Datasheet
15
Specification Clarifications—Intel
®
82599 10 GbE Controller
2.1 Specification Clarifications
1 SFP+ Statement
It is important to note that the SFP+ Specification (SFF-8431) is a system level specification and
performance varies as a function of a board design and connector vendor. When designing a system to
meet this specification, it is important to take these system level functions into account.
The performance measured for the 82599 was captured in a board design as described in the Design
Considerations section of the Intel
®
82599 10 Gigabit Ethernet Controller Datasheet. Reference this
material for detail.
2 PCIe Completion Timeout Value Must Be Properly
Set
The 82599 Completion Timeout Value[3:0] must be properly set by the system BIOS in the PCIe
Configuration Space Device Control 2 register (0xC8; W). Failure to do so can cause unexpected
completion timeouts.
The 82599 complies with the PCIe 2.0 specification for the completion timeout mechanism and
programmable timeout values. The PCIe 2.0 specification provides programmable timeout ranges
between 50s to 64s with a default time range of 50s - 50ms. The 82599 defaults to a range of
16 ms – 32 ms.
The completion timeout value must be programmed correctly in PCIe configuration space (in Device
Control 2 register); the value must be set above the expected maximum latency for completions. This
ensures that the 82599 receives completions for the requests it sends out. Failure to properly set the
completion timeout value can result in the device timing out prior to a completion returning.
The 82599 can be programmed to resend a completion request after a completion timeout (the original
completion is assumed lost). But if the original completion arrives after a resend request, two
completions may arrive for the same request; this can cause unpredictable behavior. Intel EEPROM
images set the resend feature to off. Intel recommends that you do not change this setting.
For details on completion timeout operation, refer to the Datasheet.
3 NC-SI Set Link Command Support
The NC-SI Set Link command is used to configure the LAN interface with specific provided settings. The
settings include link speed, duplex, pause capability, and other vendor specified settings.
The command fields have enough flexibility to configure a 10/100/1000 Mb/s LAN port, but the support
for 10 GbE is not fully defined in the NC-SI specification. Different 10 GbE options as defined by LMS,
10G_PMA_PMD_PARALLEL and KR_support fields of the AUTOC register cannot be defined by the NC-SI
Set Link command. Due to this limitation, the 82599 LAN ports cannot be configured by the NC-SI Set
Link command.