| Address: IPR CBU, FF.FFF0.0108 The backup cache tag register is a read-only register. Unless it is locked, the BC_TAG register is loaded with the results of every backup cache tag probe. When a tag or tag control parity error occurs, this register is locked against further updates. Software may read this register by using the 21164-specific I/O space address instruction. The register is unlocked whenever the EI_STAT register is read or when the user enters BC_FHIT mode. Unused tag bits in the TAG field of this register are always zero, based on the size of Bcache as determined by the BC_SIZE field in the BC_CONTROL register. | ||
| TAG<38:20> | <38:20>R | The backup cache tag field. |
| TAG_P | <17>R | Parity bit for the backup cache tag. |
| TAGCTL_V | <16>R | The tag valid bit. |
| TAGCTL_S | <15>R | The shared bit. When clear, the entry is private. |
| TAGCTL_D | <14>R | The dirty bit. |
| TAGCTL_P | <13>R | Parity bit for the tag control bits. |
| HIT | <12>R | If set, the Bcache access resulted in a hit. |