linux/Documentation/networking/gianfar.txt
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   1The Gianfar Ethernet Driver
   2Sysfs File description
   3
   4Author: Andy Fleming <afleming@freescale.com>
   5Updated: 2005-07-28
   6
   7SYSFS
   8
   9Several of the features of the gianfar driver are controlled
  10through sysfs files.  These are:
  11
  12bd_stash:
  13To stash RX Buffer Descriptors in the L2, echo 'on' or '1' to
  14bd_stash, echo 'off' or '0' to disable
  15
  16rx_stash_len:
  17To stash the first n bytes of the packet in L2, echo the number
  18of bytes to buf_stash_len.  echo 0 to disable.
  19
  20WARNING: You could really screw these up if you set them too low or high!
  21fifo_threshold:
  22To change the number of bytes the controller needs in the
  23fifo before it starts transmission, echo the number of bytes to 
  24fifo_thresh.  Range should be 0-511.
  25
  26fifo_starve:
  27When the FIFO has less than this many bytes during a transmit, it
  28enters starve mode, and increases the priority of TX memory
  29transactions.  To change, echo the number of bytes to
  30fifo_starve.  Range should be 0-511.
  31
  32fifo_starve_off:
  33Once in starve mode, the FIFO remains there until it has this
  34many bytes.  To change, echo the number of bytes to
  35fifo_starve_off.  Range should be 0-511.
  36
  37CHECKSUM OFFLOADING
  38
  39The eTSEC controller (first included in parts from late 2005 like
  40the 8548) has the ability to perform TCP, UDP, and IP checksums
  41in hardware.  The Linux kernel only offloads the TCP and UDP
  42checksums (and always performs the pseudo header checksums), so
  43the driver only supports checksumming for TCP/IP and UDP/IP
  44packets.  Use ethtool to enable or disable this feature for RX
  45and TX.
  46
  47VLAN
  48
  49In order to use VLAN, please consult Linux documentation on
  50configuring VLANs.  The gianfar driver supports hardware insertion and
  51extraction of VLAN headers, but not filtering.  Filtering will be
  52done by the kernel.
  53
  54MULTICASTING
  55
  56The gianfar driver supports using the group hash table on the
  57TSEC (and the extended hash table on the eTSEC) for multicast
  58filtering.  On the eTSEC, the exact-match MAC registers are used
  59before the hash tables.  See Linux documentation on how to join
  60multicast groups.
  61
  62PADDING
  63
  64The gianfar driver supports padding received frames with 2 bytes
  65to align the IP header to a 16-byte boundary, when supported by
  66hardware.
  67
  68ETHTOOL
  69
  70The gianfar driver supports the use of ethtool for many
  71configuration options.  You must run ethtool only on currently
  72open interfaces.  See ethtool documentation for details.
  73
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