The GigaBit Ethernet Media Access Controller (GRETH_GBIT) supports 10/100/1000 MBit speed in both full- and half-duplex operation. The dataflow is handled through DMA channels, one for transmit and one for receive. The Ethernet interface supports MII and GMII interfaces connected to an external PHY. The GRETH_GBIT also provides access to the MII Management interface which is used to configure the PHY. Some of the supported features for the DMA channels are Scatter Gather I/O and TCP/UDP over IPv4 checksum offloading for both receiver and transmitter. Software drivers are provided for VxWorks, RTEMS, eCos, uClinux and Linux 2.6.