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66 Intel® Xeon® Processor E5-1600 v2/E5-2600 v2 Product Families
Datasheet Volume One of Two
2.5.2.9.2 Supported Responses
The typical client response is a passing FCS, a passing Completion Code and valid data.
Under some conditions, the client’s response will indicate a failure.
The PECI client response can also vary depending on the address and data. It will
respond with a passing completion code if it successfully submits the request to the
appropriate location and gets a response. Exactly what the receiving agent does with
the data or how it responds is up to that agent and is outside the scope of PECI 3.0.
2.5.2.10 WrPCIConfigLocal()
The WrPCIConfigLocal() command provides sideband write access to the PCI
configuration space that resides within the processor. PECI originators can access this
space even before BIOS enumeration of the system buses. The exact listing of
supported devices and functions for writes using this command on the processor is
defined in Table 2-19. The write accesses to registers that are locked will not take effect
but will still return a completion code of 0x40. However, write accesses to registers that
are hidden will return a completion code of 0x90.
Because a WrPCIConfigLocal() command results in an update to potentially critical
registers inside the processor, it includes an Assured Write FCS (AW FCS) byte as
part of the write data payload. In the event that the AW FCS mismatches with the
client-calculated FCS, the client will abort the write and will always respond with a bad
write FCS.
PCI Configuration addresses are constructed as shown in Figure 2-46. The write
command is subject to the same address configuration rules as defined in
Section 2.5.2.9. PCI configuration writes may be issued in byte, word or dword
granularity.
2.5.2.10.1 Command Format
The WrPCIConfigLocal() format is as follows:
Write Length: 0x07 (byte), 0x08 (word), 0x0a (dword)
Read Length: 0x01
Command: 0xe5
Table 2-13. RdPCIConfigLocal() Response Definition
Response Meaning
Bad FCS Electrical error
Abort FCS Illegal command formatting (mismatched RL/WL/Command Code)
CC: 0x40 Command passed, data is valid.
CC: 0x80 Response timeout. The processor was not able to generate the required response in a
timely fashion. Retry is appropriate.
CC: 0x81 Response timeout. The processor is not able to allocate resources for servicing this
command at this time. Retry is appropriate.
CC: 0x82 The processor hardware resources required to service this command are in a low power
state. Retry may be appropriate after modification of PECI wake mode behavior if
appropriate.
CC: 0x90 Unknown/Invalid/Illegal Request
CC: 0x91 PECI control hardware, firmware or associated logic error. The processor is unable to
process the request.