Re: qemu-system-x86_64: warning: hub 0 with no nics

[Peter Maydell]

On Sun, 27 Oct 2019 at 14:04, <address@hidden> wrote:
> I cannot get networking to work with qemu. I have on my computer a bridge 
> br-lan with DHCP that I already use for LXC container and WIFI clients. I 
> would like to have my KVM containers join this bridge, so that they can get 
> an 192.168.1.x IP-address.
>
> From reading various blogs, I used the following command line:
>
> qemu-system-x86_64 -enable-kvm -cpu host -smp 4 -m 1G \
> -drive 
> file=/mnt/data/share/internal/debian10.qcow2,if=virtio,copy-on-read=on,if=virtio,format=qcow2
>  \
> -cdrom /mnt/data/share/internal/firmware-10.1.0-amd64-netinst.iso \
> -device virtio-net-pci,mac=E2:F2:6A:01:9D:C9,netdev=br0 -netdev 
> bridge,br=br-lan,id=br0 \
> -usb -device usb-tablet -net user,smb=$HOME -vnc 0.0.0.0:1 -k de
>
> Unfortunately I get the following error:
> qemu-system-x86_64: warning: hub 0 with no nics

This warning is telling you that you've created an emulated
network but not plugged any emulated network devices in to it --
it's a legal configuration but almost certainly not what you want.
The cause here is that you're trying to mix network configuration
methods -- there is a 'new style' with "-netdev ...,id=foo"
plus "-device ..,netdev=foo", and there is also an old style
with "-net". Either will work (though -net is deprecated and
the new style is preferred), but mixing the two as your command
line does is going to result in confusion at best. Dropping
the "-net user,smb=$HOME" will get rid of the unused network
and the warning.

thanks
-- PMM