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+IP OVER INFINIBAND
+ The ib_ipoib driver is an implementation of the IP over InfiniBand
+ protocol as specified by the latest Internet-Drafts issued by the
+ IETF ipoib working group. It is a "native" implementation in the
+ sense of setting the interface type to ARPHRD_INFINIBAND and the
+ hardware address length to 20 (earlier proprietary implementations
+ masqueraded to the kernel as ethernet interfaces).
+Partitions and P_Keys
+ When the IPoIB driver is loaded, it creates one interface for each
+ port using the P_Key at index 0. To create an interface with a
+ different P_Key, write the desired P_Key into the main interface's
+ /sys/class/net/<intf name>/create_child file. For example:
+ echo 0x8001 > /sys/class/net/ib0/create_child
+ This will create an interface named ib0.8001 with P_Key 0x8001. To
+ remove a subinterface, use the "delete_child" file:
+ echo 0x8001 > /sys/class/net/ib0/delete_child
+ The P_Key for any interface is given by the "pkey" file, and the
+ main interface for a subinterface is in "parent."
+ By compiling the IPoIB driver with CONFIG_INFINIBAND_IPOIB_DEBUG set
+ to 'y', tracing messages are compiled into the driver. They are
+ turned on by setting the module parameters debug_level and
+ mcast_debug_level to 1. These parameters can be controlled at
+ runtime through files in /sys/module/ib_ipoib/.
+ CONFIG_INFINIBAND_IPOIB_DEBUG also enables the "ipoib_debugfs"
+ virtual filesystem. By mounting this filesystem, for example with
+ mkdir -p /ipoib_debugfs
+ mount -t ipoib_debugfs none /ipoib_debufs
+ it is possible to get statistics about multicast groups from the
+ files /ipoib_debugfs/ib0_mcg and so on.
+ The performance impact of this option is negligible, so it
+ is safe to enable this option with debug_level set to 0 for normal
+ CONFIG_INFINIBAND_IPOIB_DEBUG_DATA enables even more debug output in
+ the data path when data_debug_level is set to 1. However, even with
+ the output disabled, enabling this configuration option will affect
+ performance, because it adds tests to the fast path.
+ IETF IP over InfiniBand (ipoib) Working Group