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Cannot read the structure of Hardware Feedback Interface and ThreadDirector in the memory

y4nx1ang
Beginner
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According to the Intel Manual Vol. 3A/B chatpter 15.6: the Hardware Feedback Interface and Intel® Thread Director both have a structure in memory to record some information changes of the CPU. However, I couldn’t find any information about the content of that memory region being '0'.

  1. The manual says that the memory region's address is in :

y4nx1ang_0-1693292817049.png

and the MAXPHYADDR can be found from 

y4nx1ang_1-1693292817033.png

 

     2. I have an i7-12700 CPU and the maxphyaddr is '46'. I obtained the physical address of the Hardware Feedback Interface and Thread Director structure and attempted to read it from a kernel module. However, the content of that memory region appears to be all '0'. I have ensured that both the HFI and Thread Director have been enabled.

 

Is there any method to deal with this? Thanks!

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