82598EB Datasheet, PDF (62/596 Pages) Intel Corporation – Intel® 82598EB 10 Gigabit Ethernet Controller Datasheet

Intel^® 82598EB 10 GbE Controller - PCIe
3.1.1.4.2.2 Multiple Tx Data Read Requests (MULR)
The 82598 supports 16 multiple pipelined requests for transmit data. In general, requests belong to the
same packet or to consecutive packets. However, the following restrictions apply:
• All requests for a packet are issued before a request is issued for a consecutive packet.
• Read requests can be issued from any of the supported queues, as long as the above restriction is
met. Pipelined requests can belong to the same queue or to separate queues. However, as noted
above, all requests for a certain packet are issued (from the same queue) before a request is
issued for a different packet (potentially from a different queue).
• The PCIe v2.0 (2.5 GT/s) specification does not insure that completions for separate requests
return in-order. Read completions for concurrent requests are not required to return in the order
issued. The 82598 handles completions that arrive in any order. Once all completions arrive for a
given request, it can issue the next pending read data request.
• The 82598 incorporates a reorder buffer to support re-ordering of completions for all issued
requests. Each request/completion can be up to 256 bytes long. The maximum size of a read
request is defined as the minimum {256 bytes, Max_Read_Request_Size}.
• In addition to the transmit data requests, the 82598 can issue eight pipelined read requests for
Tx descriptors and four pipelined read requests for Rx descriptors. The requests for Tx data, Tx
descriptors, and Rx descriptors are independently issued.
3.1.1.5 Messages
3.1.1.5.1 Received Messages
Message packets are special packets that carry a message code. The upstream device transmits special
messages to the 82598 by using this mechanism. The transaction layer decodes the message code and
responds to the message accordingly.
Table 3-4. Supported Message (as a Receiver)
Message Code
[7:0]
Routing r2r1r0
0x14
100b
0x19
011b
0x50
100b
0x7E
010b, 011b,100b
0x7E
010b,011b,100b
0x7F
010b,011b,100b
0x7F
010b, 011b,100b
0x00
011b
Message
Later Response
PM_Active_State_NAK
PME_Turn_Off
Slot power limit support (has one Dword Data)
Vendor_defined Type 0 No data
Vendor_defined Type 0 data
Vendor_defined Type 1 No data
Vendor_defined Type 1 data
Unlock
Internal Signal Set
Internal Signal Set
Silently Drop
Unsupported Request
Unsupported Request
Silently Drop
Silently Drop
Silently Drop
62