default behavior by specifying the correct offset incurred by each individual
RX packet. Tail taggers do not cause issues to the flow dissector.
+Checksum offload should work with category 1 and 2 taggers when the DSA master
+driver declares NETIF_F_HW_CSUM in vlan_features and looks at csum_start and
+csum_offset. For those cases, DSA will shift the checksum start and offset by
+the tag size. If the DSA master driver still uses the legacy NETIF_F_IP_CSUM
+or NETIF_F_IPV6_CSUM in vlan_features, the offload might only work if the
+offload hardware already expects that specific tag (perhaps due to matching
+vendors). DSA slaves inherit those flags from the master port, and it is up to
+the driver to correctly fall back to software checksum when the IP header is not
+where the hardware expects. If that check is ineffective, the packets might go
+to the network without a proper checksum (the checksum field will have the
+pseudo IP header sum). For category 3, when the offload hardware does not
+already expect the switch tag in use, the checksum must be calculated before any
+tag is inserted (i.e. inside the tagger). Otherwise, the DSA master would
+include the tail tag in the (software or hardware) checksum calculation. Then,
+when the tag gets stripped by the switch during transmission, it will leave an
+incorrect IP checksum in place.
+
Due to various reasons (most common being category 1 taggers being associated
with DSA-unaware masters, mangling what the master perceives as MAC DA), the
tagging protocol may require the DSA master to operate in promiscuous mode, to