Difficulties migrating -net command line options from QEMU 2.X to 5.X

[Paul R. Potts]

Hello all,

I have been looking through docs, Stack Overflow, Superuser, and the mailbox 
archives, but not having much luck.

I am trying to migrate a project to use QEMU 5. The older command-line options 
in question looked like this:

-net nic,vlan=0
-net socket,udp=127.0.0.1:8123,localaddr=0.0.0.0:8124,vlan=0
-net nic,vlan=1
-net socket,udp=127.0.0.1:8124,localaddr=0.0.0.0:8123,vlan=1

If I understand it correctly, and I’d love clarifications if I’m wrong, this 
creates two network busses, where the front-ends from the VM's perspective are 
two NICs that refer to the back-ends, so that code running in the VM can talk 
back and forth between client and server tasks.

I read about how the “vlan” option was deprecated, and looked at examples of 
how to replicate this same behavior. I tried to use the “hubport” option in 
various combinations but had no success. I tried to use the new -nic option 
which supposedly will create the front-end and back-end in one step, but also 
had no success. So here are the options I’m using now on QEMU 5.X to try to 
replicate the original behavior:

-net nic,id=socket0
-netdev socket,id=socket0,udp=127.0.0.1:8123,localaddr=0.0.0.0:8124
-net nic,id=socket1
-netdev socket,id=socket1,udp=127.0.0.1:8124,localaddr=0.0.0.0:8123

This gives me a bunch of warnings:

"hub port hub0port1 has no peer"
"hub port hub0port0 has no peer”
"netdev socket0 has no peer”
"netdev socket1 has no peer”
"requested NIC (socket0, model unspecified) was not created (not supported by 
this machine?)”
"requested NIC (socket1, model unspecified) was not created (not supported by 
this machine?)”

Suggestions or any similar working examples appreciated.

Paul R. Potts