Intel® Core™ Ultra 200H and 200U Series Processors CFG and MEM Registers
| ID | Date | Version | Classification |
|---|---|---|---|
| 844345 | 01/29/2025 | 001 | Public |
BIOS Mailbox Interface (BIOS_Mailbox_Interface_0_0_0_MCHBAR_PCU) – Offset 5da4
Control and Status register for the BIOS-to-Firmware
| Bit Range | Default | Access | Field Name and Description |
|---|---|---|---|
| 31 | 0h | RW/1S/V | Run/Busy Bit (RUN_BUSY) SW may write to the two mailbox registers only when RUN_BUSY is cleared (0b). After setting this bit, SW will poll this bit until it is cleared. |
| 30:29 | 0h | RO | Reserved |
| 28:16 | 0h | RW/V | (PARAM2) This field contains additional parameters associated with specific commands. These are documented in the BIOS Writers Guide |
| 15:8 | 0h | RW/V | (PARAM1) This field contains additional parameters associated with specific commands. These are documented in the BIOS Writers Guide |
| 7:0 | 0h | RW/V | (COMMAND) On RUN_BUSY assertion this field should contain the SW request command, on RUN_BUSY deassrtion this field will contain the Firmware response code |