getting macvtap for guests up and running

[Ede Wolf]

Hello,

What would be the proper syntax to configure a guest to using a macvtap
(bridge mode) interface? For a somewhat recent version of qemu
(4.1.1)? The man page does neither mention macvtap nor ipvtap. 

So far I've only been able to find either the syntax for very old
qemu versions and the more recent examples are only for
libvirt, that I do not use and am unable to derive a qemu config from
those.

Initially I thought I've had some success using the standard tap
configuration:
 
-nic tap,ifname=tap9,script=no,downscript=no,model=virtio-net-pci

At least this way the guest detects the network interface and can ping
itself, however this works currently only for privileged guests.

Moreover, as it turned out, this works even with no interface nor
macvlan on the host being configured and /dev/tap9 not being existant at
all. Probably hence no network connection. So this does something
completely different. 

And since macvtap is not exactly the same as tap, I have my doubts that
above is the proper way of doing this. Especially, since even without
binding. 

Also tried to using a bridge configuration, since macvtap is both, a
kind of tap and a bridge, but so success either. 

But what would be the correct way of getting this up and running these
days? Runnign as root as a first step would be fine. Eventually the
guest shall run unprivileged.  

Thanks for any input or ideas on how to debug this

Ede