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