See ibm,opal/power-mgt device tree entries for device tree structure describing power management facilities.
There exist a few debug knobs that can be set via nvram settings. These are not ABI and may be changed or removed at any time.
Disabling specific stop states¶
On boot, specific stop states can be disabled via setting a mask. For example, to disable all but stop 0,1,2, use ~0xE0000000.
nvram -p ibm,skiboot --update-config opal-stop-state-disable-mask=0x1FFFFFFF