Fixed in Oracle Solaris SRU 25 (Hardware Management Pack for Oracle Solaris version 220.127.116.11).
On SPARC T8 systems running Oracle Solaris 11.3 SRU 23 or SRU 24, the fwupdate command is unable to perform automated host power cycles required after some firmware updates. This can happen even if the firmware metadata supports an automated power cycle. If your system is affected by this issue, you might see a message similar to the following during an update:
System Power Cycle required for some applied firmware Do you wish to automatically initiate system power cycle now? [y/n]? y IPMI TLS Authentication Failed: 0xf WARNING: File transfer to SP will go through the KCS interface. This may take a long time ( > 60 min). A PowerCycle was attempted and is not currently supported on this platform. You will need to perform a manual power cycle. Please reference your firmware documentation for more information. Automatic system power action failed. Terminating fwupdate. Please reset system manually and then proceed.
If you encounter this issue, you need to power cycle the host manually in order to complete the update process. To view the new firmware version after the host has been power cycled, run the fwupdate list command on the updated device.