| Bits | Description |
|---|---|
| 31:4 | Reserved |
| 3:2 | Loopback (defaults to 00) 00: Normal Operation 10: Near-end physical medium attachment (PMA) Loopback 01,11: Reserved |
| 1 | Reset the Ethernet receive block. Although this bit is writable, it is always read as 0 as the reset is immediate. |
| 0 | Reset the Ethernet transmit block. Although this bit is writable, it is always read as 0 as the reset is immediate. |