intrte_gso_segment(structrte_mbuf*pkt,conststructrte_gso_ctx*ctx,structrte_mbuf**pkts_out,uint16_tnb_pkts_out)
Segmentation function, which supports processing of both single- and multi- MBUF packets.
Note that we refer to the packets that are segmented from the input packet as 'GSO segments'.
rte_gso_segment() doesn't check if the input packet has correct checksums, and doesn't update checksums
for output GSO segments. Additionally, it doesn't process IP fragment packets.
Before calling rte_gso_segment(), applications must set proper ol_flags for the packet. The GSO library
uses the same macros as that of TSO. For example, set RTE_MBUF_F_TX_TCP_SEG and RTE_MBUF_F_TX_IPV4 in
ol_flags to segment a TCP/IPv4 packet. If rte_gso_segment() succeeds, the RTE_MBUF_F_TX_TCP_SEG flag is
removed for all GSO segments and the input packet.
Each of the newly-created GSO segments is organized as a two-segment MBUF, where the first segment is a
standard MBUF, which stores a copy of packet header, and the second is an indirect MBUF which points to a
section of data in the input packet. Since each GSO segment has multiple MBUFs (i.e. typically 2 MBUFs),
the driver of the interface which the GSO segments are sent to should support transmission of multi-
segment packets.
If the input packet is GSO'd, all the indirect segments are attached to the input packet.
rte_gso_segment() will not free the input packet no matter whether it is GSO'd or not, the application
should free it after calling rte_gso_segment().
If the memory space in pkts_out or MBUF pools is insufficient, this function fails, and it returns (-1) *
errno. Otherwise, GSO succeeds, and this function returns the number of output GSO segments filled in
pkts_out.
Parameterspkt The packet mbuf to segment.
ctx GSO context object pointer.
pkts_out Pointer array used to store the MBUF addresses of output GSO segments, when
rte_gso_segment() succeeds.
nb_pkts_out The max number of items that pkts_out can keep.
Returns
• The number of GSO segments filled in pkts_out on success.
• Return 0 if it does not need to be GSO'd.
• Return -ENOMEM if run out of memory in MBUF pools.
• Return -ENOTSUP for protocols that can not be segmented.
• Return -EINVAL for invalid parameters.