On 4/9/2019 5:56 PM, Vladimir Oltean wrote:

With the newly added DSA_TAG_PROTO_8021Q, switch devices that don't
support a native insertion/extraction header on the CPU port may still
enjoy the benefits of port isolation with a custom VLAN tag.

For this, they need to have a customizable TPID in hardware and a new
Ethertype to distinguish between real 802.1Q traffic and the private
tags used for port separation.

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>

Why was not using ETH_P_EDSA not suitable? Also how do we intend to use
this from user-space? The latest libpcap/tcpdump changes essentially
look at the dsa/tagging sysfs attribute for the master network device to
determine what type of underlying tagging protocol is used, since you
allocated a new one (NET_DSA_TAG_8021Q) you could have added a matching
string in sysfs so we can recognize it?
-- 
Florian