PECI Interface
86 Thermal/Mechanical Specifications and Design Guide
7.1.4.12 WrPCIConfigLocal()
The WrPCIConfigLocal() command provides sideband write access to the PCI
configuration space that resides within the processor. PECI originators may conduct a
device/function/register enumeration sweep of this space by issuing reads in the same
manner that BIOS would. 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 7 - 20 .
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 7-41. The write
command is subject to the same address configuration rules as defined in
Section 7.1.4.11. PCI configuration writes may be issued in byte, word or dword
granularity.
7.1.4.12.1 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 7.1.7.2 for details on completion codes.
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 Request
CC: 0x91
PECI control hardware, firmware or associated logic error. The processor is unable to
process the request.
Table 7-14. RdPCIConfigLocal() Response Definition (Sheet 2 of 2)
Response Meaning
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