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Intel® Xeon® Processor E5-1600/E5-2600/E5-4600 Product Families 67
Datasheet Volume One
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
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 Section 2.5.5.2 for details on completion codes.
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.
Table 2-13. RdPCIConfigLocal() Response Definition (Sheet 2 of 2)
Response Meaning