General Description: This Answer Record contains the Gigabit Ethernet MAC - F_IP3 Release Notes.
Gigabit Ethernet MAC (GMAC)
New Features in v3.0 - New PCS configuration with a TBI interface. - Core is customizable through the 5.2i CORE Generator GUI. - Support for new top-level HDL wrappers (VHDL and Verilog) containing the clock management logic and all I/Os for the core. You can manually customize this wrapper if needed. - New option for generating the core without the Host Management Interface and substituting a configuration vector in its place.
Bug Fixes in v3.0 - Improved reliability for a potential metastability condition involving the handling of ENPCOMMAALIGN/ENMCOMMAALIGN (1000BASE-X PCS/PMA configuration). - Corrected an issue regarding the "Flying MSB" value of the "Frames Received OK" statistic counter at address 0x000. - Received frames with Type fields are now correctly checked against the minimum frame length. - Fixed a problem regarding the independent resets for the TX, RX, and Flow Control logic. - Receiver can now process Reserved GMII encodings (see IEEE802.3 specification Table 35-2) that occur at any time.
Known Issues If the Gigabit Ethernet MAC v3.0 core is configured to implement statistics in Block RAM, there is the potential for a problem in which the statistics counters may sporadically count up while transmitting and receiving IDLE frames. As a result, the values stored in the counters (number of bad frames, frame length, etc.) might be incorrect. - To work around this, please install the patch below and regenerate the core. For more information, please refer to (Xilinx Answer 17976).
With Auto-Negotiation disabled, the core never reports that it has lost receiver synchronization, even when the optical fiber is unplugged from the input of the design. Specifically, "Link Status" is incorrectly reported in status register 1.2 with Auto-Negotiation disabled. - To work around this, please install the patch below and regenerate the core. For more information, please refer to (Xilinx Answer 17434).
A weakness was found in the Rx Elastic Buffer used in the Gigabit Ethernet MAC v3.0 core with the TBI interface which resulted in unreliable operation of Auto-Negotiation. - To work around this, please install the patch below and regenerate the core. For more information, please refer to (Xilinx Answer 17614).
There is a potential for misuse in the Gigabit Ethernet MAC v3.0 core, TBI or PHY versions, that could cause a conflict with Auto-Negotiation. The symptoms are such that when the fiber optic cable is pulled out of the receiver, the transmitter continues to transmit data even though it should shut down after 10-20 ms. - To work around this, please install the patch below and regenerate the core. Alternatively, this problem can also be avoided by simply ensuring that bit 0.9 (Auto-Negotiation Restart) is always written to 0 whenever bit 0.12 is set to 0 (Auto-Negotiation = Disabled). For more information, please refer to (Xilinx Answer 17629).
For certain CORE Generator modules, user-specified component names exceeding ten characters in length might cause CORE Generator to hang. - To work around this issue, limit user-specified component names for CORE Generator cores to ten or fewer characters. In addition, limit the path to the project to 12 characters. For more information, please see (Xilinx Answer 17164).
To install the patch, perform the following: 1. Unzip the contents of the ".zip" file or "tar.gz" archive to the root directory of the Xilinx installation. Select the option to allow the extractor to overwrite all the existing files and maintain the directory structure pre-defined in the archive.
PC You can determine the Xilinx installation directory by typing the following at the command prompt: "echo %XILINX%"
UNIX You can determine the Xilinx installation directory by typing the following: "echo $XILINX"
NOTE: You might need to have system administrator privileges to install the patch.
2. After installing the patch, regenerate the Gigabit Ethernet MAC core from the CORE Generator. The core produced will contain the fix.