82598EB Datasheet, PDF (226/596 Pages) Intel Corporation – Intel® 82598EB 10 Gigabit Ethernet Controller Datasheet

Intel^® 82598EB 10 GbE Controller - Receive Functionality
• Reserved (bits 19:12) – Reserved
• DYNINT (bit 11) – Packet caused immediate interrupt via dynamic interrupt moderation
• UDPV (bit 10) – Valid UDP checksum
• Reserved (bit 9) – Reserved
• CRCV (bit 8) – Speculative CRC valid
• PIF (bit 7) – Passed inexact filter
• IPCS (bit 6) – IPv4 checksum calculated on packet
• L4CS (bit 5) – TCP checksum calculated on packet
• UDPCS (bit 4) – UDP checksum calculated on packet
• VP (bit 3) – Packet is 802.1q (matched VET). Indicates strip VLAN field.
• Reserved (bit 2) – Reserved
• EOP (bit 1) – End of packet
• DD (bit 0) – Descriptor done
DYNINT
Indicates that this packet caused an immediate interrupt via dynamic interrupt moderation.
CRCV
Hardware speculatively found a valid CRC-32. It is up to the software device driver to determine the
validity of this indication of a correct CRC-32.
PIF
Hardware supplies the PIF field to expedite software processing of packets. Software must examine any
packet with PIF set to determine whether to accept the packet. If PIF is clear, then the packet is known
to be for this station so software need not look at the packet contents. In general, packets passing only
the Multicast Vector (MTA) but not any of the MAC address exact filters (RAH, RAL) has PIF set. There
are considerations that has PIF set:
• In non-promiscuous multicast mode (MCSTCTRL.MPE = 0b) or ignore broadcast mode
(FCTRL.BAM = 0b), the PIF bit is set if a packet matches inexact filter (or imperfect – MTA) but
not matching any exact (RAH, RAL) filter.
EOP
Packets that exceed the receive buffer size span multiple receive buffers. EOP indicates whether this is
the last buffer for an incoming packet.
DD
Indicates whether hardware is finished with the descriptor. When set along with EOP, the received
packet is complete in main memory. Software can determine buffer usage by setting the status byte DD
bit to 0b before making the descriptor available to hardware, and checking it for non-zero content at a
later time. For multi-descriptor packets, packet status is provided in the final descriptor of the packet
(EOP set). If EOP is not set for a descriptor, only the Address, Length, and DD bits are valid.
VP
The VP field indicates whether the incoming packet's type matches VET and the VLAN field is stripped (if
the packet is a VLAN (802.1q) type). It's set if the packet type matches VET and VLNCTRL.VME is set.
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