add dump hooks on backends? I don't think network backends
> need to be stackable like block devices, thought.

That's what I suggested. Definitely an option to migrate the dump feature.

> 
>> I'm open for cleanups here, but they do require a bit mercy - and should
>> also mention the reason.
>>
> 
> Well, basically there is a lot of "if (vlan) else if (peer)". While
> discussing the query-netdev QMP command, no one has shown any love
> about the vlan stuff at all, quite the contrary and it was kept out of
> the protocol.

As I said: Removing the vlan abstraction is one thing, removing backends
is another. I would suggest to start with preparatory work (enable all
backends for netdev, port dump, make netdev default), then remove the
vlan infrastructure.

Jan

> 
> Regards,
> 
> Miguel
> 
> [1] http://wiki.virtualsquare.org/index.php/VDE#vde_plug

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