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IP OVER INFINIBAND
The ib_ipoib driver is an implementation of the IP over InfiniBand
protocol as specified by RFC 4391 and 4392, 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."
Debugging Information
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 files in the debugfs
virtual filesystem. By mounting this filesystem, for example with
mount -t debugfs none /sys/kernel/debug
it is possible to get statistics about multicast groups from the
files /sys/kernel/debug/ipoib/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
operation.
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.
References
IETF IP over InfiniBand (ipoib) Working Group
http://ietf.org/html.charters/ipoib-charter.html
Transmission of IP over InfiniBand (IPoIB) (RFC 4391)
http://ietf.org/rfc/rfc4391.txt
IP over InfiniBand (IPoIB) Architecture (RFC 4392)
http://ietf.org/rfc/rfc4392.txt
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