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82575EB Gigabit Ethernet Controller — Content
Intel
®
82575EB Gigabit Ethernet Controller 324632-003
Software Developer’s Manual and EEPROM Guide Revision: 2.1
8 January 2011
5.5 Header Splitting and Replication ................................................................................................ 127
5.5.1 Receive Packet Checksum Offloading ................................................................................... 130
5.5.1.1 MAC Address Filter .......................................................................................................131
5.5.1.2 SNAP/VLAN Filter .........................................................................................................131
5.5.1.3 IPv4 Filter ...................................................................................................................131
5.5.1.4 IPv6 Filter ...................................................................................................................131
5.5.1.5 IPv6 Extension Headers ................................................................................................132
5.5.1.6 UDP/TCP Filter.............................................................................................................133
5.6 Packet Transmission ................................................................................................................ 133
5.6.1 Transmit Data Storage ....................................................................................................... 134
5.6.2 Transmit Contexts ............................................................................................................. 134
5.6.3 Transmit Descriptors.......................................................................................................... 135
5.6.4 Legacy Transmit Descriptor Format...................................................................................... 135
5.6.5 Transmit Descriptor Write Back Format ................................................................................ 136
5.6.5.1 Length........................................................................................................................136
5.6.5.2 Checksum Offset and Start (CSO and CSS)......................................................................136
5.6.5.3 Command Byte (CMD) ..................................................................................................137
5.6.5.4 Transmit Descriptor Status Field Format..........................................................................139
5.6.6 Transmit Descriptor Special Field Format .............................................................................. 139
5.6.7 Advanced Transmit Context Descriptor ................................................................................. 140
5.6.7.1 Maximum Segment Size (MSS) Control ...........................................................................141
5.6.8 Advanced Transmit Data Descriptor ..................................................................................... 142
5.6.8.1 Address ......................................................................................................................142
5.6.8.2 DTALEN ......................................................................................................................142
5.6.8.3 DTYP..........................................................................................................................142
5.6.8.4 DCMD.........................................................................................................................143
5.6.8.5 STA............................................................................................................................144
5.6.8.6 IDX ............................................................................................................................144
5.6.8.7 POPTS ........................................................................................................................144
5.6.8.8 PAYLEN.......................................................................................................................144
5.7 Transmit Descriptor Ring Structure ............................................................................................ 144
5.7.1 Transmit Descriptor Fetching .............................................................................................. 146
5.7.2 Transmit Descriptor Write-Back........................................................................................... 146
5.8 TCP Segmentation ................................................................................................................... 147
5.8.1 Assumptions..................................................................................................................... 148
5.8.2 Transmission Process......................................................................................................... 148
5.8.2.1 TCP Segmentation Data Fetch Control.............................................................................148
5.8.3 TCP Segmentation Performance .......................................................................................... 148
5.8.4 Packet Format .................................................................................................................. 149
5.8.5 TCP Segmentation Indication .............................................................................................. 149
5.8.6 IP and TCP/UDP Headers .................................................................................................... 151
5.8.7 IP/TCP/UDP Header Updating.............................................................................................. 156
5.8.7.1 TCP/IP/UDP Header for the First Frame ...........................................................................157
5.8.7.2 TCP/IP/UDP Header for the Subsequent Frames ...............................................................157
5.8.7.3 TCP/IP/UDP Header for the Last Frame ...........................................................................158
5.9 IP/TCP/UDP Transmit Checksum Offloading................................................................................. 158
5.10 IP/TCP/UDP Transmit Checksum Offloading in Non-Segmentation Mode .......................................... 159
5.10.1 IP Checksum .................................................................................................................... 159
5.10.2 TCP Checksum.................................................................................................................. 160
5.11 Multiple Transmit Queues ......................................................................................................... 160
5.12 Tx Completions Head Write-Back ............................................................................................... 161
5.13 Interrupts............................................................................................................................... 162
5.13.1 Interrupt Cause Register (ICR)............................................................................................ 162
5.13.2 Interrupt Cause Set Register (ICS) ...................................................................................... 163
5.13.3 Interrupt Mask Set/Read Register (IMS) ............................................................................... 163
5.13.4 Interrupt Mask Clear Register (IMC)..................................................................................... 163
5.13.5 Interrupt Acknowledge Auto-mask register (IAM)................................................................... 163
5.13.6 Extended Interrupt Cause Registers (EICR)........................................................................... 163
5.13.7 Extended Interrupt Cause Set Register (EICS)....................................................................... 164