If your networking is failing after updating to the latest git version of QEMU...

[Thomas Huth]

... it might have happened due to the removal of the "slirp" submodule from 
the git repository. For example if you see an error message like this:

 Parameter 'type' expects a netdev backend type

this likely means that the "user" mode backend type is not available in your 
binary anymore. To fix it, simply install "libslirp-devel" (or libslirp-dev 
or however it is called) from your OS distribution and recompile.

See also the commit message here:
 https://gitlab.com/qemu-project/qemu/-/commit/5890258aeeba303704

 Thomas