Re: [PATCH v2 net-next 07/22] ether: Add dedicated Ethertype for pseudo-802.1Q DSA tagging

[Florian Fainelli]

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@xxxxxxxxx>

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