Support network virtualization for Macos Big Sur+

Goal

The tuntap project is not maintained any more, and the homebew version seems not work to as expected. But MacOS provides networking API for VMs called vmnet.framework which can be added as a network backend. All three modes should be supported:

-shared: allows the guest to comminicate with other guests in shared mode and also with external network (Internet) via NAT

-host: allows the guest to communicate with other guests in host mode

-bridged: bridges the guest with a physical network interface

Technical details

Additional information

The following implementation are already submitted as a patch and they seem to work well on my mbp 2019 Big Sur. The only prob is that the qemu-system command should be run as root.

https://patchwork.kernel.org/project/qemu-devel/list/?series=502533

https://patchwork.kernel.org/project/qemu-devel/patch/20210708054451.9374-1-akihiko.odaki@gmail.com/