Intel Xeon Processor E5-1600 Datasheet page 67

Table 2-13. RdPCIConfigLocal() Response Definition (Sheet 2 of 2)
Response
CC: 0x82
CC: 0x90
CC: 0x91
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
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
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
AW FCS Support: Yes
Description: Writes the data sent to the requested register address. Write Length
dictates the desired write granularity. The command always returns a completion code
indicating pass/fail status. Refer to
Intel® Xeon® Processor E5-1600/E5-2600/E5-4600 Product Families
Datasheet Volume One
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.
Unknown/Invalid/Illegal Request
PECI control hardware, firmware or associated logic error. The processor is unable to
process the request.
Table 2-19. The write accesses to registers that are locked will not take effect
Meaning
Figure
Section 2.5.5.2 for details on completion codes.
2-46. The write
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