Signed-off-by: Michael Brown <mcb30@ipxe.org>

Add the tap driver that can be used like:
$ ./ipxe.linux --net tap,if=tap0,mac=00:0c:29:c5:39:a1
The if setting is mandatory.

Signed-off-by: Piotr Jaroszyński <p.jaroszynski@gmail.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

Add the base to build linux drivers and the linux UI code on.  UI
fills device requests, which are later walked over by the linux
root_driver and delegated to specific linux drivers.

Signed-off-by: Piotr Jaroszyński <p.jaroszynski@gmail.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>