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Advanced Receive Descriptors — Intel
®
82575EB Gigabit Ethernet Controller
324632-003 Intel
®
82575EB Gigabit Ethernet Controller
Revision: 2.1 Software Developer’s Manual and EEPROM Guide
January 2011 111
5.3.4.3 Packet Type
5.3.4.4 RSS Type
The 82575 must identify the packet type and then choose the appropriate RSS Hash Function to be
used on the packet. The RSS Type reports the packet type that was used for the RSS Hash Function.
5.3.4.5 Split Header
• SPH (bit 10) - When set to 1b, indicates that HDR_BUF_LEN field reflects the length of the header
found by the hardware.
• HDR_BUF_LEN (bit 9:0) - The length (Bytes) of the header as parsed by the 82575. In Header Split
Always mode (SPH set to 1b), this field also reflects the size of the Header that was actually stored
in the buffer. In split mode when HBO is set the HDR_BUF_LEN can be greater then 0 though
nothing is written to the header buffer. In Header Replication mode (SPH is set in this mode, too)
however, this does not reflect the size of the data actually stored in the header buffer, because the
82575 fills the buffer up to the size configured by SRRCTL[n].BSIZEHEADER which might be larger
than the header size reported here.
Packet Types Supported by Packet Split
The 82575 provides header split for the packet types listed in Table 31. Other packet types are posted
sequentially in the host packet buffer. Each line in Table 31 has an enable bit in the PSRTYPE register.
When one of the bits is set, the corresponding packet type is split.
Field Description
Reserved (bits 11:8) Reserved
NFS (bit 7) NFS header present
SCTP (bit 6) SCTP header present
UDP (bit 5) UDP header present
TCP (bit 4) TCP header present
IPv6E (bit 3) IPv6 header includes extensions
IPv6 (bit 2) IPv6 header present
IPv4E (bit 1) IPv4 header includes extensions
IPv4 (bit 0) IPv4 header present
Packet Type Description
0h No hash computation done for this packet.
1h HASH_TCP_IPV4
2h HASH_IPV4
3h HASH_TCP_IPV6
4h HASH_IPV6_EX
5h HASH_IPV6
6h HASH_TCP_IPV6_EX
7h HASH_UDP_IPV4
8h HASH_UDP_IPV6
9h HASH_UDP_IPV6_EX
Ah - Fh Reserved