BOHC (SATA_AHCI_HBA) Register Description
| Register Name | BOHC |
|---|---|
| Offset Address | 0x0000000028 |
| Absolute Address | 0x00FD0C0028 (SATA_AHCI_HBA) |
| Width | 32 |
| Type | mixedMixed types. See bit-field details. |
| Reset Value | 0x00000000 |
| Description | BIOS/OS Handoff Control and Status |
Controls various global actions of the HBA.
BOHC (SATA_AHCI_HBA) Register Bit-Field Summary
| Field Name | Bits | Type | Reset Value | Description |
|---|---|---|---|---|
| Reserved | 31:5 | roRead-only | 0x0 | Reserved |
| BB | 4 | rwNormal read/write | 0x0 | BIOS Busy (BB): This bit is used by the BIOS to indicate that it is busy cleaning up for ownership change. |
| OOC | 3 | wtcReadable, write a 1 to clear | 0x0 | OS Ownership Change (OOC): This bit is set to 1 when the OOS bit transitions from 0 to 1. This bit is cleared by writing a 1 to it. Writing 0 has no effect on it. |
| SOOE | 2 | rwNormal read/write | 0x0 | SMI on OS Ownership Change Enable (SOOE): This bit, when set to 1, enables an SMI when the OOC bit has been set to 1. |
| OOS | 1 | rwNormal read/write | 0x0 | OS Owned Semaphore (OOS): The system software sets this bit to request ownership of the HBA controller. Ownership is obtained when this bit reads 1 and the BOS bit reads 0. This bit is not affected by an HBA reset. |
| BOS | 0 | rwNormal read/write | 0x0 | BIOS Owned Semaphore (BOS): The BIOS sets this bit to establish ownership of the HBA controller. BIOS will clear this bit in response to a request for ownership of the HBA by system software via OOS. This bit is not affected by an HBA reset. |