82583V Datasheet, PDF (240/374 Pages) Intel Corporation – Intel® 82583V GbE Controller

82583V GbE Controller—Driver Programing Interface
Note:
PCSD: The Packet Checksum and IP Identification fields. Only one of the two options is
reported in the Rx descriptor. The RXCSUM.PCSD affect is listed as follows:
RXCSUM.PCSD
Legacy Rx Descriptor
(RCTL.DTYP = 00b)
Extended or Header Split Rx
Descriptor
(RCTL.DTYP = 01b)
0b (Checksum Enable)
1b (Checksum Disable)
Packet checksum is reported in the
Rx Descriptor
Unsupported configuration.
Packet checksum and IP
identification are reported in the Rx
Descriptor
Reserved.
PCSS IPPCSE: The PCSS and the IPPCSE control the packet checksum calculation. The
packet checksum is reported in the receive descriptor when the RXCSUM.PCSD bit is
cleared.
If RXCSUM.IPPCSE cleared (the default value), the checksum calculation that is
reported in the Rx Packet Checksum field is the unadjusted 16-bit ones complement of
the packet. The Packet Checksum starts from the byte indicated by RXCSUM.PCSS
(zero corresponds to the first byte of the packet), after VLAN stripping if enabled by the
CTRL.VME. For example, for an Ethernet II frame encapsulated as an 802.3ac VLAN
packet and with RXCSUM.PCSS set to 14, the packet checksum would include the entire
encapsulated frame, excluding the 14-byte Ethernet header (DA, SA, Type/Length) and
the 4-byte VLAN tag. The Packet Checksum does not include the Ethernet CRC if the
RCTL.SECRC bit is set. Software must make the required offsetting computation (to
back out the bytes that should not have been included and to include the pseudo-
header) prior to comparing the Packet Checksum against the TCP checksum stored in
the packet.
If RXCSUM.IPPCSE is set, the Packet Checksum is aimed to accelerate checksum
calculation of fragmented UDP packets.
The PCSS value should not exceed a pointer to IP header start or else it will erroneously
calculate IP header checksum or TCP/UDP checksum.
RXCSUM.IPOFLD is used to enable the IP Checksum offloading feature. If
RXCSUM.IPOFLD is set to one, the 82583V calculates the IP checksum and indicates a
pass/fail indication to software via the IP Checksum Error bit (IPE) in the Error field of
the receive descriptor. Similarly, if RXCSUM.TUOFLD is set to one, the 82583V
calculates the TCP or UDP checksum and indicates a pass/fail indication to software via
the TCP/UDP Checksum Error bit (TCPE). Similarly, if RFCTL.IPv6_DIS and
RFCTL.IP6Xsum_DIS are cleared to zero and RXCSUM.TUOFLD is set to one, the
82583V calculates the TCP or UDP checksum for IPv6 packets. It then indicates a pass/
fail condition in the TCP/UDP Checksum Error bit (RDESC.TCPE).
This applies to checksum offloading only. Supported frame types:
• Ethernet II
• Ethernet SNAP
RXCSUM.CRCOFL is used to enable the CRC32 checksum offloading feature. If
RXCSUM.CRCOFL is set to one, the 82583V calculates the CRC32 checksum and
indicates a pass/fail indication to software via the CRC32 Checksum Error bit (CRCE) in
the Error field of the receive descriptor.
This register should only be initialized (written) when the receiver is not enabled (for
example, only write this register when RCTL.EN = 0b).
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