General Description: The Rx Elastic Buffer in the 1000BASE-X PCS v3.0 core with the TBI interface has a weakness that results in unreliable operation of Auto-Negotiation. This problem is caused by differences in clock frequencies between the core and the device to which it is connected. This does not affect the 1000BASE-X PCS/PMA core that uses Rocket I/O for the PHY.
The Rx Elastic Buffer has been fixed to prevent such a problem. To obtain this fix, apply the patch found in the Release Notes for the 1000BASE-X PCS/PMA v3.0 core in (Xilinx Answer 17335).