Intel® Core™ Ultra Series 3 Processors I/O Registers
| ID | Date | Version | Classification |
|---|---|---|---|
| 872352 | 04/14/2026 | 001 | Public |
Power Control (HfPWRCTL) – Offset 1d18
This register controls the power domain operations, under host SW management.
| Bit Range | Default | Access | Field Name and Description |
|---|---|---|---|
| 15 | 0h | RW | Prevent HUB-ULP Power Gating (PHUBULPPG) FW write this bit to 1 to prevent the domain from entering power gating state. When cleared to 0, it indicates it no longer needs to keep the domain alive and allow power gating to take place after it is idle (if power gating is enabled). |
| 14:13 | 0h | RO | Reserved (Preserved) (RSVD14) SW must preserve the original value when writing. |
| 12 | 0h | RW | Wake / Prevent ML Power Gating (WPMLPG) SW write this bit to 1 to prevent the domain from entering power gating state, or to wake up if it is already power gated. When cleared to 0, it indicates it no longer needs to keep the domain alive and allow power gating to take place after it is idle (if power gating is enabled). |
| 11:10 | 0h | RO | Reserved (Preserved) (RSVD11) SW must preserve the original value when writing. |
| 9:8 | 0h | RW | Wake / Prevent IOx Power Gating (WPIOxPG) SW write this bit to 1 to prevent the domain from entering power gating state, or to wake up if it is already power gated. When cleared to 0, it indicates it no longer needs to keep the domain alive and allow power gating to take place after it is idle (if power gating is enabled). |
| 7 | 0h | RO | Reserved |
| 6 | 0h | RW | Prevent HUB-HP Power Gating (PHUBHPPG) FW write this bit to 1 to prevent the domain from entering power gating state. When cleared to 0, it indicates it no longer needs to keep the domain alive and allow power gating to take place after it is idle (if power gating is enabled). |
| 5 | 0h | RW | Prevent HST Power Gating (PHSTPG) FW write this bit to 1 to prevent the domain from entering power gating state. When cleared to 0, it indicates it no longer needs to keep the domain alive and allow power gating to take place after it is idle (if power gating is enabled). |
| 4:0 | 0h | RO | Reserved (Preserved) (RSVD4) SW must preserve the original value when writing. |