I said search the code. Sadly, we're not better than other open source software when it comes to documentation:-)
>This forum has a number of threads from 2011 and 2012. Saying there is
>incomplete support for receiving tagged frames. There is one from 2014
>sure I understand it.
>What I'd like - it it's possible - is to create a number of netifs (2
>- each generating and receiving packets tagged for specific VLAN.
No, such code indeed does not yet exist. But it shouldn't be too hard to write as a dummy netif driver.