OCC

On-Chip Controller (OCC):

OCC on POWER9

Auxillary Power ISA microprocessor on OpenPOWER CPUs. Periodically monitors chip workload, power consumption and temperature readings. Transmits temperature readings to the BMC to allow it to set appropriate fan speeds. The OCC implements any applicable power caps and supports programmable TDP limits.

OCC firmware is loaded at boot as part of the boot process and is open source.

The CME, SGPE and PGPE auxillary microprocessors handle various power management responsibilities and are managed by the OCC.

References

• OCC firmware source code (upstream)
• OCC firmware source code (Talos II variant)
• OCC development tutorial presentation - OpenPOWER Development Congress 2017 San Francisco