82598EB Datasheet, PDF (57/596 Pages) Intel Corporation – Intel® 82598EB 10 Gigabit Ethernet Controller Datasheet

Intel^® 82598EB 10 GbE Controller - PCIe
0x16
0x17
0x18
0x19
0x1A
TAG ID
0x1B
0x1C:0x1F
Tx Descriptor 6
Tx Descriptor 7
Rx Descriptor 0
Rx Descriptor 1
Rx Descriptor 2
Description
Rx Descriptor 3
Reserved
2. TAG ID Allocation for Write Transactions. Request tag allocation depends on these system
parameters:
—DCA supported/not supported in the system
—DCA enabled/disabled in the command line
—System type (chipset)
—CPU ID
The following cases provide usage examples.
Case 1 – DCA Disabled in the System:
The following table lists the write requests tags.
Tag ID
2
4
6
Write Back (WB) descriptor Tx /WB head.
WB descriptor Rx.
Write data.
Description
Case 2 – DCA Enabled in the System, but Disabled for the Request
• Fast Side Bus (FSB) platforms – If DCA is disabled for the request, the tags allocation is similar to
the case where DCA is disabled in the system.
• CSI platforms – All write requests have the tag of 0x00.
Case 3 – DCA Enabled in the System, DCA Enabled for the Request
• FSB Platforms:
—Tags are according to the lowest bits of the CPU_ID field.
—Request tag = {CPU ID [3:0], 1111b}.
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