Extension to the netmap framework - Week 1

[Stefano Duo]

Hi,

during the first week i developed a kernel module which creates an
hardcoded vlan configuration.

The configuration is created after receiving a write call on the device
/dev/vale_vlan.
Instead if a read call is received, the module tries to delete the
hardcoded configuration.

For each configuration, the module creates: a non modified VALE switch for
every vlan, and a switch with a modified lookup function.
The modified lookup function acts differently depending on the receiving
port:
- if it's an access port, the frame is tagged and forwarded to the trunk
port.
- if it's the trunk port, it reads the vlan id, untags the frame, and
forwards it to the corresponding vlan switch.

Furthermore, i created a new kernel configuration and modified
sys/conf/files, so that the vale_vlan module can be compiled with the
kernel.

Project wiki:
https://wiki.freebsd.org/SummerOfCode2018Projects/ExtensionsToNetmap
SVN repository: https://svnweb.freebsd.org/socsvn/soc2018/sduo/

Stefano.