Bill Fischofer(Bill-Fischofer-Linaro) replied on github web page:
include/odp/api/spec/packet_io.h
line 58
@@ -314,13 +330,27 @@ typedef union odp_pktin_config_opt_t {
* Packet output configuration options listed in a bit field structure. Packet
* output checksum insertion may be enabled or disabled. When it is enabled,
* implementation will calculate and insert checksum into every outgoing packet
- * by default. Application may use a packet metadata flag to disable checksum
- * insertion per packet bases. For correct operation, packet metadata must
- * provide valid offsets for the appropriate protocols. For example, UDP
- * checksum calculation needs both L3 and L4 offsets (to access IP and UDP
- * headers). When application (e.g. a switch) does not modify L3/L4 data and
- * thus checksum does not need to be updated, output checksum insertion should
- * be disabled for optimal performance.
+ * by default. Application may disable checksum insertion (e.g.
+ * odp_packet_l4_chksum_insert()) on per packet basis. For correct operation,
+ * packet metadata must provide valid offsets for the appropriate protocols.
+ * For example, UDP checksum calculation needs both L3 and L4 offsets (to
access
+ * IP and UDP headers). When application (e.g. a switch) does not modify L3/L4
+ * data and thus checksum does not need to be updated, output checksum
insertion
+ * should be disabled for optimal performance.
+ *
+ * Packet flags (odp_packet_has_*()) are ignored for the purpose of checksum
+ * insertion in packet output.
+ *
+ * UDP, TCP and SCTP checksum insertion must not be requested for IP fragments.
+ * Use checksum override function (odp_packet_l4_chksum_insert()) to disable
+ * checksumming when sending a fragment through a packet IO interface that has
+ * the relevant L4 checksum insertion enabled.
Comment:
Agreed, however whether IPsec fragments the output for a given packet may not
be known in advance by the application. As worded, this would seem to imply
that I cannot request L4 checksum processing for inline IPsec output on the off
chance it may need to be fragmented. I doubt if that is your intent here.
https://github.com/Linaro/odp/pull/167#discussion_r137662661
updated_at 2017-09-07 21:41:40
