| Field Name | Bits | Type | Reset Value | Description |
|---|
| Reserved | 63 | razRead as zero | 0x0 | reserved |
| pos_early_wr_comp_en | 62 | rwNormal read/write | 0x1 | Enables early write acknowledgment in Address Region 0; used to improve write performance |
| pos_early_rdack_en | 61 | rwNormal read/write | 0x1 | Enables sending early read receipts from HN-I in Address Region 0; used to improve ordered read performance |
| ser_devne_wr | 60 | rwNormal read/write | 0x0 | Used to serialize Device-nGnRnE writes within Address Region 0 |
| ser_all_wr | 59 | rwNormal read/write | 0x0 | Used to serialize all writes within Address Region 0 |
| physical_mem_en | 58 | rwNormal read/write | 0x0 | Address Region 0 follows Arm Architecture Reference Manual physical memory ordering guarantees |
| Reserved | 57:6 | razRead as zero | 0x0 | reserved |
| order_region_size | 5:0 | rwNormal read/write | 0x3F | <n>; used to calculate Order Region 0 size within Address Region 0 (2^n*4KB) |