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[linux-2.6.git] / Documentation / networking / gianfar.txt

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+The Gianfar Ethernet Driver
+Sysfs File description
+
+Author: Andy Fleming <afleming@freescale.com>
+Updated: 2005-07-28
+
+SYSFS
+
+Several of the features of the gianfar driver are controlled
+through sysfs files.  These are:
+
+bd_stash:
+To stash RX Buffer Descriptors in the L2, echo 'on' or '1' to
+bd_stash, echo 'off' or '0' to disable
+
+rx_stash_len:
+To stash the first n bytes of the packet in L2, echo the number
+of bytes to buf_stash_len.  echo 0 to disable.
+
+WARNING: You could really screw these up if you set them too low or high!
+fifo_threshold:
+To change the number of bytes the controller needs in the
+fifo before it starts transmission, echo the number of bytes to 
+fifo_thresh.  Range should be 0-511.
+
+fifo_starve:
+When the FIFO has less than this many bytes during a transmit, it
+enters starve mode, and increases the priority of TX memory
+transactions.  To change, echo the number of bytes to
+fifo_starve.  Range should be 0-511.
+
+fifo_starve_off:
+Once in starve mode, the FIFO remains there until it has this
+many bytes.  To change, echo the number of bytes to
+fifo_starve_off.  Range should be 0-511.
+
+CHECKSUM OFFLOADING
+
+The eTSEC controller (first included in parts from late 2005 like
+the 8548) has the ability to perform TCP, UDP, and IP checksums
+in hardware.  The Linux kernel only offloads the TCP and UDP
+checksums (and always performs the pseudo header checksums), so
+the driver only supports checksumming for TCP/IP and UDP/IP
+packets.  Use ethtool to enable or disable this feature for RX
+and TX.
+
+VLAN
+
+In order to use VLAN, please consult Linux documentation on
+configuring VLANs.  The gianfar driver supports hardware insertion and
+extraction of VLAN headers, but not filtering.  Filtering will be
+done by the kernel.
+
+MULTICASTING
+
+The gianfar driver supports using the group hash table on the
+TSEC (and the extended hash table on the eTSEC) for multicast
+filtering.  On the eTSEC, the exact-match MAC registers are used
+before the hash tables.  See Linux documentation on how to join
+multicast groups.
+
+PADDING
+
+The gianfar driver supports padding received frames with 2 bytes
+to align the IP header to a 16-byte boundary, when supported by
+hardware.
+
+ETHTOOL
+
+The gianfar driver supports the use of ethtool for many
+configuration options.  You must run ethtool only on currently
+open interfaces.  See ethtool documentation for details.