Thanks for this feedback
Looking at the IBM doc, the STOP4 and subsequent states (STOP5, STOP11) have some similarities to S3 sleep. They are not related to full hibernation/suspend.
For those states:
- are they supported in the Talos II / Blackbird firmware?
- are they supported in the Linux (or *BSD) kernels?
- do they require any special utilities in the userspace or desktop?
For a full hibernate / suspend to disk: that particular IBM doc doesn't really indicate whether hibernate is supported.
In the S3 sleep mode from the x86 world, similar to the POWER modes where some cores remain active, RAM continues to have power.
In the full hibernate, you can completely unplug the power supply. All state from the CPU, RAM, hardware and GPU has been persisted on disk and all of those devices can recover their state when power comes back.