This Answer Record contains the Release Notes for the Gigabit Ethernet MAC v4.0 core.
Gigabit Ethernet MAC v4.0
ISE 6.1i with Service Pack 3 and IP Update #1 or newer
New Features in v4.0
- Added support for Spartan-3.
- Added support for ISE 6.1i software.
- Changed the Block RAM implementation of Statistics Gathering to use the transmitter clock domain when possible; this makes it less dependent upon the receiver clock, which potentially is of lower quality.
- Added a new configuration setting that allows the optional disabling of the Length/Type field length interpretation error checking in the MAC sub-layer receiver.
- HDL wrappers now contain DCM reset circuitry that drives the reset for three clock periods, according to the new DCM guidelines.
- Updated the ENMCOMMAALIGN and ENPCOMMAALIGN logic to use specific slices (rather than a range) for the logic as recommended in the RocketIO User Guide.
- Changed the VHDL top-level wrapper and demonstration testbench to lower-case signal names to avoid potential issues when case is preserved in XST.
Bug Fixes in v4.0
- Corrected an issue in which the Block RAM statistics sporadically counted up while transmitting and receiving IDLE frames, resulting in incorrect values stored in the counters (number of bad frames, frame length, etc.).
- Fixed an issue in which "Link Status" was incorrectly reported in status register 1.2 when Auto-Negotiation was disabled.
- Improved the reliability of Auto-Negotiation by correcting an issue in the Rx Elastic Buffer used in the Gigabit Ethernet MAC v3.0 core with the TBI interface.
- Removed the potential for misuse in the Gigabit Ethernet MAC v3.0 core (TBI or PHY versions) that could cause a conflict with Auto-Negotiation.
- Improved the RocketIO implementation of the Auto-Negotiation logic to handle increased clock frequency differences between the core and its link partner.
- Corrected the following counters in the Distributed Memory implementation of Statistics Gathering: Undersized frames received; Fragment frames received; Received bytes; Transmitted bytes.
- Gigabit Ethernet MAC v4.0 core cannot be generated in Linux.
This was fixed in the 6.2i software. To work around this issue, generate the core in Solaris or on a PC, and then implement your design on Linux.
- The Gigabit Ethernet MAC v4.0 core cannot be generated with a component name of "gmac_core" in COREGen; doing so causes synthesis to fail in XST.
Please refer to (Xilinx Answer 18747) for more information.
- In the Gigabit Ethernet MAC v4.0 core statistics, Undersize and Fragment statistics increment incorrectly when implemented in Block RAM.
To work around this issue, install the patch below and regenerate the core. For more information, see (Xilinx Answer 18653).
- Occasional frame loss occurs when using the Gigabit Ethernet MAC v4.0 core with the TBI interface.
To work around this issue, install the patch below and regenerate the core. For more information, see (Xilinx Answer 18792).
- Simulating the Gigabit Ethernet MAC v4.0 core with the PHY interface using the demo testbench causes X_FF Hold violations and X's on outputs.
To work around this issue, install the patch below and regenerate the core. For more information, see (Xilinx Answer 19404).
Install the patch as follows:
1. Unzip the contents of the ".zip" file or "tar.gz" archive to the root directory of the Xilinx installation. Select the option that allows the extractor to overwrite all of the existing files and maintain the directory structure pre-defined in the archive.
Determine the Xilinx installation directory by entering the following at the command prompt:
UNIX or Linux
Determine the Xilinx installation directory by typing the following:
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.