Performance counters on Ampere eMAG

From: John F Carr <jfc_at_mit.edu>
Date: Fri, 07 Feb 2025 20:33:58 UTC 
Is anybody successfully using performance counters on ARM eMAG?  I am getting bad counts from pmcstat -p.
Example:

# pmcstat -p cpu_cycles -p wait_cycles -p exc_svc echo \\c
# p/cpu_cycles p/wait_cycles  p/exc_svc
      4298795386             0         47  
# pmcstat -p cpu_cycles -p wait_cycles -p exc_svc echo \\c
# p/cpu_cycles p/wait_cycles  p/exc_svc
         3806520    4294967296 4294967343 

The large numbers may be 0x100000000 (2^32) greater than the correct numbers.

I am running 14.2-STABLE.    Cortex A57 and A72 running CURRENT work fine.

John Carr