* Generic Segmentation Offload - GSO
* Generic Receive Offload - GRO
* Partial Generic Segmentation Offload - GSO_PARTIAL
+ * SCTP accelleration with GSO - GSO_BY_FRAGS
TCP Segmentation Offload
========================
fragmentation offload are the same as TSO. However the IPv4 ID for
fragments should not increment as a single IPv4 datagram is fragmented.
+UFO is deprecated: modern kernels will no longer generate UFO skbs, but can
+still receive them from tuntap and similar devices. Offload of UDP-based
+tunnel protocols is still supported.
+
IPIP, SIT, GRE, UDP Tunnel, and Remote Checksum Offloads
========================================================
fact that the outer header also requests to have a non-zero checksum
included in the outer header.
-Finally there is SKB_GSO_REMCSUM which indicates that a given tunnel header
-has requested a remote checksum offload. In this case the inner headers
-will be left with a partial checksum and only the outer header checksum
-will be computed.
+Finally there is SKB_GSO_TUNNEL_REMCSUM which indicates that a given tunnel
+header has requested a remote checksum offload. In this case the inner
+headers will be left with a partial checksum and only the outer header
+checksum will be computed.
Generic Segmentation Offload
============================
is the outer IPv4 ID field. It is up to the device drivers to guarantee
that the IPv4 ID field is incremented in the case that a given header does
not have the DF bit set.
+
+SCTP accelleration with GSO
+===========================
+
+SCTP - despite the lack of hardware support - can still take advantage of
+GSO to pass one large packet through the network stack, rather than
+multiple small packets.
+
+This requires a different approach to other offloads, as SCTP packets
+cannot be just segmented to (P)MTU. Rather, the chunks must be contained in
+IP segments, padding respected. So unlike regular GSO, SCTP can't just
+generate a big skb, set gso_size to the fragmentation point and deliver it
+to IP layer.
+
+Instead, the SCTP protocol layer builds an skb with the segments correctly
+padded and stored as chained skbs, and skb_segment() splits based on those.
+To signal this, gso_size is set to the special value GSO_BY_FRAGS.
+
+Therefore, any code in the core networking stack must be aware of the
+possibility that gso_size will be GSO_BY_FRAGS and handle that case
+appropriately. (For size checks, the skb_gso_validate_*_len family of
+helpers do this automatically.)
+
+This also affects drivers with the NETIF_F_FRAGLIST & NETIF_F_GSO_SCTP bits
+set. Note also that NETIF_F_GSO_SCTP is included in NETIF_F_GSO_SOFTWARE.