82598EB Datasheet, PDF (437/596 Pages) Intel Corporation – Intel® 82598EB 10 Gigabit Ethernet Controller Datasheet

Intel^® 82598EB 10 GbE Controller - 1 MHz SMBus Support
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Target Address
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BMC Slave Address
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Receive TCO Command
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Figure 5-9. Direct Receive Transaction Format
5.3.6 1 MHz SMBus Support
SMBus specification defines the maximum frequency of the SMBus as 100 KHz. The SMBus can be
activated up to frequency of 1 MHz. When operating at 1 MHz, few of the SMBus specification
parameters are violated. The regular SMBus can be activated in two modes: slow, which meets the
SMBus specification requirements (can be activated up to 400 KHz without violating hold and setup
time) and fast, which can be operated up to 1 MHz, but does not meet the SMBus specification.
This configuration is only available via an EEPROM setting.
The EEPROM Pass-Through SMBus Connection field defines the SMBus mode (slow SMBus/fast SMBus).
The slow SMBus DC parameters are defined in the SMBus 2.0 specification.
5.3.7 Receive TCO Flow
The 82598EB is used as a channel for receiving packets from the network link and passing them to the
external BMC. The BMC configures the 82598EB to pass these specific packets to the BMC. Once a full
packet is received from the link and identified as a manageability packet that should be transferred to
the BMC, 82598EB starts the receive TCO flow to the BMC.
82598EB uses the SMBus notification method to notify the BMC that it has data to deliver. Since the
packet size might be larger than the maximum SMBus fragment size, the packet is divided into
fragments, where the 82598EB uses the maximum fragment size allowed in each fragment (configured
via the EEPROM). The last fragment of the packet transfer is always the status of the packet. As a
result, the packet is transferred in at least two fragments. The data of the packet is transferred as part
of the receive TCO LAN packet transaction.
When SMBus alert is selected as the BMC notification method, 82598EB notifies the BMC on each
fragment of a multi fragment packet. When asynchronous notify is selected as the BMC notification
method, 82598EB notifies the BMC only on the first fragment of a received packet. It is the BMC's
responsibility to read the full packet including all the fragments.
Any timeout on the SMBus notification results in discarding the entire packet. Any NACK by the BMC
causes the fragment to be re-transmitted to the BMC on the next Receive Packet command.
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