Intel® Core™ Ultra Series 3 Processors I/O Registers
| ID | Date | Version | Classification |
|---|---|---|---|
| 872352 | 04/14/2026 | 001 | Public |
Event Ring Dequeue Pointer Low (ERDP_LO0) – Offset 2038
The register listed in this section is at offset 203Ch for ERDP_HI0.
There are a total of 8 ERDP_LO registers available at the following address offsets:
ERDP_HI0: at offset 203Ch
ERDP_HI1: at offset 205Ch
ERDP_HI2: at offset 207Ch
ERDP_HI3: at offset 209Ch
ERDP_HI4: at offset 20BCh
ERDP_HI5: at offset 20DCh
ERDP_HI6: at offset 20FCh
ERDP_HI7: at offset 211Ch
| Bit Range | Default | Access | Field Name and Description |
|---|---|---|---|
| 31:4 | 0h | RW | Event Ring Dequeue Pointer (ERDP) This field may be used by the xHC to accelerate checking the Event Ring full condition. This field is written with the low order 3 bits of the offset of the ERST entry which defines the Event Ring segment that Event Ring Dequeue Pointer resides in. |
| 3 | 0h | RW/1C | Event Handler Busy (EHB) This flag shall be set to ‘1’ when the IP bit is set to ‘1’ and cleared to ‘0’ by software when the Dequeue Pointer register is written. |
| 2:0 | 0h | RW | Dequeue ERST Segment Index (DESI) This field may be used by the xHC to accelerate checking the Event Ring full condition. This field is written with the low order 3 bits of the offset of the ERST entry which defines the Event Ring segment that Event Ring Dequeue Pointer resides in. |