how to get the PCID on X86

[ai006]

I am trying to retrieve the PCIDs of different processes during FS mode. According to the Intel 64 and IA-32 Architectures Software Developer’s Manual, PCIDs are described as follows:

PCID: Process-context identifiers.
If CPUID.01H:ECX.PCID [bit 17] = 1, the CR4.PCIDE flag can be set to 1, enabling process-context identifiers.

Essentially, if the CPUID instruction returns a value with bit 17 asserted, it indicates that PCIDs are supported, and the CR4.PCIDE flag can be set to enable this feature.

In the file src/arch/x86/fs_workload.cc, I attempted to enable PCIDs by setting CR4.PCIDE = 1 within the initState() function. However, when I read the PCID, it still returns zero.

I suspect the issue might be related to CPU configuration. I am currently examining the X86IntelMPProcessor in X86Board.py to determine how to properly enable PCIDs, but so far, I have not had any success.

Could someone help me with retrieving PCIDs?