POWER9 Changes to OPAL API

This document is a summary of POWER9 changes to the OPAL API over what it was for POWER7 and POWER8. As the POWER series of processors (at least up to POWER9) require changes in the hypervisor to work on a new processor generation, this gives us an opportunity with POWER9 to clean up several parts of the OPAL API.

Eventually, when the kernel drops support for POWER8 and before, we can then remove the associated kernel code too.

OPAL_REINIT_CPUS

Can now be extended beyond HILE BE/LE bits. If invalid flags are set on POWER9, OPAL_UNSUPPORTED will be returned.

Device Tree

  • /ibm,opal/ compatible property now just lists ibm,opal-v3 and no longer ibm,opal-v2 (power9 and above only)
  • Use only stdout-path property from POWER9 and above as usage of linux,stdout-path is deprecated
  • Rename fsp-ipl-side as sp-ipl-side in /ipl-params
  • Add interrupt-parent property for /ibm,opal/ipmi node on POWER9 and above to make use of OPAL irqchip rather than event interface in linux.

TODO

Things we still have to do for POWER9:

  • PCI to use async API rather than returning delays

  • deprecate/remove v1 APIs where there’s a V2

  • Fix this FWTS warning:

    FAILED [MEDIUM] DeviceTreeBaseDTCWarnings: Test 3, dtc reports warnings from
    device tree: Warning (reg_format): "reg" property in /ibm,opal/flash@0 has
    invalid length (8 bytes) (#address-cells == 0, #size-cells == 0)
    
  • Remove mi-version / ml-version from /ibm,opal/firmware and replace with something better and more portable