Re: [RFC PATCH 2/6] qapi: net: add socket-ng netdev

[Laurent Vivier]

On 10/05/2022 23:24, Stefano Brivio wrote:
...
> I don't know if this is an issue, but I couldn't figure out the reason
> for this difference either:
>
> - with the old socket option, I can pass something like:
>
>      -net socket,fd=5 -net nic,model=virtio
>
>    and frames are sent to/received from socket number 5 (which I
>    pre-opened)
>
> - with the new option, and something like:
>
>      -netdev 
> socket-ng,id=socket0,mode=client,addr.type=unix,addr.path=/tmp/test.socket -net 
> nic,model=virtio,id=hostnet0
>
>    I get a connection on the socket, but the virtio-net device is not
>    connected to it (no frames received/sent).
>
>    However, if instead of "-net nic" I pass this:
>
>      -device virtio-net-pci,netdev=socket0
>
>    everything works.

I think the problem is with the hub.

When it works:

    -net socket,udp=localhost:1235,localaddr=localhost:1234 \
    -net nic,model=virtio,macaddr=9a:2b:2c:2d:2e:2f

    (qemu) info network
    hub 0
     \ hub0port1: virtio-net-pci.0: 
index=0,type=nic,model=virtio-net-pci,macaddr=9a:2b:2c:2d:2e:2f
     \ hub0port0: #net039: index=0,type=socket,socket: udp=127.0.0.1:1235

When it doesn't work (with the upcoming new syntax...):

    -net dgram,id=socket0,local.type=inet,local.host=localhost,local.port=1234,\
                          
remote.type=inet,remote.host=localhost,remote.port=1235
    -net nic,model=virtio,macaddr=9a:2b:2c:2d:2e:2f

    (qemu) info network
    hub 0
     \ hub0port0: virtio-net-pci.0: 
index=0,type=nic,model=virtio-net-pci,macaddr=9a:2b:2c:2d:2e:2f
    socket0: index=0,type=dgram,udp=127.0.0.1:1234/127.0.0.1:1235

We can see socket0 is not linked to the hub (hub0port0)

With "-device" it works because it doesn't use the hub but the netdev id:

    -device virtio-net,mac=9a:2b:2c:2d:2e:2f,netdev=socket0

    virtio-net-pci.0: 
index=0,type=nic,model=virtio-net-pci,macaddr=9a:2b:2c:2d:2e:f
     \ socket0: index=0,type=dgram,udp=127.0.0.1:1234/127.0.0.1:1235


I'm investigating...

Thanks,
Laurent